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info wanted on old mobile unit




 
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Patrick J. / KD5OEI
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« on: September 24, 2017, 01:22:51 AM »

Result of 80 Yr old guy cleaning out his sheds.

This thing is FM but is so obscure apparently I have to ask everywhere. Anyone have info on this?
It's a gray box about 6x7 and 14" long. I was asked to see if it can be made to work.

Communications Co. Inc (Comco) 900T/D
60s vintage?
VHF FM transceiver 144-174MHz
RX: semiconductor
TX: semicondctor, with vacuum tube driver and PA
single channel, oven crystalled for 151.925MHz
separate RX and TX frequency selection /tuning
onboard inverter for B+, 4 pcs. C441 PNP GE transistor, TO-36
7551 driver, 6883 PA
Remote head
Internal test panel with mic and TR sw, test points
I don't have a pic. yet, maybe tomorrow.

---------------------

These others followed same person home:

Stoner Electronics SSB-100 (2 pcs.)
HF SSB/AM transceiver
RX: semiconductor
TX: vacuum tube
2) 2N1073 B+ inverter
2) 2N301 PP audio output
2)8042 RF PA, 7905 driver (8042 is 1 second instant-heat type)
4 crystal controlled channels /tuned presets
separate RX and TX frequency selection /tuning
promising.. maybe?

RF Communications RF-403
VHF-FM  transceiver
2-CH crystal controlled
says T 148.010, T 143.99, R 143.99
separate RX and TX frequency selection /tuning
onboard inverter for B+, TO-3 cased 2 pcs.
RX: semiconductor
TX: semicondctor, with vacuum tube PA
PA: amperex style dual tetrode, push pull, heatsinked to rear panel




* stoner_ssb-100.gif (134.81 KB, 614x260 - viewed 78 times.)

* VHF-FM-Radio-Telephone-RF-403-Marine-Aircraft-Transceiver.jpg (107.59 KB, 800x600 - viewed 62 times.)
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #1 on: September 24, 2017, 01:37:43 AM »

I used to have a manual for the RF-403.  Long gone now.  It was a good radio.  I put four of them on 154.250 for our volunteer fire department west of Ft. Lauderdale.  Three in fire trucks, one in the chief's vehicle, we used them from 1973 to 1977.  They were solid and very reliable. 
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« Reply #2 on: September 24, 2017, 08:53:43 AM »

I also have two of the Stoner SSB-100 units. They only have the USB filter installed, empty space for the LSB. Haven't yet found any manuals.
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Patrick J. / KD5OEI
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« Reply #3 on: September 24, 2017, 11:43:04 PM »

I really like the instant-on filaments in the Stoner SSB-100 finals. Those old stuff is amazing. How did people live with 4 frequencies? A different era in time.

Do you know what frequency range it will cover? Right about the manual. I know it is designed for a regular tech to change frequencies easily in the shop but I doubt I would mess with it unless I had the book, not knowing what all the coils are for. Also changing bands in the PA compartment involves a tapped toroid, so which taps?

I could see using the RF-403 for simplex or for a single repeater but in my area there are too many choices.

A fiend wants the Comco 900 - said something about it converting to nice little modulator but I don't see that. ?

For any of them, buying crystals would not be cost effective.
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« Reply #4 on: September 24, 2017, 11:52:41 PM »

here's that beautiful 8042 tube data. Fairly linear curves for a beam tube

BTW you can get your own JEDEC tube data DVDs from the TCA Tube Collectors Associate. These have all the official data sheets as submitted to JEDEC by the tube manufacturers. I recommend joining and/or buying this product. http://www.tubecollectors.org/index.htm You may have to contact one of the guys there, I don't see the link right now.

"TCA JEDEC DATA TREASURE
August 2010 Indexes to JEDEC files copyright © 2010 James P. Cross.
   The enclosed DVD-ROM contains a "treasure" of information on about 7300 "registration release" records from the Joint Electron Devices Engineering council of the Electronic Industries Association covering data on a much larger number of tubes and semiconductors."

* type 8042.pdf (192.76 KB - downloaded 13 times.)
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« Reply #5 on: September 25, 2017, 02:07:32 AM »

The Comco unit is one of their very last products.  Comco was in Coral Gables, Florida and went out of business about 1972.  If I recall correctly that model had some of the receiver circuitry inside the control head.  Comco seems to have survived off of government contracts as they had many of them, from the early days of WWII to the end of the Vietnam involvement.  Their 1950's and 60's mobile radios all had the power supply built inside the control head and the high voltage cabled to the radio drawer in the vehicle trunk.

Comco manuals can be exceedingly difficult to come by but they do show up on eBay.

The Comco portable radios of the late 60's to the end were relabeled products of Tekk, also labeled Repco, DuMont, Aerotron, Federal Sign and Signal, and others.

Where did you plan on getting crystals?  There is no manufacturer of crystals left in the USA that will produce custom crystals in small quantity.  When there was, as of a few months ago, you would be looking at $ 75 for a set of crystals to do one channel.  You can buy a Baofeng dual bander handheld for less than that.  This situation has made these types of radios mainly just collectors' items.

The 8042 and 7905 are dark heater instant heating tubes.  The 8042 is the same as a 6146 otherwise and the 7905 is like a 6360 or 12BY7.  The 7905 is also used in the AN/PRC-47 HF radio.   

The marine SSB radios are surprisingly difficult to get manuals for, regardless of manufacturer.  For those, the W9RAN programmable oscillator boards will solve the crystal issue, and 60 Meters is a good band to park them on.

