Date: Sun, 15 May 94 04:30:29 PDT From: Ham-Space Mailing List and Newsgroup Errors-To: Ham-Space-Errors@UCSD.Edu Reply-To: Ham-Space@UCSD.Edu Precedence: Bulk Subject: Ham-Space Digest V94 #124 To: Ham-Space Ham-Space Digest Sun, 15 May 94 Volume 94 : Issue 124 Today's Topics: 435 MHZ down converters? (2 msgs) 80ns EPROM - 27C512 and Trakbox ORBS$133.OSCAR.AMSAT Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Space Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-space". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: Thu, 12 May 1994 21:43:22 GMT From: ihnp4.ucsd.edu!newshub.sdsu.edu!nic-nac.CSU.net!usc!howland.reston.ans.net!europa.eng.gtefsd.com!gatech!darwin.sura.net!fconvx.ncifcrf.gov!mack@network.ucsd.edu Subject: 435 MHZ down converters? To: ham-space@ucsd.edu In article <2qrk5q$2tb@search01.news.aol.com> wa4ymz@aol.com (Wa4ymz) writes: >I'm just about set up for the packet sats with just one exception: I don't have >a receive setup. I'm planning to use a TS-670, or possibly a TS-690, HF rig >as an IF, but I'll be needing a down converter. Since the satellites seem to >down-link on 435.xxx through 437.xxx MHz, I'll need one that will allow >switching segments or have a 6M output. I use a hamtronics which comes out at 28MHz, I have the 432 version but its available in a 435 version. I'm quite happy with it, but according to the poop I read here, it isn't the greatest thing around. For $100 it's at least OK, at the circuit board is nicely done for what that's worth. >I have a mast-mount pre-amp at 70cM, >but would like to mount the converter at the antenna to minimize coax signal >loss. Is this a big concern if I use the pre-amp? Not at all. If you have a 20db gain preamp, then you can afford to have maybe 15db of loss in the coax before you get into trouble. You can use RG-58 on the way down :-). I have the converter next to the HF receiver. Note that sending power up the same line as the receive comes down leaves you open to the one time when the relays don't change over just right and you blow the preamp. Then you have to go get it off the tower etc. A real pain. I've spent the extra money for some cheap coax for the receive line and have one relay in the system at the antenna. If the relay doesn't change in time for some reason,(and this will happen eventually), then your transmitter faces an open circuit and the ALC shuts it down and the preamp is safe. Joe Mack NA3T mack@ncifcrf.gov >I'd certainly appreciate >suggestions and/or observations of the set-up anyone might be using. PS, can't >really afford a full blown xcvr for the band at this time unless someone has >something for sale or can point me in the right direction. Thanks. > >Gary WA4YMZ ------------------------------ Date: Sat, 14 May 1994 23:37:06 GMT From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!wupost!waikato!comp.vuw.ac.nz!frc!wk@network.ucsd.edu Subject: 435 MHZ down converters? To: ham-space@ucsd.edu The 70 cm -> 10 m down converter is the approach I have taken to get on the microstats. It helps if your HF rig has a general coverage receiver, as you'll need 3 MHz of IF to cover the 70 cm sat band. I have converted 435 MHz to 27 MHz (finally a use for that band :-) and 438 ends up at 30 MHz. The 408 MHz crystal train is out of a German book (UHF Unterlage), driving an SBL1 diode ring mixer. The ARRL handbook has some good hints on how to terminate the SBL1 properly. Another book worth looking at for down converter design is the VHF/UHF DX handbook, published by the RSGB if I am not wrong, this book has excellent design tips on transverters and RF power amps. You could move your preamp to the mast head, or even the entire converter. The choice depends on your transmission (rx?) line losses. If losses are high, you should consider putting the entire converter up, to allow you to minimize front end gain and improve intermod performance. Moderate losses, and you could put up with the less than ideal gain distribution and use a masthead preamp only. In case of a short run of good quality coax, you could decide to trade a little bit of performance for the convenience of having preamp and converter in the shack. If you are using a beam to track the micro sats, things become much less critical, an omni downlink antenna places much higher demands on noise figure, sensitivity and intermod resistance. Basically, there