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From: n2ihn@ka2qhd.UUCP (Ed Thomas Long Branch NJ) Newsgroups: rec.ham-radio Subject: Allmods for Allmost Everything, Part II VERY long! Keywords: Clear a space on the floor, start your printer, and go for coffee. Message-ID: <371@ka2qhd.UUCP> Date: 23 Nov 90 06:15:24 GMT Distribution: na Organization: KA2QHD - OCEAN NJ Lines: 2439 These are mods I've been saving off the system for a while. People keep asking for some of the same mods. Here are all of the mods and text that have been published, giving sources credit where I was able. If any of these mods are helpful to you, please send me any mods that you may have and don't see here. I am in need of the mod to use the CTCSS decode function on both bands of the TM-721A. If you have info on this, please let me know. Thanks to everyone that helped me with this. Ed Thomas, N2IHN. P.O. Box 3233, Long Branch, NJ. 07740 >>>>>>>>>>>>>>>>>> rutgers!petsd!tsdaig!ka2qhd!n2ihn <<<<<<<<<<<<<<<<<<<<<<<< Mods for: 735,720,745,751,430,940,440,2600 ht ICOM IC-735 To unlock the transmitter: cut diodes D33 and D34 that are standing on end near the microprocessor section toward the rear top of the radio. ICOM IC-720 Transmitter is unlocked by snipping the light blue wire that's at the very end of the top hatch cover to the left middle side of the transceiver. ICOM IC-745 Locate the RF board on the side of the radio and cut the light brown wire at jack 7., which is going to pin 1. Your transmitter is now unlocked. ICOM IC-751 Locate the RF board on the side of the radio and cut the black wire going to pin 1 of jack 2. Your transmitter is now unlocked. (This mod also described in _73_, July 1985 p. 12.) KENWOOD 2600 Locate the two diodes standing on end with Teflon covering the top part of their leads (which at one time were soldered together, broken, and then resoldered). Simply clip these two leads to unlock the transmitter, but be sure to reset the microprocessor by pushing the reset button before the set is capable of transmitting on any frequency at 150 MHz. KENWOOD TS-430S Unplug 3-wire plug on the RF board that mates with socket 10. When looking at the top front of the radio, it's to the left front side right beside a larger white plug. You'll need to carefully examine the circuit board and locate the number 10 with a circle around it to insure you have the right plug. KENWOOD 940 Locate IC number 109. Now find diode 130 and cut it for all-band transmit. If you want just MARS coverage, locate IC 111 and 112, and snip diode 135 beside it. KENWOOD TS-440 West,Gordon: "Kenwood 440 Modifications" _Popular Communica- tions_, October 1987 p. 62. Illustration captions: 1. Remove 17 screws holding on the bottom and top covers. The bottom cover comes off, and the top cover is carefully removed and put next to the radio. It is till connected via the speaker wire. 2. Gain access to the front of the unit by removing two top side screws and loosening two bottom side screws. This allows the front assembly to swing open. 3. Remove the shiny silver control board protection plate. This requires removing two screws on the top and three screws on the bottom. Lift the plate out completely. 4. Locate diode D-80 in the bottom left-hand corner. Snip it for all-band transmit. 5. Now locate D-66 and snip. It adds 10 Hertz readout to your digital frequency display. 6. Carefully reassemble the control plate using a magnetized tiny screwdriver to hold the five tiny screws in place. Don't pinch any wires. Also, close up the front and replace the top and bottom covers with 17 screws. 7. Connect power. Depress A=B switch and turn on the power simultaneously. This resets the microprocessor for all-band transmit and 10 Hz frequency display. TS 430 TRANSMIT AUDIO MOD Add more treble to your TS430S by removing c96 (.015 MFD ) on the if unit board. The removal of C96 adds about 3DB of precense to your transmit audio.. ......From Kenwood Net... INADEQUATE VOX GAIN Simply increase your VOX gain in your 430 by changing R23 (located next to the vox gain control) from a 10K 1/2 watt resistor to a 3.3 K 1/2 watt resistor. VARIABLE MICROPHONE GAIN IN FM MODE Remove the pins from the plastic housing of plug 19 (located next to the VOX gain control) and carefully insert them with pins 3 & 4 of plug 5 on the if unit. Mt to the VOX gain control) and carefully insert them with pins _ & 4 of plug 5 on the if unit. Make sure the shielded leads correspond with each other. This will also give you the ability to use your speech processor on FM. ALL INFO COURTESY OF THE KENWOOD NET........ Note: I haven't tried or verified any of this, proceed at your own risk. WA2ISE IC M-700, 757GX MODS: YAESU 757GX Lert,Peter: "Bootleg HF Radios," _IFR_ magazine, Premiere issue, 1985, p. 12. Open the radio and flip an unmarked but quite accessible switch. Article also describes airborne HF antennas. ICOM M-700 Marine Transceiver Despite that the literature says, no lock-out is employed. For ham frequencies on 40, 80 or 160 meters, set the mode switch to the hard left position of "A3," to enable the lower sideband filter (all marine HF uses upper sideband). TM-701A REPEATER CROSS-BAND MODIFICATION (REVISED) This Mod is from KENWOOD Perform The following modification to allow the TM-701A to operate in the repeater cross-band mose. MODIFICATION: 1. Disconnect the power supply and antenna. 2. Remove the top and bottom covers (12 screws). Disconnect the speaker wire from the transceiver. 3. Locate the green jumper wire shown in figure 1. Using a sharp pair of wire cutters, cut the jumper in half. ______ ______________ | |_____ | TOP <|---- Green Jumper | | | | | Heat sink | | | | | \ / FIGURE 1 CATUION: Cutting the green jumper allows the TM-701A to transmit from 142 to 151.995 MHz. Protect your license by only using frequencies that you are authorized to transmit on. 4. Solder a jumper wire to the foil side of the TX-RX board as shown in Figure 2. ______ ^ __| |________|________________ | Display side | | X ...... | X = Screw | X ...... | | - ----| | | .............. | <---------- ADD Jumper . | Pin #3 :____________| : FIGURE 2 5. Assemble the transceiver by reversing steps 1-2. 6. Reset the microprocessor by holding in the MR key as the power is turned on. The repeater cross-band operation allows the TM-701A to receive on one band and re-transmit the signal on the other band. The TM-701A alternately displays the two bands until a signal is received. The transceiver will then display the band that is re-transmitting the signal. The shift function cannot be used during the repeater cross-band operation. If the TONE or CTCSS function is required, only one EIA tone can be used for the two bands. OPERATING PROCEDURE: 1. Select the operating frequencies for both bands. 2. Set the squelch control to the threshold point. The TM-701A will transmit in the repeater cross-band mode if the squelch control is set too low or a signal is received. 3. Place the transceiver in the duplex mode (F + DUP). 4. Press the F key for longer than one second. The F indicator will flash. 5. Press the LOW key. The transceiver will now enter the repeater cross-band mode of operation. 6. To cancel the operation and return to the VFO mode, press the VFO key. Article 11986 of 11995, Fri 11:44. ~Subject: UK 'Student' license? ~From: PJML@UK.AC.NERC-WALLINGFORD.IBMA (Pete Lucas NERC-SWINDON U.K. @ The Internet) (34 lines) More? [ynq] FT209 RH: The magazine article says to jump pins 1, 7, 9, 10, 11, 13, and 16. In every 209RH I've opened, pins 1, 9, and 13 are already jumped. Adding jumpers 7, 10, 11 and 16 allows "out-of-band" transmission. But the receiver becomes thoroughly confused, and is not tunable. The solution: DON'T jump 11 and 16. So the final steps are: 1) Add jumpers to 7 and 10. 2) Give the VCO can a 1/2 turn clockwise if you're moving to higher freqs. 3) Reset radio and reprogram rcv and xmit freqs, and rptr offset. FT 212RH extended freq. coverage mod. Remove the bottom and top covers and remove the front panel cover. You must then remove the front board by carefully unpluging it (try not to touch the lcd display). On the back of this board which is the control unit locate jumpers 1 through 12 and unsolder any that are soldered. All jumpers must be open (1-12 only). Reinstall the control unit and just turn on the radio for a few seconds. now turn it off again and remove the control unit again and solder jumpers 3, 4, 5, 11 only. Put everything back together and apply power. The display will read 000. Push the MHz button and rotate the main dial until 132.000 reads on the display, then press D/MR once. Now press again the MHz button and rotate to 180.000 and press the D/MR again. the radio is now programmed to operate from 132 to 180 mhz. mine has tx and rx through the entire spectrum with excellent sensitivity from 136 to 178. Dont forget that transmitting outside the amateur band is not allowed so please consult your local athorities for a special permit. 73s and have fun.......de SV0DR @ SV1IW John Heaton YAESU FT-23R EXTENDED FREQUENCY RANGE: "Circumcising" the FT-23R is remarkably simple. Removing one solder blob (pad #7, clearly marked, 10 o'clock position from the speaker, 9 o'clock from the microprocessor) lets the radio receive and transmit from 140.0 to 163.995 MHz. The two circuit boards with surface-mount components are uncluttered. When opening the radio, be careful not to lose the tiny coil-spring inside the battery-release button. I haven't measured receiver sensitivity, nor do I know about performance in big-city RFI; the FT-23R is considerably more sensitive at 162-MHz weather frequencies than is my modified Icom IC-02AT. Hello to all the owners of the FT-411 OF YAESU, I have this Hand held, and by playing with it, I discovered a nice trick to increase it frequency coverage. It is so simple that you don't even have to open your hand held. All you have to do is: 1. Make sure that the power switch is off. 2. press the UP arrow and DOWN arrow together, at the same time (those keys are also called A, and B. and they placed at the upper right side of the keyped) 3. Keep pressing both buttons and turn the power on. That's all. Now you can receive 130-174Mhz, and transmit 140-150Mhz CAUTON: When you do this modification the memories can be erased. Ayhow I think it is not the end, and there are some more options. If you do have some more information about this Hand held, Please leave me a msg with it. Tnx, AVIAD, 4X6TL@4Z4SV 1508z, 635 msgs, #24083 last @KD6TH-4 MailBox> FT 411 OUT OF BAND MODIFICATIONS. --------------------------------- 1) Open the front cover 2) Locate the C.P.U. unit (it is located on the front cover ). 