I think I have seen the Harris manual on eBay.  The military used these a lot and they were surplused out to the MARS program about 1972 more or less.  I had trouble with dip tantalum capacitors going dead short on them but otherwise they were reliable and robust, although ugly.
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Geoff Fors
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« Reply #6 on: September 28, 2017, 09:14:17 AM »

Back in the late seventies there were a bunch of RF-403 radios that were released thru MARS, at the time my understanding was they were used as VHF FM radios on PBR and the like in Vietnam. Replaced the tube amplifier and power supply with little ten watt solid state amplifiers in a couple that we refitted for Ham use. 143.99/148.01 was the frequency of the CAP repeater that we had on base at that time and remember setting up several handhelds for operation on that split. Think the manual had a picture of a sixteen channel version of the radio on the cover but itís been a long time and may be mistaken. From what I remember that radio was mysteriously very GE Master looking. Back in those days I had my tech license and we only had CW privileges on HF so spent all my time up on VHF FM running radios like the Motorola Motrack, Micor and GE radios like the Master and occasionally huge old Progress line and RCA Super Carphone sets. Lots of ordering of crystals and dreamed of the day when I would not be ďrock boundĒ. Sometimes sit around and think about those old Progress and other Motorola base stations and there huge full size cabinets, meters and how they were designed to be maintained and kept in operation forever and think about hoe it would be fun to have an old repeater or high power base around just to look at but you know how floor space becomes a premium. When they allowed us old five word per minute techs to become generals thatís when I started to migrate to AM stuff and SSB and have been there for some time now but in some ways those huge high powered VHF and UHF business band base stations were something like the heavy metal AM stuff in that you can have something thatís huge and easy to work on.


* oldrack.jpg (11.49 KB, 250x313 - viewed 60 times.)
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« Reply #7 on: September 30, 2017, 01:36:02 AM »

I really don't know what to do with these things. I doubt I will be buying crystals and I don't use VHF much. They are not really worth too much, except to look at. A home might be found for the SSB units as a friend ran into a collector of Stoner products. The Comco - there may be a panel with a speaker and stuff with it. If anyone wants the VHF stuff please PM.. it will otherwise probably just languish on a shelf on the corner.


If I recall, the front ends on the old VHF stuff was pretty narrow. Not sure if a synthesized VFO covering 2M would work, and there's the final as well, not sure that it's wide enough to cover 2M without retuning.

Seeing the huge rack VHF radio there, I have the same three top modules, remounted into a compact rackmount chassis. Someone did a real nice job on it, and it works, although on one frequency 146.700. I kept it because of the nice job done on it. Picture here: http://bunkerofdoom.com/cap/fix1/01.JPG

I saved a high power FM base from a guy that wanted to scrap it for the power supply - Link 250W low bander converted to 6M. Tall rack, 250TH. It's been sitting for 10 years, too pretty to junk or otherwise mess up.
http://bunkerofdoom.com/kd5oei/link/linkmenu/Link_250UFS/0003.gif

Those are about it on my real VHF collection.  I'll have to look into the W9RAN web site.  http://rantechnology.com/index.html
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« Reply #8 on: October 02, 2017, 11:13:22 AM »

This is a picture of the business end of my mutt, M151A1 communications jeep. One of the rules of the mutt is it can only accommodate radio equipment built between the sixties to the early eighties. The service life of that vehicle. Onboard now is a AN/GRC-106, VRC-12 and I have a URC-110 thatís onboard for VHF FM. Almost think that RF-403 may be a better choice as a example of a Vietnam era VHF-FM radio then the URC-110 just that would create the issue of trying to locate rocks for things like 146.52 Also tend to use 144.250 at a lot of the events. Recall that the radio did cover two or three meg split without issues but not much more. Donít remember how hard it was or if it was a different model for 24 volt operation.
More pictures of the mutt can be seen at the M&S Net page at:

http://www.mrca.ar88.net/Old%20Pages/Net/MandS.html

Did operate the GRC-106 on 3.875 AM last month up at Gilbert/MRCA event, the radio produces quasi AM running USB plus carrier in the AM mode but the receiver still keeps its product detector online so if the people you are talking with are off frequency you get a heterodyne.





* 20170916_100153.jpg (3684.85 KB, 4032x3024 - viewed 57 times.)
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« Reply #9 on: October 03, 2017, 09:37:10 PM »

That's a great setup. I have owned and repaired several GRC106/As, great radio. I'd like to find another fixer upper. I have the special very rare aftermarket LSB+USB filter for it. Fits in place of the original IF filter in the audio module and a operation switch position on the front can be sacrificed or a BNC jack replaced by a switch to select sideband.
If you want the RF-403 you can have it for shipping. This would solve the crystal issues.
http://rantechnology.com/four-channel-oscillator-board.html
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« Reply #10 on: October 09, 2017, 04:27:35 AM »

If I were in better financial shape, Patrick, I'd offer to take one of the Stoners (from a cursory Googling, 2-to-15 MHz? 80/40/30/20m, I wouldn't complain).  One big hurdle would be finding crystals, unless one were to lash a VFO to her, I guess. I understand a gent in England is offering crystals, but I've not looked into this in detail.
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« Reply #11 on: October 09, 2017, 09:04:21 AM »

Bomar is also back into making custom crystals, just got a couple pairs for old repeaters. Just email them.

http://bomarcrystal.com/
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« Reply #12 on: October 09, 2017, 12:48:10 PM »

The gent in England might be bry  carling.  Who is now stateside.

His crystals don't seem to have the best reviews.. I have no idea why.

--Shane
KD6VXI
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« Reply #13 on: October 13, 2017, 02:44:38 AM »

This guy was mentioned for crystal replacement. I have not tried the wares though:
W9RAN web site.  http://rantechnology.com/index.html
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« Reply #14 on: October 13, 2017, 09:25:59 AM »

QRP Labs also has their "Programmable Rock" for $18

https://www.qrp-labs.com/progrock.html

I have some and they work well.
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