[R-390] R-390 "B" model

[Mark Huss]

In a manner of speaking, yes. 
There was a limited production run of R-390A's with an electronic 
digital display.  Used analog mixers on the three Local Oscillators 
before connecting it to a TTL Frequency counter.  This was before 
microprocessors.  Another allowed the oscillators to be sync'ed to a 
Master Oscillator.  Used by NASA.  Nothing went into major production, 
probabily because the R-390A just worked so well.  I was in when the 
Army was getting rather desprate to replace it with a solid state 
receiver.  They would buy hundreds of Watkins-Johnsons, Collins, Racals, 
even JRC's.  Each time after comparing sensitivity, selectivity, 
maintenance requirements, reliability, and operator preferences, they 
kept going back to the R-390A.  Finally, in the early eightys, they gave 
up and bit the bullet because of replacement costs and the growing 
requirements to remote control radios via data links and went with the 
Racal 6030A.  Even then, a few R-390A's somehow fell off the back of the 
garbage truck to end up in out-of-the-way racks for when the listening 
got serious.

James A. (Andy) Moorer wrote:

> Has anyone actually seen one of these? Did they ever build any?
>
> James A. (Andy) Moorer
> www.jamminpower.com
>
> ----- Original Message -----
>
>>
>> Phase D: Construction of "B" Model Receiver.
>>
>
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