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

[Dave Maples]

All: Considering that SAC replaced one of the vacuum-tube computer elements
with a solid-state device in 1983 (I remember the article in Aviation Week
and Space Technology, as well as other places) it's easy to understand why
they hung on to the 390s et al for such a long time.

Dave WB4FUR

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of Mark Huss
Sent: Sunday, June 05, 2005 11:24 PM
To: James A. (Andy) Moorer
Cc: r-390 at mailman.qth.net
Subject: Re: [R-390] R-390 "B" model


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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