3) Locate Jumpers 1,2,3 and 4 , These are the band setting Jumpers 4) Jumpers No 1,2 and 4 should be disconnected ,and Jumper No 3 should be connected. 5) Close the radio . 6) Apply power to the radio and turn it on. The display will initialize with memory No 1 flashing and the frequency display will show 1.000 7) Now , adjust the display to the desired lowest receive frequency When done ,press VFO. The memory CH will now show 2 flashing . 8) Adjust the display to the desired highest receive frequency When done press VFO . The memory CH will now show 3 flashing . 9) Adjust the display to the desired lowest transmit frequency When done ,press VFO. The memory CH will now show 4 flashing 10) Now , adjust the display to the desired highest transmit frequency When done ,press VFO. The rig is now set for your programed band on transmit and receive. COMMENTS ------- 1) After the rig was programmed to the band and you want to change it to other ranges you will have to open the rig again and disconnect Jumper No 3 then to apply power to the radio ,turn it on again open it again ,connect Jumper No 3 back and repeat from steps 5 . Any comment and other information would be appreciated. Good Luck Aviad 4X6TL@4Z4SV disclamer: I have not tested or verified the above, proceed at your own risk. WA2ISE .......................................................................... . Mark Bramwell, VE3PZR . . . . The University of Western Ontario Bitnet: MBRAMWEL@UWO.CA . . School of Business Administration Packet: VE3PZR @ VE3GYQ . . London, Ontario, N6A 3K7 Phone: (519) 661-3714 . .......................................................................... I was unhappy with the FT-411's "3" mode because the frequency had to be entered starting with the 100 MHz digit, and the ARS function would not work. I now use it in the "2" (normal) mode with the following mod. I used the "clone" mode to dump the FT-411's ram to a computer. It's 9600 baud, 1 start bit, 1 stop bit, CMOS logic. 544 bytes are dumped when the up arrow is pressed. Starting with byte $211 are the upper and lower transmit and receive frequencies, stored in BCD. I changed these to the limits I wanted. My FT-411's upper PLL limit is 195.4 MHz, so I used 195 MHz. The lower limit MUST remain set to 130 MHz (magic number) or the keyboard entry of frequencies will start with the 1 MHz digit .VS. the 10 MHz digit. To put the data back into ram, just press the down arrow and send the new 544 bytes to the FT-411. You could also just clone an H.T. that has the limits you want. You can not clone a mode "3" H.T. to a mode "2" H.T., however. The mode is contained in the first byte, which must match. Bill Pherigo WR0Y FT-470 Here is a reposting of the mod to extend the receive range of the new Yaesu dual band handie to 130 - 180: 1. Turn radio OFF. 2. Hold down both UP and DOWN arrows. 3. Turn radio back ON. I will trade the mod for VHF xmit for one to open up UHF for recieve...I want to listen to UHF public service (450-470). To enable VHF transmit: 1. Open the radio such that the two halves open like a sandwich. 2. Locate the internal lithium battery 3. Locate several solder pads to the left of the lithium battery. 4. Just to the top left of the lithium battery is ONE vertical solder pad. It is almost under the top left edge of the battery. 5. solder a jumper accross this pad. Notes: The other solder pads do several things, none of which seemed interesting to me: one set VHF band to 144-146, one replaces 2m band with 1260Mhz (would be nice if there was a 1260 Mhz RF module available...), two others seem to disable the squelches for the separate bands...etc. like I said, not too interesting. Also note that for some reason the automatic repeater shift (- offset below 147, + above etc...) goes away when you enable VHF xmit using this mod. I guess you can't have your cake and eat it to. Oh well... 73! Keith McQueen 1116 S. 250 E. Orem, Ut. 84058 IC-24AT At the request of several interested hams, I am posting the modification instructions for the Icom IC-24AT. This set of instructions originated from Icom America and was downloaded from the Icom Library of HamNet (Compuserve). Ken WA6TTY (kenw@col.hp.com) ----------------------------------------------------------------------- IC-24AT Undocumented Features - (from ICOM) The IC-24AT dual band handheld had three additional features that are not described in the owners manual. These have been left out of the owners manual because some countries restrict the use of the radio in these modes. AM AIRCRAFT RECEIVE PLUS 740 to 960 MHz RECEIVE Remove D13 from the main logic board (this diode may already be removed by ICOM in some units). This diode may already be removed in some radios. D13 is on the main logic board and is a discreet diode (one of the two in the radio) near the center of the board. It is the left discreet diode of the two on the board when the radio is open and held with the controls away from you. Simultaneously hold "Light", "B", and "#" keys depressed and turn power on. It is important to note that the radio will not meet specifica- tion on the out of band receive frequencies that are enabled with this modification. DIRECT KEYBOARD ENTRY of 100 MHz FREQUENCY Simultaneously hold "Light" and "3" keys depressed and turn power on. CROSS BAND REPEAT (simplex) Remove D14 from the main logic board (this diode may already be removed by ICOM in some units). The diode is a discreet diode to the right of D13 (from above) and directly beside it. Simultaneously hold "Funct" depressed and push "C". To turn on cross band repeat: Hold "Funct" depressed then push "5" and then push "D". To turn off cross band repeat simultaneously hold "Funct" and "D" depressed. 2-14-90 Article 17974 of 17989, Thu 12:07. ~Subject: Re: IC-24AT Receive Mods ~From: kenw@col.hp.com (Ken Wyatt @ HP Colorado Springs Division) (33 lines) More? [ynq] Following the frequency expansion modification (as specified by Icom), a sample IC-24 was recently tested for tuning range and input sensitivity for an S9 signal. While the sensitivity measurements should not be directly compared with the manufacturer's specifications (usually measured reference to a signal-to-noise quieting ratio), this "quick and dirty" data should give you a good idea of the sensitivity to a medium-strength signal. Tuning Range Mode Band Sensitivity for S9 Signal 74 - 107.995 MHz (fm) VHF range approx 1 mV 108 - 136 MHz (am) VHF range 10 - 30 uV 138 - 240 MHz (fm) VHF range 1 uV - 1 mV (1) 250 - 302 MHz (am) VHF range 50 uV - 1 mV (2) 310 - 354.995 MHz (fm) VHF range 50 uV - 3 uV (2) 355 - 409 MHz (fm) UHF range 3 - 10 uV 417 - 490 MHz (fm) UHF range 1 uV - 100 uV (3) 805 - 955 MHz (fm) UHF range 10 - 100 uV Notes: (1) The sensitivity from 138 - 150 MHz was 1 uV. From 150 - 240, the sensitivity decreased almost linearly from 1 uV to 1 mV (with input voltage plotted logarithmically). (2) The sensitivity increased almost linearly for both these ranges (with input voltage plotted logarithmically). (3) The sensitivity plot looked like a "U" with the bottom of the "U" corresponding to the range 440 - 450 MHz (1 uV). The sensitivity then got worse below 440 and above 450. (Tests courtesy of WB6GTM) Per the posted information and current discussion on the modification of the **new** ICOM 24AT dual band HT: The Modification for freq. coverage extension: 1) Remove Diode D13 2) Keyboard [B,#,LIGHT] & Power-ON Does work... FOR RECEIVE-ONLY! The process is relatively simple; considering that most of the entire radio is surface-mount parts... It turms out that Diode D13 is one of two "normal" sized diodes on the LOGIC BOARD easily accessed and cut when the radio is opened... (Two "standard" diodes are found below the logic IC1 by about a 1/3inch, with IC1 at the top, looking at the diodes D13 is the one on the left.) Result: Recieve results (rough-info for about 6 hours of use after mod) VHF: PLL begins to lock in at about 75mhz ... and goes out of lock at about 280mhz (display will go 0mkhz to 355mkhz) UHF: PLL begins to lock in at about 355mhz and goes out of lock at about 500 mhz... PLL begins to lock in at about 795mhz and goes out of lock at about 975 mhz... (display will go 355mhz to 1310mhz) Actual use/operation: Aircraft: (108-136) seems to detect AM ok... within 2 miles of Ohare Intl(ORD) recieve of ground 121.--- moderate receive of ATIS 134.--- good recieve of tower and approach moderate seems that high-end of band receives better. "looks like for a pilot who desires to monitor ops at the port prior to run-up or whatever should work fine) 2m HAM: As shipped. VHF HighBand (150-176): seems pretty hot- unit is shipped rec'ing this stuff 220 mhz: VERY Dead receive at these freq. hears only very-local transmitters **ALSO above 200mhz step rate is no smaller than 12.5khz !!SO NOT ALL channels can be tuned on freq- (UUCH!) 70cm (420-450): Fine UHF (450-476): Hot reciever! - best ham mod'd receive better than IC32AT mod rec... 470+ mhz works well- chicago has allocations of Public service and business in 470-476 ...and 24at works well 800mhz (convential/trunking): Ah..it hears the band- perhaps about the same as most scanners- Not as hot as above bands- BUT actual fairly useable! 