are no hard and fast rules: 'it depends'. Using a GP and 15 m of RG58 (all electronics in the shack) I receive the microsats around S5 during good passes. I get them from 20 deg elevation, but as expected fading gets pretty bad when the rise high. Signals aren't really good enough, the TAPR PSK modem has trouble AFC tracking at times. I am working on a Lindenblad which will have a 3SK97 masthead preamp and RG213 coax. Wilbert ZL2BSJ -- Wilbert Knol, Acoustics Group, MAF Marine Research, Wellington, New Zealand. Usenet: wk@frc.maf.govt.nz PACKET:ZL2BSJ@ZL2WA.NZL.OC AMPR:[44.147.180.88] AX25 NET/ROM TCP/IP MBX 146.625 147.075 MHz 24 hrs. ------------------------------ Date: Fri, 13 May 1994 16:03:33 GMT From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!torn!news.unb.ca!upei.ca!UPEI.CA!seeler@network.ucsd.edu Subject: 80ns EPROM - 27C512 and Trakbox To: ham-space@ucsd.edu Has anyone been successful in finding 80 ns access 27C512 EPROMS for the trakbox upgrade? Canadian companies do not currently carry this item in stock - nor are they willing to part with just 1 - 3 units :-) The name and phone number ( non 800 #s pls) or location of American suppliers would be greatly appreciated! Thanks in advance DAve Seeler, VY2DCS Internet: Seeler@upei.ca ps - a manufacturer is Advanced Microdevices ( AM27C512-75 DC) for example. ------------------------------ Date: Fri, 13 May 1994 07:56:00 MDT From: ihnp4.ucsd.edu!news.acns.nwu.edu!math.ohio-state.edu!howland.reston.ans.net!gatech!newsxfer.itd.umich.edu!nntp.cs.ubc.ca!alberta!ve6mgs!usenet@network.ucsd.edu Subject: ORBS$133.OSCAR.AMSAT To: ham-space@ucsd.edu SB KEPS @ AMSAT $ORBS-133.O Orbital Elements 133.OSCAR HR AMSAT ORBITAL ELEMENTS FOR OSCAR SATELLITES FROM WA5QGD FORT WORTH,TX May 13, 1994 BID: $ORBS-133.O TO ALL RADIO AMATEURS BT Satellite: AO-10 Catalog number: 14129 Epoch time: 94130.80459721 Element set: 277 Inclination: 27.1382 deg RA of node: 328.2037 deg Eccentricity: 0.6020986 Arg of perigee: 177.1779 deg Mean anomaly: 188.9849 deg Mean motion: 2.05880044 rev/day Decay rate: -1.6e-07 rev/day^2 Epoch rev: 8201 Checksum: 313 Satellite: UO-11 Catalog number: 14781 Epoch time: 94129.54582830 Element set: 687 Inclination: 97.7882 deg RA of node: 146.0792 deg Eccentricity: 0.0012814 Arg of perigee: 37.7565 deg Mean anomaly: 322.4528 deg Mean motion: 14.69203696 rev/day Decay rate: 2.11e-06 rev/day^2 Epoch rev: 54463 Checksum: 331 Satellite: RS-10/11 Catalog number: 18129 Epoch time: 94130.08415553 Element set: 896 Inclination: 82.9265 deg RA of node: 357.0128 deg Eccentricity: 0.0012666 Arg of perigee: 123.6132 deg Mean anomaly: 236.6238 deg Mean motion: 13.72335938 rev/day Decay rate: -.00000000 rev/day^2 Epoch rev: 34468 Checksum: 295 Satellite: AO-13 Catalog number: 19216 Epoch time: 94126.28995779 Element set: 909 Inclination: 57.8344 deg RA of node: 254.1456 deg Eccentricity: 0.7210927 Arg of perigee: 340.7734 deg Mean anomaly: 2.0051 deg Mean motion: 2.09721388 rev/day Decay rate: -3.21e-06 rev/day^2 Epoch rev: 4513 Checksum: 311 Satellite: FO-20 Catalog number: 20480 Epoch time: 94129.46561045 Element set: 682 Inclination: 99.0315 deg RA of node: 288.6150 deg Eccentricity: 0.0541341 Arg of perigee: 67.1736 deg Mean anomaly: 298.5600 deg Mean motion: 12.83225679 rev/day Decay rate: -8.0e-08 rev/day^2 Epoch rev: 19916 Checksum: 315 Satellite: AO-21 Catalog number: 21087 Epoch time: 94129.16206480 Element set: 462 Inclination: 82.9448 deg RA of node: 171.5920 deg Eccentricity: 0.0034734 Arg of perigee: 189.9860 deg Mean anomaly: 170.0610 deg Mean motion: 13.74538981 rev/day Decay rate: 9.4e-07 rev/day^2 Epoch rev: 16422 Checksum: 310 Satellite: RS-12/13 Catalog number: 21089 Epoch time: 94129.20675370 Element set: 685 Inclination: 82.9235 deg RA of node: 40.3573 deg Eccentricity: 0.0027928 Arg of perigee: 215.5272 deg Mean anomaly: 144.4021 deg Mean motion: 13.74040261 rev/day Decay rate: 5.0e-07 rev/day^2 Epoch rev: 16329 Checksum: 285 Satellite: ARSENE Catalog number: 22654 Epoch time: 94124.94294243 Element set: 251 Inclination: 1.7729 deg RA of node: 101.4452 deg Eccentricity: 0.2921942 Arg of perigee: 180.0752 deg Mean anomaly: 180.1868 deg Mean motion: 1.42202361 rev/day Decay rate: -1.20e-06 rev/day^2 Epoch rev: 58 Checksum: 258 /EX ------------------------------ End of Ham-Space Digest V94 #124 ******************************