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- Newsgroups: rec.radio.amateur.misc
- From: jreese@NeoSoft.com (Jim Reese)
- Subject: MICOR VHF mobile to repeater converstion instructions (long!)
- Organization: NeoSoft Communications Services -- (713) 684-5900
- Distribution: usa
- Date: Thu, 5 Nov 1992 22:10:26 GMT
- Message-ID: <Bx9K9I.I8s@NeoSoft.com>
- Summary: step by step instructions to convert micor VHF mobile to repeater
- Lines: 163
-
- Questions regarding this should be directed to jreese@sugar.neosoft.com
-
- There are associated diagrams mentioned in the text. If you are unable to
- figure out what's going on without the diagrams, mail me and I'll try to
- get the diagrams to you some way.
-
- Jim Reese
- WD5IYT
-
- Instructions for Conversion of Motorola VHF Micor to Repeater Service
-
-
- This modification is not for the faint-hearted. Be sure you are very
- comfortable with the operation of the MICOR radio before you attempt this
- modification. A thorough understanding of the way the MICOR radio and control
- system works is absolutely essential for the success of this conversion.
-
-
- Modification Notes
-
- This modification was developed for radios having receiver RF/IF board series
- TLD8270A; audio/squelch models TLN4310A-2 thru TLN4310A-5; and exciter models
- TLD8261A, TLD8262A, TLD8261B, or TLD8262B. If your radio differs from these
- part numbers, all or part of this modification may be different from the
- descriptions. Use your judgement to alter these instructions as necessary.
-
- Whenever "Molex Pin x" is mentioned, it refers to the Armadillo Standard
- connector. This is a small, 9 pin Molex connector which serves as the
- interface for all of the Armadillo radios. Use a Female connector on the
- radio end. The standard pinout of the connector is:
-
- 1 - Ground
- 2 - Receive Audio Output
- 3 - n/c
- 4 - Transmit Audio Input
- 5 - COS Output
- 6 - PTT Input
- 7 - n/c
- 8 - PL Decoder Output (Sense)
- 9 - PL Select Input
-
- The COS output and PTT input are open-collector to ground signals. Pin 8 goes
- to +9.6 V when PL is decoded. Pin 9 is ground for PL, open for Carrier.
-
- These modifications allow "PL and Squelch" operation. This means that when in
- PL, the normal squelch circuit still operates. This avoids long noise bursts
- upon unkeying.
-
- If using an Advanced Computer Controls, S-Com or other commercial controller
- which requires an active high PL sense signal, the signal at pin 8 can be
- attached to the "PL Sense input" on the controller . It will drive this input
- directly. On the S-Com controller, the pull up resistor on the PL sense input
- must be removed for proper operation.
-
-
- List of Tables and Illustrations
-
- There are several illustrations which are detailed below. Refer to them as
- needed when modifying or constructing pieces of this project.
-
- Table 1: This is a complete hookup chart for the control head plug and
- interface board.
-
- Figure 1: Schematic of control head plug, with simple diagram.
- Figure 2: Board Layout of audio squelch board detailing added capacitors.
- Figure 3: Schematic of interface board.
- Figure 4: Rough layout of interface board.
-
-
- Useful Motorola Part Numbers
-
-
- 68-81008E40-D Manual for VHF MICOR
- K1007A TX Channel Element for VHF MICOR
- K1005A RX Channel Element for VHF MICOR
- KLN-6210A PL Encode Reed
- TLN-8381A PL Decode Reed
- 01-84307A89 Empty Control Head Plug less cable, complete with pins
- 66-84690C01 Contact Removal Tool for MICOR plugs
- TKN-6458A Large Fuse Holder for Primary Power (40A)
-
-
- Step-By-Step Instructions for Modification
-
-
- Step 1: Make sure that the radio operates properly BEFORE any modifications
- are done. If there are problems with the radio, they will be easier to fix
- before the mods are done.