870-890 (cellular): Yes, but channel step rate is 12.5khz and cellular is on 30khz, so can not be on exactly every channel. 900mhz: Did not check out much here... did hear a few chicago trunking systems at the 935 trunking band--- *also a lot of cellular images present. Bottom Line--- ICOM 24AT is a NEAT VHF/UHF/800mhz reciever and 2m/70cm HAM radio in ONE. The modification (D13 cut) provides a manner to receive extended band coverage, without worrying about accidental transmission in other services; [however I would like to see 420-440 xmit at least as I have repeater link/control in that part of the HAM BAND; also 220 mhz freq&xmit would be real neat; as well as 900mhz xmit which a few repeaters do exist in the area] ((((one only wonders what the next generation of HTs will do???)))) Larry Schroeder -- AT&T Bell Laboratories -- Naperville, IL KA9KDC 708-979-1020 IC32A MODIFICATIONS Originally prepared by N0ION, modified by N0AMP. | This is a view of the interior (front side) after | the front of the case has been removed (4 screws / \ in back, 2 screws near PTT switch loosened only). | | +-+ +--+ | | | | | | Carefully disconnect speaker/mike cable from PC +------------------+ board to allow front cover to be fully opened. | TOP | | | NOTE: Battery should be disconnected. Use ESD | | protection (grounded wrist strap, etc.). | | | | | | | | | | | | | | | | | +-+ | | | | | 5 positions on PC board | | | | for diodes (see below for | BOTTOM +-+ | details) +------------------+ | | | | | BATTERY | | | | | +------------------+ This shows diodes as installed at the factory. TOP +--+ +--+ | | | | D907 +--+ +--+ +--+ | /| +--+ | |---|< |---| | D913 Removing this diode results in expanded UHF +--+ | \| +--+ coverage. Coverage is from about 430-460 Mhz. +--+ +--+ | | | | D908 +--+ +--+ +--+ | /| +--+ | |---|< |---| | D912 Removing this diode results in enabling +--+ | \| +--+ the unit as a cross-band repeater. +--+ +--+ | | | | D??? Installing diode here (same direction as others) +--+ +--+ permits direct entry entry of the 10Mhz digit. BOTTOM Icom Service Bulletin #13889-005 The IC-32AT has the capability of being used as a cross-band repeater. This function is not enabled as the unit is shipped from the factory. To enable this function perform the following steps: 1- Cut D912 on LOGIC UNIT. (see above figure) 2- Push and hold the (FUNCTION) switch. 3- Push the (C) key. 4- Push the (6) key. 5- Push the (D) key. 6- Release the (FUNCTION) switch. To cancel "MINI REPEATER" perform the following steps: 1- Push and hold the (FUNCTION) switch. 2- Push the (D) key. 3- Push the (C) key. 4- Release the (FUNCTION) switch. TH-25AT TH-45AT Ok, I've promised it for a long time and now it's time to live up to my promises. Here are some mods for the TH-25AT and the TH-45AT. Please note that I do not encourage transmitting on a frequency for which you do not have a license, nor do I encourage transmitting on a non-amateur frequency without FCC type accepted equipment (in the United States). Lament: when are the Japanese going to produce a 440 FM HT for the US market that has receive coverage outside the US amateur band? Lord knows that there's a market for it - there's MONEY to be made. First let me recommend that you buy the service manuals for these radios. The service manual is not expensive (about $15 I think) and it will greatly help you in performing these modifications. Look at the schematic for your radio. In the lower left hand corner is an IC labled IC2. This is an ASIC microprocessor. At the lower right hand corner of this uP are several diodes and pull-up/pull-down resistors. They are D4, D3, R19, R18, R28, R20, R21, R22, R25, R26, and a couple of resistors that are not even on the schematic that attach to B2 (pin 51 on IC2) and B3 (pin 50 on IC2). The TH-45AT schematic shows R23 on the ASIC uP pin B2. The schematic for the TH-25AT shows: R18-R21 R25 R26,27 R28 R36 TH-25A M,M2 -12 O X X X X TH-25A M3,M4,X -23 O X X O X TH-25AT K -11 O O X X X TH-25AT M,M2 -12 O X X X X TH-25E T -52 X X O O O TH-25E W -62 X O O O O And the schematic for the TH-45AT shows: R19-R21 R22 R23 R25 R26,27 R28 R36 TH-45A M1,M2,X -21 O O O X X O X TH-45A M3,M4 -22 O X O X X X X TH-45AT K -10 O X O X X O X TH-45AT M1,M2 -21 O O O X X O X TH-45AT M3,M4 -22 O X O X X X X TH-45E T -51 X O X X O X O TH-45E W -61 X O X O O O O where O means USED, and X means NOT USED. Some of the above codes are: K USA T England X Australia M Other Areas These components are found on the flexible circuit board under the display. To get to them, take the radio apart. Some unsoldering of obvious grounding wires may be necessary. You will see where the flexible circuit board plugs into a socket on the main circuit board. Before unplugging it, make sure you know what's in the memories, because they will be lost. Unplug the flexible circuit board and unfold it so that the components are accesable. One of the fold-out parts of the flexible board will look something like this: +----------------+ | R R R D3 R R | | 2 2 2 7 2 | | 5 3 2 1 | | | | R O O R20| The O's are solder pads. | 2 O O R19| | 6 O O R18| | O O R28| | | | R | | D4 6 | | +-------+ | | | | The fold out board is actually square, but with only characters for graphics, I couldn't draw it that way. On both radios, R36 is for the European tone burst to "whistle up" repeaters. On both radios, D4 is for selecting the type of display. With D4 in, the display is normal. With D4 removed, the display is a channel display. D3 is for selecting VHF or UHF. With D4 in, the radio thinks its a VHF radio. With D4 removed, the radio thinks its a UHF radio. Don't change this on your radio. On the TH-25AT: (All frequencies given in MHz.) R22 in R28 out This is how the radio is delivered in the USA. TX 144-148, RX 141-163 (I think). R22 out R28 in The radio tunes from 142-151. This may be the modification given to US MARS members. I don't remember where the unit will transmit. It may or may not transmit outside the range from 144-148. R22 in R28 in The radio tunes only from 144-148. R22 out R28 out Frequencies may be selected from 100-200 MHz (on the display only - your PLL will not lock up in this entire range). In addition, TX is possible where your PLL locks up. R25 out Removing R25 disables automatic offset selection. R23 and R24 are used for selecting the step size for tuning. I can't remember which positions are for which step sizes, and alas I didn't write down what I found. If you want to play with this, go ahead. On the TH-45AT: (All frequencies are given in MHz.) R18 in R28 in This is how the radio is delivered in the USA. The radio covers 438-450 MHz. R18 in R20 out The radio is prohibited from tuning outside 440-450 MHz. R18 out R28 in The radio will only tune from 215-230 MHz. Note that the PLL would not lock up! (What did you expect?) Could it be possible that Kenwood originally planned a 220 version of this radio, but then scrapped their plans? R18 out R28 out The radio will tune from 200-500 MHz (on the display only - your PLL will not lock up over this entire range). Transmitting is possible anywhere your PLL will lock up. I have found a quick and easy way to retune your PLL (in the TH45-AT) with a minimum of test equipment. All you need is a scope and a small tuning tool. First, take off the battery pack holder plate. Then, remove the silvery sticker covering the tuning pot access holes. If the radio is positioned on its back, with the top folded over so that the touch tone pad is also facing down, the test point you want (TP1) is on the bottom half of the radio, near the center (left to right), and close to the battery; the tuning pot you want (TC1) is on the bottom, and closest to the PTT switch. Under no circumstances change the tuning of TC51. This is used to calibrate the output of the radio with the display the radio is giving; you don't want to mess with it. Once again, the Service Manual makes it very clear where these points are, if you are having trouble with my descriptions. On with retuning the PLL. With the radio on, and receiving, monitor the voltage and the waveform on test point TC1. Tune the radio DOWNWARDS in frequency until the PLL unlocks. Note that the radio will beep when this happens, and the waveform on TP1 will change. Tune the radio about 1 MHz higher so that the PLL locks up again, and note the voltage on the testpoint, TP1. Now, tune the radio to the LOWEST frequency that you want to be able to receive. Adjust TC1 until the voltage on the test point TP1 is the same as what was noted earlier. Button the radio back up, and you're done. You will not be able to tune the PLL to any range you want. There are limits. On my radio, I have been able to retune the radio so that I can recieve from 439.2-468.6 MHz with a set of batteries fresh out of the charger. The tuning range will probably diminish as the battery voltage decreases. I have not retuned the PLL on my 2m HT, but I'd imagine the same technique will prove fruitful. I may have some more information on these radios someplace. If I can find it, I will add to this posting, and post it again with the updated information. Enjoy. ----> Abortion is murder; Affirmative Action is discrimination. <---- In the rare case that original ideas Kenneth J. Hendrickson N8DGN are found here, I am responsible. Owen W328, E. Lansing, MI 48825 Internet: hendrick@frith.egr.msu.edu UUCP: ...!frith!hendrick Jim Vienneau, Sun Microsystems Inc - Billerica, MA Email: jvienneau@east.sun.com Amateur Radio: WB1B Good old Ma Bell (well old anyway): (508)671-0372 Thanks Jim. Later on, I reposted a more detailed description of how to do these mods, with more information. Here it is again for those who missed it the first couple of times around. Hit 'n' now if you've already read this and don't want to waste your time. Please note my new email address, in my .sig at the very end. 73 In the past, I posted some mods for the Kenwood TH-X5AT series