[R-390] R 1981 R 390A Receiver
Tom Frobase
tfrobase at gmail.com
Mon Feb 21 20:49:46 EST 2011
I found a similar unit a couple years ago, it was a 1958 Motorola.
If you look at the three mods when energized it allows an external
oscillator to inject in place of the on board functions PTO 1st IF and
2nd IF. The set should work as a normal R-390A without the relays
energized. If you look back through the list a couple of folks talked
about the set up being used for diversity reception.
I ended up removing the mods, no moving parts, and restoring the set
back to a really clean R-390A it is what is in my shack today. 73,
tom, N3LLL
On 2/21/2011 8:17 AM, wa4aos at aol.com wrote:
>
>
>
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> Hi Group,
>
> In my ever growing collection of R 390, R 390A and R 392 equipment, I have just received an R 1981 ( R 390A) There is not much on the web about this one and I am wondering if there are other examples out there?
> My good friend Jon, K1VVC, found it at the Richmond Frost Fest this year; we have agreed on a trade and I now have the unit. I have not pulled modules yet but the Power Supply is an Amelco. Just a
> quick look over and my initial guess.is the rest of the modules are Amelco as well; not an EAC as I had heard but a very nice example nevertheless.
>
>
> I pulled this off the web:
>
> The R-1981 was a R-390A modified to bring out the 17 MHz, HFO and VFO signals to the rear panel andto insert an error correction signal for high-stability operation. It was a part of the TSC-25communications system. The modifications were done using a kit of parts from The Technical MaterialCorporation (TMC) under contract number 14385-PC-58. The manufacturer of the R-1981 receiver isunknown. If anyone posesses one or knows of its history, send mail to the FAQ-Meister so we can share the information.
>
> When I get it in the lab, I'll take pics and post them on my web page. I am fortunate that this example is in very good shape, possibly an 8 on the 10 point scale.
> Any other info would be greatly appreciated.
>
>
> Glenn Scott WA4AOS
> DSM Labs
> w w w dot dsmlabs dot com
>
>
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