-
- Step 2: If you are satisfied with the operation of the radio, construct the
- control head plug per figure 1 and table 1. Use miniature pots and switches
- inside the control head plug. It is rather tight inside, so be careful to
- check that the connector will re-assemble before you drill it up. After you
- have constructed the connector, make the following connections inside the
- control head plug: Jump control head pins 3, 8, and 22 to +12 V. Jump pins 9,
- 11, and 17 to ground. Plug the newly constructed control head plug into the
- radio and verify proper operation with the new control arrangement. If there
- are problems here, troubleshoot them NOW. Do not wait until later, as you may
- be chasing more than one problem.
-
- Step 3: There are some modifications required on the control board and the
- receiver audio/squelch board in order to make the radio full duplex and to
- make preparations for the interface board. Remove CR201 on the audio/squelch
- board. Then, jump the F1 channel element to ground as described in the
- Motorola manual. Next, jump pins 1 and 4 of the audio squelch board. On the
- later version audio squelch board, there is a place for a jumper (JU-202), on
- earlier units, just make the jump with wire wrap wire. Next, remove a jumper
- on the audio squelch board which goes from pin 3 of the PL decoder to IC-202
- pin 8. This is near the pins which the PL board plugs into. Check for
- continuity from pin 3 of the PL decoder to pin 11 of the audio squelch board
- with an ohmmeter. If there is not continuity, add a jumper. The later boards
- have a trace from pin 3 of PL to pin 11 of audio squelch, on earlier boards,
- pin 11 is unused, and you should jump from PL decoder 3 to audio squelch 11
- with some wire wrap wire. Add 15pF capacitors between the following pins on
- the two chips on the audio squelch board. Figure 2 details the location of
- these caps. On IC-201, add a cap between pin 3 and 4, and between pin 3 and
- 5. On IC-202, add caps between 5 and 9, 5 and 13, and two caps between 5 and
- 15. This makes the board less susceptible to RF.
-
- Step 4: Next, carefully remove the front casting from the chassis. This is
- done by removing the four screws top and bottom as well as two screws on the
- control head plug. This is kind of tricky, so be careful to remember how you
- got it apart so you can re-assemble it later. You will expose the antenna
- relay with its two associated coax cables running to the transmitter and
- receiver. Unplug the receive coax from the antenna relay.
-
-
- Step 5: Procure a BNC chassis mount connector for a receive antenna jack.
- Mount this connector on the top side curved surface of the front casting on
- the side opposite from where the lock is located. Be very careful to locate
- this connector so that it does not hinder the operation of the latch
- mechanism. Attach the receive coax to this connector routing the cable
- through a hole which you will drill in the front of the radio chassis. The
- method will be obvious once you have examined the unit with the front casting
- removed.
-
-
- Step 6: Construct the interface board using the schematic and board layout in
- the packet. Install this board on the three unused mounting tabs near the
- rear center of the radio. These tabs are above the control board. Wire the
- board up as described in table 1. At this point, the radio will be operating
- full duplex, and you should be able to put the radio in PL by flipping the
- switch on the control head plug to the PL position. Verify that you have +9.6
- volts at the 9 pin molex connector PL SENSE pin when the correct PL code is
- being sent. Also verify correct receive audio gating and COS action.
-
-
- Tune Up Instructions
-
- Tune the transmitter and receiver per the Motorola manual. Follow the
- procedures exactly.
-
- Adjust the power set for the desired power output. I reccommend no more than
- 60 Watts for 110 Watt radios, 40 Watts for 60 Watt Radios, and 30 Watts for 45
- Watt Radios.
-
- That's it. you are now ready for major repeating action. Make sure that you
- have adequate forced air cooling on the PA at all times during operation. The
- Micor PA is not easy to fix, and when it blows, it blows big.
- --
- Jim Reese, WD5IYT | "Real Texans never refer to trouble
- jreese@sugar.neosoft.com | as deep doo-doo" --Molly Ivins
-
-
-
-