of HTs. My previous posting had some minor errors, and left some questions unanswered. Yesterday, I helped a friend modify his TH-45AT, and some of these questions were answered. This posting will clear up the problems in the previous posting, as well as contain all of the important information from the previous posting. You may delete your previous copy of this information, and replace it with this one. --------------------------------------------------------------------- Copyright (C) Notice: Some people have been taking information posted to this network, publishing it, and selling it. Not only is this immoral, it is also illegal. You may not do this. I give everybody the right to copy this material, and give it to others. You must not sell it. You may NOT include this information in a newsletter or compendium that you charge for, but you may incude it in a free newsletter or compendium. You may NOT distribute this information on a computer bulletin board system that users are charged any fees for, but you may distribute this information on a computer bulletin board system if you provide the service free of charge. You must not alter the information provided here in any way, including removing this copyright notice and/or removing the authors' name and/or e-mail address at the end of this message. --------------------------------------------------------------------- Here are some mods for the TH-25AT and the TH-45AT. Please note that I do not encourage transmitting on a frequency for which you do not have a license, nor do I encourage transmitting in the United States on a non-amateur frequency with equipment that has not been FCC type accepted. This is illegal in the United States, even if you have a license to transmit on the given non-amateur frequency. First let me recommend that you buy the service manuals for these radios. The service manual is not expensive (about $15 I think) and it will greatly help you in performing these mods. Before performing any of these modifications, make sure you know what's in your memories, because they will be lost. --------------------------------------------------------------------- Look at the schematic for your radio. In the lower left hand corner is an IC labled IC2. This is an ASIC microprocessor. At the lower right hand corner of this uP are several diodes and pull-up or pull-down resistors. They are D4, D3, R19, R18, R28, R20, R21, R22, R25, R26, and a couple of resistors that are not even on the schematic that attach to B2 (pin 51 on IC2) and B3 (pin 50 on IC2). The TH-45AT schematic shows R23 on the ASIC uP pin B2. Another important resistor is R27; on the schematic it is located next to the frequency selection switch EN1 above IC2. A less important resistor (for modification purposes) is R36; on the schematic it is located to the right of IC2 in line with the top edge of IC2. The schematic for the TH-25AT shows: R18-R21 R25 R26,27 R28 R36 TH-25A M,M2 -12 O X X X X TH-25A M3,M4,X -23 O X X O X TH-25AT K -11 O O X X X TH-25AT M,M2 -12 O X X X X TH-25E T -52 X X O O O TH-25E W -62 X O O O O And the schematic for the TH-45AT shows: R19-R21 R22 R23 R25 R26,27 R28 R36 TH-45A M1,M2,X -21 O O O X X O X TH-45A M3,M4 -22 O X O X X X X TH-45AT K -10 O X O X X O X TH-45AT M1,M2 -21 O O O X X O X TH-45AT M3,M4 -22 O X O X X X X TH-45E T -51 X O X X O X O TH-45E W -61 X O X O O O O where O means USED, and X means NOT USED. Some of the above codes are: K USA T England X Australia M Other Areas These components are found on the flexible circuit board under the display. To get to them, take the radio apart. --------------------------------------------------------------------- (1) Only 8 screws must be removed from the case to take the radio apart; these are the 4 screws that hold the battery clip on, the 2 screws on the back half of the case near the PTT switch, the screw on the back of the case under (and in line with) the BNC connector, and the screw on the back half of the case adjacent to the external speaker jack. (2) After removing these 8 screws, remove the front half of the case from the back half. You may unconnect the blue plug from the touch tone circuitry on the front half of the case to make further work on the radio more convenient, but it is not necessary. (3) Place the radio back side down with the antenna away from you. Now, unsolder the two grounding wires from the plate which covers much of the radio's circuitry. These wires are near the top of the plate and will be quite obvious. (4) Next, remove the 7 screws that hold this plate on. 5 of the screws for this plate are up on top and are quite obvious; the other 2 are at the bottom of the plate, and may be hidden by your CTCSS unit. Remove the plate. (5) Remove the red plug with about 7 wires that connects just under the volume and squelch switch. (6) Remove the screw that holds the PTT/LAMP/MONI switch assembly; this screw is on the left side of the radio just under the PTT switch. (7) Remove the two screws that hold the top assembly to the back case of the radio; these two screws are on either side of the orange flexible circuit board coming from the top assembly and plugging into the back case of the radio. You may need to use a screwdriver or stick to move the orange flexible circuit board out of the way in order to see these final two screws. (8) Unplug the orange flexible circuit board from the back case. At this point, the whole top assembly should come free quite easily. The BNC connector will stay attached to the back case, and the whole top assembly will come up over it. (9) Unfold the flexible circuit board and unfold it so that the components are accesable. One of the fold-out parts of the flexible board will look something like this: (the component side is shown up) +----------------+ | R R R R D3 R R | | 2 2 2 2 7 2 | The O's are very large solder pads. | 5 4 3 2 1 | | | | R O O R20| Not all components will be installed on your | 2 O O R19| circuit board. | 6 O O R18| | O O R28| | | D3 & D4 are two diodes in a three terminal | R | package. The anodes of the diodes are in | D4 6 | common. | +-------+ | | | | The fold out board is actually square, but with only characters for graphics, I couldn't draw it that way. It comes out reasonably square on a printer with 10 characters/inch and 6 lines/inch. On both radios, R27 is located to the right of the four blue buttons on the back of the radio (M CTCSS SHIFT REV). You should be able to see this on the back of the now removed top assembly. On both radios, R36 is for the European tone burst to "whistle up" repeaters. R36 is located on another portion of the flexible circuit board, closest to pin 1 of IC2. IC2 is the IC closest to the portion of the flexible circuit board shown above. Most users will not want to change R36. --------------------------------------------------------------------- Here is the function of the diodes and pull up or pull down resistors (for both the TH-25AT and the TH-45AT unless otherwise specified): D4 selects the display type. installed: channel display removed: normal frequency display You probably don't want to install this. R6 is the pullup resistor for D4. Do not remove it, so that if D4 is removed, pin 44 of IC2 will be properly pulled up. D3 selects VHF or UHF. installed: VHF removed: UHF You definitely don't want to change this! R7 is the pullup resistor for D3. Do not remove it, so that if D3 is removed, pin 45 of IC2 will be properly pulled up. R25 selects automatic offset selection. installed: automatic offset selection enabled. removed: automatic offset selection disabled. R25 seems to have no effect on the TH-45AT. R23,27 frequency selection step size. Frequency selection step sizes is only known for TH-45AT. R23 R27 frequency selection step sizes: --- --- --------- --------- ---- ------ out out 5 and 10 kHz in out 5 and 25 kHz (TH-45AT default) out in 5 and 12.5 kHz (author's preference) in in 10 and 20 kHz R23 probably has no effect on the TH-25AT. I never checked. I was quite satisfied with the 5 and 10 kHz step sizes for the TH-25AT. I never tried changing R27 to see what would happen. R24 ? something with the CTCSS tone ? installed: When a TX offset is selected, the CTCSS tone is always transmitted. The TONE button does not work correctly. When the TONE button is depressed, the display goes to 430.000 c, and nothing seems to work. (A "c" is displayed in the channel number position.) The action of the TH-25AT is unknown. removed: CTCSS tone selection works correctly. Both the TH-25AT and the TH-45AT are delivered this way. You probably don't want to install this. R19 function unknown. R19 is not installed in the European version. R20 function unknown. R20 is not installed in the European version. R21 function unknown. R21 is not installed in the European version. R19, R20, and R21 are all in parallel. Thus, if any of them is installed, it is like all of them are installed. R26 function unknown. R26 is installed in the European version. On the TH-25AT: R22,28 select RX and TX frequency range. R22 R28 RX range TX range --- --- -- ----- -- ----- in out 144-148 141-163 (USA default) in in 144-148 144-148 out out 100-200 100-200 (only where your PLL locks up.) out in 142-151 ???-??? R18 exact function unknown. installed: as delivered in USA. removed: TX disabled from 146-148. The RX and TX frequency range based on R22 and R28 are unknown if R18 is removed. On the TH-45AT: R18,28 select RX and TX frequency range. R18 R28 RX range TX range --- --- -- ----- -- ----- in out 440-450 440-450 in in 438-450 438-450 (USA default) out out 200-500 200-500 (only where your PLL locks up.) out in 215-230 215-230? (PLL won't lock up.) R22 TX offset selection installed: 1.6 MHz offset (perhaps for 220, or Europe) removed: 5 MHz offset (USA default) --------------------------------------------------------------------- PLL adjustment --- ---------- I have found a quick and easy way to retune your PLL (in the TH45-AT) with a minimum of test equipment. All you need is a scope and a small tuning tool. First, take off the battery pack holder plate. Then, remove the silvery sticker covering the tuning pot access holes. If the radio is positioned on its back, with the top folded over so that the touch tone pad is also facing down, the test point you want (TP1) is on the bottom half of the radio, near the center (left to right), and close to the battery; the tuning pot you want (TC1) is on the bottom, and closest to the PTT switch. Under no circumstances change the tuning of TC51. This is used to calibrate the output of the radio with the display the radio is giving; you don't want to mess with it. Once again, the Service Manual makes it very clear where these points are, if you are having trouble with my descriptions. On with retuning the PLL. With the radio on, and receiving, monitor the voltage and the waveform on test point TC1. Tune the radio DOWNWARDS in frequency until the PLL unlocks. Note that the radio will beep when this happens, and the waveform on TP1 will change. Tune the radio about 1 MHz higher so that the PLL locks up again, and note the voltage on the testpoint, TP1. Now, tune the radio to the LOWEST frequency that you want to be able to receive. (Be very careful when you adjust TC1. If you are not careful, you could break TC1 loose. This will cause your radio to have microphonics. Mechanical vibrations will change the value of this capacitor, and thus change the tuning on the PLL. If you encounter this problem, you can repair it by dripping wax through the small hole onto TC1, or by replacing TC1. It is of course better not to break it in the first place.) Adjust TC1 until the voltage on the test point TP1 is the same as what was noted earlier. Button the radio back up, and you're done. You will not be able to tune the PLL to any range you want. There are limits. On my radio, I have been able to retune the radio so that I can recieve from 439.2-468.6 MHz with a set of batteries fresh out of the charger. The tuning range will probably diminish as the battery voltage decreases. I have not retuned the PLL on my 2m HT, but I'd imagine the same technique will prove fruitful. --------------------------------------------------------------------- In the rare case that original ideas Kenneth J. Hendrickson N8DGN are found here, I am responsible. Owen W328, E. Lansing, MI 48825 Internet: kjh@pollux.usc.edu UUCP: ...!uunet!pollux!kjh "Before Abraham was born, Kenneth J. Hendrickson N8DGN I AM!" Jesus of Nazareth 1709 S. Bonnie Brae St., LA, CA 90006 Internet: kjh@usc.edu UUCP: ...!uunet!usc!pollux!kjh IC-28A, IC28H, TH-215A MODS: TH-215A handheld transceiver out-of-band modification: 1. Remove two screws from belt clip 2. Remove 4 screws from back of radio 3. Slide front assembly off 4. Locate set of 4 jumpers: (top front inside) +--------------------------------------+ | | | | | +--------+ | | | | | | | | | | +--------+ | | | | +--------+ | | | | | J4: intact | J4 o---o | | | J3: cut | J3 o) (o +--------+ | J2: cut | J2 o) (o | J1: cut | J1 o) (o | | | | | | | | SPKR | | | | | | mic | | | +--------------------------------------+ 5. Reassemble radio. 6. Reset microprocessor: Turn radio on while simultaneously pressing both _F_ key and _ENTER_ key. -- DISCLAIMER: I do not own a TH-215A and have not verified the above information. Hopefully, the modified frequency range includes 162 MHz weather-broadcast freqs. Remember, it is ILLEGAL to transmit outside the ham band with non-FCC-type-accepted equipment, even if you are licensed to use such frequencies. ICOM IC-28A AND IC-28H To make the IC-28 transmit 138-174 MHz, cut D21 (no retuning required). D21 is a tiny glass diode standing on-end near the center of the upper circuit board, accessible by removing the top cover. The IC-28 is the only convertible ham rig I know that covers the 170-MHz federal government (including national park) frequencies. TH-77 I don't know about TH-77A which I think is an export version of TH-77, but I can give some information on TH-77, which I own. This set originally can TX/RX on 144-146MHz, and 430-440MHz. By cutting a green line about an inch long connecting between a capacitor and pin 4 of CPU(HD404608H) enables receiving on 118-174MHz, 335-512MHz, and 800-950MHz. There is another modification which let you transmit on wider range of 136-174MHz, and 400MHz-460MHz. This can be done by connecting pin 7 and 14 of HD404608H with 33Kohm register. The last modification is to connect pin 6 and pin 14 with 33Kohm register, which enables transmission on 350-460MHz, but disables receiving 118-174MHz and 800-950MHz instead. As an additional information, there is an interesting feature which let the transceiver to be a cross band repeater. This can be done by pressing UP arrow key when you turn the power on. To release this mode, do the same again. At least in Japan, these features are not documented in the manual, and Kenwood does not officially announce these, so I'm not sure whether Kenwood service center provides information on TH-77A at your place or not. -------------------------------------------------------------------- In real Life: Yutaka Muto JUNET: muto@nttcoin.ntt.jp CSNET/ARPA: muto%nttcoin.ntt.jp@relay.cs.net HAM: JH1VWP ex.VE3VWP Organization: NTT Communications and Information Prosessing Laboratories Physical mail: 1-2356 Take Yokosuka, Kanagawa 238-03 Japan The following is a simple modification for the TM-221 rig: 1- Locate the control unit board (X53-3040-XX) located behind the front panel. 2- Right below the channel select rotary switch and opposite the M.IN Sw. you will find R24 and R25.(foil side) 3- Remove R25 for 142.00 thru 151.995 Mhz RX TX 4- Move R25 to space for R24 for 138.00 thru 154.000 Mhz TX RX (Range will vary slightly from set to set) Info provided by N2EYR @ WA2SNA-1 / Eddy Salvador Note: I haven't tried this, proceed at your own risk! WA2ISE cmd: copied from packet: Msg# TSP Size #Rd Date/Time MsgID From To 1740 BF 824 0 0827/0533 4206_WA2SNA WM8J ALL@ALLBBS Sb: TM231/WEAK MIC AUDIO FIX A QUICK AND DIRTY FIX FOR THE KNWD TM231A LOW MIC OUTPUT TILL (IF) KNWD COMES OUT WITH A FIX IS TO BYPASS R 63 (3.3K). R 63 AND R64 FORM A VOLTAGE DIVIDER AT THE INPUT TO THE MIC AMP. R63 IS ON THE BOTTOM OF THE RIG. WITH THE BOTTOM COVER OFF AND THE FRONT OF THE RIG FACING YOU, LOCATE THE MIC AMP BOARD 3610 WHICH STANDS VERTICALLY OFF THE MOTHER BOARD. FOLLOW THE 3RD PIN FROM THE LEFT TO R63. A JUMPER HERE GIVES THE TX AUDIO A NICE BOOST. BE SURE TO READJUST THE DTMF OUTPUT IN THE MIC (THE ONLY POT IN THE MIC). 73 AND GOOD LUCK. GREG. 1951z, 473 msgs, #1786 last @KD6TH-4 MailBox> TM321A Mars/cap mod from WM8J msgID 2846_wa2rkn To give the TM321 tx coverage from (142 0r 143, don't remember which) to 151.995 mhz, remove the top cover. Look for a loop of wire comming from the display area (the board with the CPU) and going right back. Cutting this wire and then doing a CPU reset is all you need to do. Takes about 2 minutes. Be sure that the ends of the wire don't short to something. 73s Note: I haven't tried this, proceed at your own risk! WA2ISE Modifying the Kenwood TM-721A for Extended UHF Coverage Well I finally uncovered the specifics of the mod which will extend the UHF coverage of the TM-721A. This mod changes the UHF receive from it's factory setting of 438 - 449.995 mhz to approximately 420-460 MHZ. There are some peculiarities surrounding this mod so I'll describe them first. First of all, this mod will allow the UHF digital display to traverse from 400.000 to 499.995. The radio will not, however, tune this entire range due to a combination of a limited synthesizer lock range and the input RF amplifier bandwidth. The apparent useful tuning range is about 420-460, with sensitivity dropping off sharply at either end. Naturally, the best performance is in the middle (the Ham Band :-). Similarly, the VHF tuning range is extended in the same manner. After the mod is made, the VHF side will apparently tune from between 100-199 mhz but as stated above, there is little or no response outside of the published range (138-170 mhz), due to the same reasons as stated above. As a final side effect, note that performing this mod will remove all out-of-band transmit restrictions on the rig, for both VHF and UHF. After the mod is in place, the radio will transmit on any frequency that it can tune to. DISCLAIMER: The author of this report wishes to strongly remind those who perform this mod that it is ILLEGAL to transmit on any frequencies outside of the ham bands, EVEN IF YOU ARE OTHERWISE LICENSED TO DO SO. This is because of the radio's lack of FCC type acceptance for these frequencies. So beware! Unauthorized use of this feature could be hazardous to your ticket. MARS/CAP users are probably OK with a permit. Now for the nuts and bolts..... MODIFICATION PROCEDURE 1. Turn the radio on and write down all of your memory channel frequency assignments, PL codes and anything else you have in memory - It will all have to be reprogrammed after the mod. After writing down all of your data, turn off the unit and disconnect it from the antenna and power supply. 2. Next, remove the bottom cover on the unit. Note: this radio contains a number of CMOS parts which could be damaged by static discharge. Take all of the regular precautions to make sure that you and your tools are properly grounded for anti-static work. Note that there is a hole in the rear of the subchassis which supports the controller circuit board in which you can see a small, black, 1/4 watt resistor which is labeled on the board as R57. Using a small pair of sharp cutters, clip the lead on the end of the resistor. It is not necessary to remove the part, just clip one end and bend it slightly out of the way. 3. Next, remove the top cover and then open the front panel assembly into the service position. To do this, remove the four silver screws, one on the top, one on the bottom, and one from each side. Two of the screws are in slotted holes. Loosen the screws in the slotted holes slightly so as to allow the front panel to be pulled out and swung down in a hinge-like fashion. Once open, set the radio on a table with the hinged front panel hanging over the edge of your workbench. Familiarize yourself with the inside of this compartment. The most notable features are a silver, button type lithium battery to the left of center and a large, multi-pin microprocessor chip on the right. DO NOT DISCONNECT ANY OF THE RIBBON CABLES. 4. Locate the lithium battery and to it's left you will notice a row of five programming resistor positions, with the middle position vacant. The arrangement looks something like this: | | ____ ______ | I I:II (Bat-) |MPU | | (tery) | | | ---- ------ | | I <- R121 (remove for cross-band repeater operation) ______________________________________________ VVV front of rig VVV The (:) above indicates where a jumper is to be placed. Use care in soldering since everything is quite small. 5. Reassemble the unit in the reverse order as described above. When you power the rig up, the display should show 440.000 and 144.000 on the displays. It is now ready for operation. If necessary, perform the microprocessor reset function by holding down the F button while turning on the power. Reprogram the unit with the data you saved in step 1. Comments: There is nothing special about operating the rig once the modification is made. All functions operate exactly as before except that the range on each band is extended as described above. You will probably want to program the band scan limiting channels (A and B) on both bands since otherwise your vfo scanning will be too broad and will spend a lot of time scanning in areas which it cannot receive. In addition, there also exists a cross-band repeater mod. I do not know if having this is a prerequisite to performing the mod mentioned above. If it is, then R121 will also have to be removed. The cross- band repeater mod has already been discussed on the net so I won't go into it at this time. Enjoy this mod but don't endanger your license! Don't transmit out of band and don't allow others to, even if they're licensed for those frequencies! -------------------------------------------------------------------- | Fred Lloyd KJ6RK PP-SEL flloyd@sun.com | | Sun Microsystems, Inc. ...sun!flloyd | | Mountian View, CA | | (415) 336-6322 | | Disclaimer: If it ain't broke, don't fix it! | -------------------------------------------------------------------- ALTERNATE METHOD The procedure above did not seem to make sense to me when I looked in the unit. I used a mod I received from Km4mf, Adam, and it worked fine. In addition to pulling R58, R59, and R121, lift pins 22, 23, 24 off the board for IC3. I gives you rx/tx ability from 106.3 to 184 Mhz. and 418 to 473. Mhz. Impressed? ................et.n2ihn. TM-721A First off, I want to thank Fred Lloyd, KJ6RK, for the excellent information that he gave us on modifying the TM721-A for UHF "General Coverage" . If you have made the mods though, you have no doubt found out that the receiver just can't seem to work much above 455.650 Mhz. Not being terribly familiar with Phase Locked Loops, I feel like its out of my league to chase this one too far. But for those who are knowledgable (sp?) about those things, here is what I found. I took a Cushman FM signal generator and started walking up the band in 25 khz steps, setting the Cushman first and then tuning the 721. At 455.650 Mhz the receiver would no longer solidly receive the signal, but instead it would slowly oscillate at about a 2 cps rate between white noise and a solid full-quieting signal. My guess between playing with the radio and talking to Fred Lloyd is that the PLL circuitry is simply at the upper limit of its range. Unfortunately, almost all of the local police frequencies that I want to listen to are in the 460-462 Mhz range. I want to point out that when the receiver was tuned to 455.625 the PLL was working normally and I was able to receive a full quieting signal with a .5 microvolt signal, so we know that the problem isn't sensitivity. I suspect that there is a way to drag the VCO voltage "UP" so that you could use the "General Coverage" spectrum at the expense of the lower part of the amateur spectrum. At this point I'm going to throw the challenge back out there to you wizzards that eat and breath this digital/analog stuff to try and figure out what kind of alternatives are available to squeeze a little more out of the radios' UHF spectrum. Dave Allen KD0DE AT&T Bell Laboratories - Denver (303)538-4509 Tuning the 721 UHF for 460 megs + : Edward Thomas, N2IHN 1. FIND L4 & L3 on bottom of set, turn 4 screws CCW @ 3 turns. 2. PEAK TC1, TC2,TC3 for signal strength. 3. May need to tune TC102 for transmit output and TC101 for recv. TM-731 FREQUENCY AND CROSS BAND REPEATER MODIFICATION ===================================================== The TM-731a will transcive between 136-174 MHz and 400-500 MHz as well as perform cross band repeter function when the following modifications are performed. 1.- Remove both the top and bottom cover. Disassemble the front panel such that the control unit (X53-3250-XX) is accessable. 2.- Remove R121, R123 and R25. While R125 snd R124 must be present. 3.- If the time-out timer function is not desired, remouve R122 as well. 4.- Reassemble the unit and perform a microprocessor reset before operating the set. 5.- Preserve your license by operating within the bands it is good for. BEST 73's GERALD Note: I haven't tried or verified this, proceed at your own risk. WA2ISE Note: I could not find one of the resistors above listed in the service manual. If the above mod works out for you, or if you have done one for the 731 that works like the 721, please let me know what it is. et, n2ihn. BC200/205XLT CELLULAR RESTORATION Note: It is unlawful to monitor cellular telephone conversations. It is possible to monitor signals from the deleted ranges even without conversion. Simply add 21.7 MHz to the deleted frequency and enter the higher (image) frequency. Reception is virtually identical in strength to that which would be heard on the deleted frequency. The frequencies deleted at the factory may be restored, but the procedure must not be attempted by anyone unfamiliar with electronic circuitry. Grove Enterprises assumes no liability for damage caused by this procedure. The modification will void your warranty. TOOLS REQUIRED: Small Phillips screwdriver, small wire cutters. 1. Slide off the battery pack and remove the antenna from the scanner. 2. Using a small Phillips screwdriver, remove the two screws from the back of the scanner, the two screws which hold the battery retaining spring at the base and the spring itself. 3. Carefully pry the bottom of the rear cover from the radio and remove the cover. 4. Locate the two small screws at the base of the circuit board and remove them. Gently pull the front panel from the mainframe at the base and separate them. 5. Locate the (64 pin quad flatpack) microprocessor IC labelled "UNIDEN UC-1147" and the 10k ohm (brown-black-orange) leadless resistor positioned above the letters "DEN" on the IC. 6. Using miniature wire cutters, cut the resistor body in two without disturbing anything else near it. If the left solder pad comes loose, it may be peeled from the board. Brush or blow away any residue. This completes the restoration. REASSEMBLY 7. Insert the top of the front panel into the slot under the volume/squelch control panel and, noting carefully the alignment of the dual inline connector at the bottom of the board with the mating socket, press the front panel firmly into place. Be sure that the holes at the bottom of the circuit board line up with the holes in the plastic standoffs below them. Insert the two screws and gently tighten them. 8. Replace the back cover by inserting the top of the cover into the slot under the volume/squelch control panel; press the cover into place, insert and tighten the screws. 9. Reposition the battery retaining spring (slotted side toward notched hole), insert the two remaining screws and gently but securely tighten them. 10. Slide the battery pack into place; switch the scanner on to make sure the display comes on. If not, the battery is discharged or the dual-inline connector was misaligned during assembly (see step 7). Assuming the display comes on, press: MANUAL, 845.0, E; within two seconds, the frequency 845.000 should appear on the display. Cut this resistor | V [*10k*] [ ] I I I I I I I I I I I I I I I I I I I = = = = = = = = = U N I D E N = = = = = = = = = = U C - 1 1 4 7 = = = = = = = I I I I I I I I I I I I I I I I I I I ............................................................................... Pete Simpson, KA1AXY SIMPSON_P@MERCURY.CEO.DG.COM Data General Corp Westboro, MA 01580 (508) 870-9837 "My company doesn't have anything to do with this." ............................................................................... PRO-34 Scanner Modification In regard to the information presented (March Issue) on the handheld Radio Shack PRO-34 scanner, my own observations on the modifications have been: 1. To restore missing 800 MHz frequencies, remove D-11. 2. To add 66 to 88 MHz (European Coverage), install a diode at D-9. 3. D-10 must remain in place for full 800 MHz coverage. 4. If a diode is added at D-13 it cuts out aero band, also seems to affect 800 MHz channel spacing. 5. D-12 added dosen't seem to have any affect. 6. Only D-10 and D-11 are factory installed. RADIO SHACK 2004 EXPANDED COVERAGE: 1. Remove the 4 philips screws on the back of the unit that hold the case onto the chassis. 2. Slide the radio out of the case by pushing it out the front. Or, put another way, slide the case back, off the radio. 3. Once you've eased the radio out, turn it upside down with the front toward you. 4. Locate a board with "PC-3" stenciled on it in big white letters. It is roughly in the middle of the radio near the back. There is a rectangular, highly reflective (mirror-like) metal cover covering most of this board. 5. Gently remove this metal cover. It is held on by being press-fit over little metal dimples. A little careful prying will do the trick here. 6. Once the cover is off you should see the main CPU chip on the right, a resonator crystal (501-X I think?) in the rear right corner, and a vertical row of diodes to the left of the CPU chip. Some of diode positions will be lableled like this D-509, D-510, D-511, D-512, *D-513*, etc. I don't remember exactly which ones are labled or not, but that's not so important right now, you should get the idea. 7. The diode D-513 is labled (I know) and this is the beastie that disables the cellular phone frequencies and their 30KHz search step size. Snip this diode with diagonal cutters (or whatever). Make sure the snipped wire ends are not touching, and viola! You've got full 800MHz coverage on your Pro-2004. 8. You may want to test it at this point. (Try entering 880 MHz or some other previously disabled 800MHz frequency, and verify that you don't get an ERROR.) Re-assemble. PS: There is a TURBO-Scan mod where you can up the scan speed to around 30ch/s by replacing the resonator crystal in step 6 with a 10MHz version. Also, by soldering in a diode in what would be diode position D-510 (if it were labled) you can add 10 channels to each bank for a total of 400 ch. The problem with this is that then the keypad's labelling for channel banks becomes incorrect. You should get and verify the complete details on the mods in this "PS" because I can't supply you with complete instructions that I am 100% sure about on these. I'm just letting you know they're possible... A carrier operated light for the PRO-2004 [repost] Several PRO-2004 owners have asked for a repost of this article: A CARRIER OPERATED LIGHT FOR THE PRO-2004 SCANNER by Bob Parnass, AJ9S The July 1988 issue of Monitoring Times suggested that it may be easy to add an S-meter to the Radio ShackO PRO- 2004 scanner: "...But adding an "S" meter is even easier than previ- ously thought. Pin 10 on the IF amplifier (IC1) is an "S" meter output. With the proper bridge or meter buffer/amplifier an "S" meter is reality...." Brace yourself for disappointment - the integrated cir- cuit mentioned in the article is used for WBFM only. Despite the internal IC block diagram in the service manual, pin 10 on my PRO-2004 is useful as an S-meter output only when the radio is in the WBFM mode. Between pin 10 and ground, I placed a 10,000 ohm resistor in series with a 250 microamp meter for a simple test setup. The meter read full scale on strong signals. With no signal at all, the meter read about 70% of full scale. When the mode is set to AM or NBFM, the meter was always at zero. One could add a brie circuit here, but this metering point is of limited utility. Add a Light Instead With a room full of functioning scanners, it's difficult to determine quickly which radio is "talking." I use separate external speakers on each radio, and the spatial separation helps. In addition to "hearing" which radio is active, I like to "see" which radio is active, and carrier operated lights are effective at providing such visual cues. The idea is to illuminate a lamp when a signal opens the squelch. A small yellow light emitting diode (LED, another Bell Labs invention) is well suited to this purpose. The following modification works well on all PRO-2004 modes. To add a COR light to the PRO-2004, make use of the "scan control" pin (pin 13) on IC2, the TK10420 IC. Pin 13 has voltage present only when a signal is detected. This chip contains the IF, detector, limiter, and squelch cir- cuitry for NBFM. If you tremble with an electric drill in your hands, read no further. The LED can be mounted in a small hole drilled through the plastic front panel, just to the right of the headphone jack. Electronically, the circuit is simple. The voltage at pin 13 is not enough to drive the LED directly, so a gen- eral purpose NPN transistor (e.g., a 2N2222) can be used as a solid state switch. - Pin 13 of IC2 is connected to the transistor base through a 10,000 ohm resistor. - The emitter is grounded. - The collector is connected through a 1000 ohm resis- tor to one end of an LED. This resistor limits the LED current to about 13 milliamps. - The other end of the LED is connected to one contact on the rear of the PRO-2004's on/off, volume con- trol. This furnishes about 14 VDC unregulated circuontacire cs co ounteon afastea Modifications for the 2005 There is a socket that is not marked so it will be referred to as D501. D501 and D503 removed : Scan rate of 6/12 cps D501 only installed : Scan rate of 7/14 cps *D503 only installed : Scan rate of 8/16 cps D501 and D503 installed : Scan rate of 10/20 cps (horray!) *D502 installed : Disable 823.95-850.95 MHz and 868.95-895.95 MHz D502 removed : Full coverage from 760-1300 MHz D504 installed : Normal spacing for all bands. *D504 removed : Enable 30 kHz spacing in areas restored by D502 removal * = Stock US model configuration Modifications for the 2004 1. Remove diode from "513" to get excluded 800 MHz freqs. 2. Install a 1N914 diode in "514" to increase scan rate to 10/20 channels-per-second. 3. Install a 1N914 diode in "510" to get the extra 100 channels. 4. Remove diode from "D-44" to restore missing frequencies in th 806 to 960MHz band. 5. Remove diode from "D-45" to restore coverage from 68 to 88MHz. ------------------------------------------------------------------ In step 5 above, I have no idea what this is for. My 2004 came from the store already scanning this range, and this was the first I had ever heard of it. The same goes for step 4. When I removed D513 (as in step 1), I got those freqs back. Perhaps the user who originally posted these had a radio from a different production run. All I can "vouch" for is steps 1, 2, and 3. THE RADIO SHACK PRO-2005 PROGRAMMABLE SCANNER by Bob Parnass, AJ9S Manufactured in Japan by General Research Electronics, the Radio Shack PRO-2005 is a 400 channel, wide coverage scanner radio, incorporating NBFM, WBFM, and AM modes. It is the successor to the PRO-2004, the super scanner which put Radio Shack out in front of its competition in the base station scanner market. The 2005 is basically a 400 channel PRO-2004, built using surface mount components, and housed in a smaller pack- age. Frequency Coverage Radio Shack's last minute decision to remove cellular telephone frequency coverage from the PRO-2004 caused a 7 week delay in its introduction. The PRO-2005 appeared in the stores promptly on the heels of the 2004 closeout sale. Both the PRO-2004 and PRO-2005 cover 25-520 and 760-1300 MHz, except for 2 gaps in the cellular telephone bands. The two gaps in the 800 MHz range can be restored in either scanner by clipping a diode. A matrix of diodes, attached to the microprocessor's input port, is often used to configure radios for sale in different markets. The diode matrix on new the PRO-2005 is located on the vertical circuit board just behind the front panel. There are 2 diodes present, and holes drilled for 2 more. Lots of Memory The PRO-2005 has the usual features that scanner buffs have come to expect: individual channel lockouts, selectable rescan delay, an external speaker jack, etc. But, the 400 channel capacity of the PRO-2005 sets another an industry record, just as the 300 channel PRO- 2004 did! Casual scanner users may scoff at the useful- ness of having so many channels, but seasoned monitorists can have those channels filled up in no time flat, espe- cially with frequencies in the vast 225-400 MHz military air band, and other federal government allocations. With so many channels to program, one dreads the thought of a power failure, which could clear memory in a hurry. Not to worry, the PRO-2005 memory is backed up by a - 2 - conventional 9 volt alkaline battery (not supplied). The 400 channels are divided into 10 banks of 40 channels each, and one can select or deselect any channel bank from the scan list. Individual channels can be locked out in the customary way, but the PRO-2005 maintains the handy feature introduced in the PRO-2004, a LOCKOUT REVIEW. Successive depressions of this key step through the locked out channels. Scanners worth their keep have a priority feature, with channel 1 usually designated the priority channel. The PRO-2005 is more flexible; any of the 400 channels may be designated the priority channel. When the PRIORITY key is depressed, that channel will be sampled every 2 seconds, and the radio will stay there if a signal is heard. The PRO-2005 has two scan speeds, approximately 8 and 16 channels/second, although one would probably use the fas- ter speed in most instances. This is the same speed as the stock PRO-2004, as measured by your reviewer. A diode could be added to the PRO-2004 diode matrix to speed up the scan and search rates by 25%. The provision for extra diodes in the diode matrix makes one hopeful that the same speedup trick can be applied to the newer PRO-2005. When programming a channel, the PRO-2005 firmware sets the mode automatically, based on its idea of what mode is most prevalent on that frequency. This feature saves extra keystrokes, and makes one appreciate the thought that went into the design of this radio. The default mode can be overridden easily, if need be, like to listen to a NBFM satellite in the 225-400 MHz range, which is mainly populated with AM signals. Searching The SEARCH facility found on most programmable scanners allows the entry of a pair of frequencies, then by press- ing a key, the radio searches frequencies between those limits. The PRO-2005 allows for 10 pairs of limits! These pairs of limits are stored in their own memory, and don't use up any of the conventional 400 memory channels. One can set up several search pairs, for instance: - 46.610-46.970 MHz: cordless telephones - 144-148 MHz: the 2 meter ham band - 3 - - 30.01-30.56, 32-33, 36-37 MHz: US Govt Another unique feature is the MONITOR key, which stops the search and stores the frequency in one of ten special monitor memories. These memories are separate from the 400 main memory channels. The search can be restarted from where it left off by striking the up or down arrow key. The user can select the search direction (up or down), and step size of 5, 12.5, or 50 kHz, although the PRO- 2005 is intelligent enough to select a default step size based on the frequencies being searched. As on the PRO- 2004, there is a hidden step size of 30 kHz, but apparently this step size was disabled when the cellular telephone frequency coverage was removed. The selected parameters are displayed on the LCD panel, smaller than the panel in the PRO-2004. Search speed is switchable between slow and fast, with fast search being about 14 increments/second (versus 12 for the Uniden/Bearcat 800XLT). For a 12.5 kHz increment, this translates to 11.2 MHz/minute (versus 9.6 MHz/minute for the 800XLT). The DIRECT key allows one to start searching up or down from whatever frequency is on the display. Let's say the scanner is in MANUAL mode, and set at channel 26, which contains 460.100 MHz. Striking the DIRECT then UP-ARROW keys starts the PRO-2005 searching upwards from 460.100. This is a nice feature. The PRO-2005 contains a "window detector" circuit, which is called into play during a SEARCH operation. This cir- cuit tries to detect when the radio is tuned close to the center frequency of a station, and prevents the search from halting prematurely, off to the side of the signal. The AFC (automatic frequency control) circuit of the Bearcat 800XLT often causes a search of 850 MHz signals to halt prematurely. Even though the signal sounds on frequency, the display reads the wrong frequency. Nei- ther the PRO-2004 nor the PRO-2005 have this problem. The PRO-2005 includes a SOUND SQUELCH, resembling the VSC circuit on the Icom R-7000, which may be used during scan or search operations. With the the sound squelch enabled, signified by a red lamp above the pushbutton, the scanner will skip over unmodulated signals. This is handy for skipping over "birdies", or link signals with a constant carrier. - 4 - The manual warns that the sound squelch may be fooled by signals with low modulation, and skip over them. The PRO-2005 SOUND SQUELCH tries to detect the presence or absence of modulation (not human speech), so unfor- tunately, it thinks that noisy dead carriers, digital data signals, and paging tones are worth monitoring and will stop the scanner to listen to them. Taping Facility A tape recorder can be connected to the TAPE phono jack on the rear panel, which provides 600 mV of audio at a 10,000 ohm impedance. An audio filtering circuit rolls off the high frequency components before they reach the TAPE jack, which makes it impossible to use it for pick- ing off FM subcarrier signals. In addition to a rear mounted external speaker jack, there is a miniature head- phone jack on the front of the scanner. The PRO-2005 lacks a COR (carrier operated relay) output, like ICOM R7000 and older Bearcat 300 have, which would be useful for actuating a tape recorder. Basic Performance To evaluate sensitivity, the PRO-2005 was compared with it's father, the PRO-2004. Since a signal generator was not used, quantitative measurements could not be made. Instead, an Antenna Specialists AV-801 antenna was switched between radios, signals from stations were com- pared by ear, and the results tabulated. Simply put, the PRO-2005 proved moderately more sensitive than the PRO-2004 on most bands tested, and just slightly more sensitive on a few bands. The cost one pays for the 2005's increased sensitivity is having to put up with hearing 800 MHz trunked systems and cellular telephone conversations while searching the 118 - 132 MHz commer- cial aircraft band. The 800 MHz interference was heard only on the 2005, not the 2004. Other than that, inter- modulation interference from paging affected both scanners to the same degree, and on the same frequencies. Although both the 2004 and 2005 can suffer the effects of intermod, they are much more immune than the overly sen- sitive, image laden Bearcat 800XLT. The PRO-2005 has a 10 dB attenuator, operable by a slide switch on the rear. - 5 - The up conversion design of both the ICOM R-7000 and Radio Shack PRO-2005 allows use of a very high IF (inter- mediate frequency), which helps avoid image problems. The PRO-2004 owner's manual contains a frequency alloca- tion chart and a section on images. This section appears in the manuals for other Radio Shack models, and was thoughtlessly thrown into the 2005 manual. It babbles on about images being 21.4 MHz away from the real frequency -- true for simpler models, but not so for the PRO-2005. The audio output quality is good, although the top mounted speaker directs the sound at the ceiling, but adding an external speaker would allow the sound to be directed at the user. Unfortunately, the audio level of AM signals is somewhat below that of NBFM signals, requiring a different setting of the volume control. When scanning both AM and NBFM modes, one has to find a compromise position of the volume control. The PRO-2005 squelch control has a wee bit too much hys- teresis, a trait inherited from its ancestors. It's like having too much play in a car's steering wheel, or back- lash in a gear set. This hysteresis forces one to keep the squelch at a tighter setting, missing weaker signals when scanning or searching. It's not as sloppy as in the early PRO-2004s. I've successfully eliminated this prob- lem completely by replacing a single resistor on the 800XLT, as well as the PRO-2002, PRO-2003, PRO-2004 and PRO-24 scanners. Mechanical Construction The PRO-2005 is lighter than the 2004. It is enclosed in a gray plastic cabinet, with a plastic front panel. If one is going to pay $420, one deserves to own some metal, but several stages are internally shielded in their own metal compartments. The entirely plastic cabinet of the older PRO2003 allowed wideband noise to radiate out of the scanner and into nearby shortwave receivers. The PRO-2005 vertical front panel is an advancement over the sloping panel of the 2004. Now you can stack the scanner on top of other equipment and see the controls without standing up. If sitting directly on a table, two hinged plastic feet, padded with rubber bumpers, can fold out from under the front of the radio to tilt it at a good viewing angle. - 6 - There is a single BNC antenna connector on the rear of the PRO-2005, and a single telescoping antenna is sup- plied. Internal construction is excellent, and the internal shielding is commendable. Interstage shielding is very important in a wide band receiver, to prevent it from "hearing itself", an undesirable phenomena which results in birdies. The PRO-2005 owner's manual lists the birdie frequencies. The shielding is much better in the PRO- 2005 than in the 800XLT, which uses no shielding around the 800 MHz converter stage, and probably accounts for some of the birdies in the Bearcat. Frequencies and other indicators are displayed on a back- lit LCD (liquid crystal display) panel, and the level of backlighting can be dimmed by a pushbutton switch. Vision impaired scanner buffs will appreciate the conven- tional raised rubber keyboard in the PRO-2005, which replaced the flat membrane keyboard in the PRO-2004. Only moderate pressure is required for actuation, and key depressions are confirmed by a mild "beep" audio tone. The PRO-2005 is the right size to fit under the dashboard of intermediate sized cars. Although it can be operated on 12 VDC, neither a mobile power cord nor mounting bracket are provided. These items were included with earlier, pre-PRO-2004 Radio Shack models. The AC power cord is not detachable, and would have to be bundled up to keep it out of the way in a mobile installation. Owner's Manual The user manual is outstanding compared with the fold out sheet furnished with Uniden scanner. A single page frequency allocations chart is included, but is not current. There is no schematic. Thankfully, detailed service manuals for Radio Shack scanners are usually available for $7.50 or $10.00. The PRO-2005 is warranted for 1 year, which is reassur- ing. What's Missing? So with all these neat features, what's missing from the PRO-2005? A "search and store" mode, like that on the - 7 - ICOM R7000 and older Bearcat 250 would have been nice. A lighted keyboard and a signal strength meter would also be welcome, as would a mobile mounting bracket and SCA output jack. Summary If all one wants is a scanner to monitor local police and fire, there are certainly cheaper and simpler models than the PRO-2005. This scanner is for those who enjoy actively exploring voice communications in the VHF/UHF spectrum. If you already own a PRO-2004 and have added the diode to expand it to 400 channels, there is little to be gained by purchasing a new PRO-2005 -- unless, of course, you are a passionate scanner collector. The PRO-2005 has the right features and performance, especially for scanning the wide 225-400 MHz military aircraft band. Good design should not to be taken for granted. GRE engineers used the power of the micropro- cessor to implement useful features in the PRO-2005. Similar processing horsepower was not used so wisely in the Yaesu FRG-9600. At about $420, the PRO-2005 provides a good alternative to those not wishing to spend $1050 for an ICOM R7000. That's all, so far! If you get any more, let me know...........et. -- IIIIIIIIIIIIIIIIIIIIIII HHHHH HHHHH NNNNNNNNNN NNNNN IIIII HHHHHHHHHHHHHHHHHHHHHHHH NNNNN NNNNNN NNNNN IIIIIIIIIIIIIIIIIIIIIII HHHHH HHHHH NNNNN NNNNNNNNNN Edward Thomas, N2IHN, POB. 3233 Long Branch, NJ. 07740 n2ihn@ka2qhd.UUCP