[R-390] R-1247 Nasa Receiver FOR SALE

Fri Feb 26 09:14:12 EST 2010

John....

That's great info....in my mind a rare piece of history that clears up a 
piece of the R-390A/Manson Labs gray area as we thought we understood it.

You speak of loving to work on the stuff...that leads me to believe you 
posess some of the old synthesis gear that was used with these receivers. 
If I am correct maybe some photos for the archives would be in order.  You 
certainly don't see much if any of this stuff around these days and I would 
guess that piece will be lost forever in the not too distant future if not 
documented.

It's just this kind of stuff we need more of here...or future generations 
will have no clue...

Cecil Acuff
K5DL
----- Original Message ----- 
From: "John Vendely" <jvendely at cfl.rr.com>
To: "Richard W. Solomon" <w1ksz at earthlink.net>
Cc: <r-390 at mailman.qth.net>
Sent: Friday, February 26, 2010 7:54 AM
Subject: Re: [R-390] R-1247 Nasa Receiver FOR SALE

> The R-1247 was not developed for the Apollo space program.  It was
> developed in 1963 as part of the AN/GRC-129, a tactical RATT van used
> mainly by the Air Force.  The idea was to provide frequency synthesis
> facilities for the R-390A in SSB/RATT operation, solving the receiver's
> long-term stability problems.  Manson Labs modified stock R-390As to
> accept two external frequency synthesizers which substituted for the
> internal PTO, HF crystal oscillator, and 17 Mc oscillator.  The
> resulting system was thus phaselocked in 1 kc steps, and had much better
> long-term frequency stability than the stock receiver--when it worked.
> The synthesizers proved unreliable, and also degraded receiver phase
> noise performance.  Manson also supplied a SSB converter for the
> receiver, and a SSB exciter (CV-1695/GRC-129) for use with the system's
> transmitter, a modified T-368 from which the old exciter and modulator
> was removed, and to which the SSB exciter and new 1 kW linear amplifier
> were added.
>
> The "R-1247 developed for Project Apollo" story appears to have
> originated with a guy selling a grossly overpriced partial set of the
> synthesizers several years back, and has been circulating ever since.
> It's become a kind of urban legend in the surplus radio community.  NASA
> used many R-390As throughout its ground communications network from the
> beginning of Project Mercury onwards for HF reception and as a tuneable
> IF.  And I can attest to the fact that they did indeed purchase a few
> R-1247-style conversions from Manson Labs.  However, they were
> disappointingly unreliable, and were quickly removed from service.
>
> Conversion of older equipment to SSB and frequency synthesis was a big
> deal there for a while, and Manson Labs did a lot of business in this
> market.  They offered their upgraded R-390  systems on the commercial
> market as well, usually featuring a synthesizer system which tuned in
> 100 cps steps (Manson Laboratories Model 299).  However, they weren't
> very successful.  They also produced a very similar synthesizer/SSB
> upgrade for the Collins AN/FRT-24 transmitter.  TMC also did an R-390A
> synthesizer upgrade using equipment of their design.
>
> In all fairness, the reliability problems this equipment had were
> typical of that generation of vacuum-tube frequency synthesizers.  All
> the synthesized gear of the time, whether purpose-built or modified,
> required frequent attention to keep it going.  Manson's multiloop serial
> injection PLL synthesizers were audacious, state of the art designs for
> their time, and by far the most physically compact.  They were therefore
> tweakier than most.  I must say I greatly enjoy working on them though,
> perhaps for this very reason, and can recommend them to anyone who's
> also nuts enough to want to spend the necessary time at it...
>
> 73,
>
> John K9WT
> Malabar, FL
>
> Richard W. Solomon wrote:
>> I have to ask ...
>> What mods were done to it for the Apollo Program ? I doubt
>> they flew it !!
>>
>> 73, Dick, W1KSZ
>>
>>
>> -----Original Message-----
>>
>>> From: Brian Vietri <bvietri at msn.com>
>>> Sent: Feb 24, 2010 10:21 PM
>>> To: R390 LIST <r-390 at mailman.qth.net>
>>> Subject: [R-390] R-1247 Nasa Receiver FOR SALE
>>>
>>>
>>> This receiver was modified for Apollo Space Program.
>>> I have for sale Manson Labs R-1247 s/n 94. This unit is is great 
>>> condition, works very well, very clean, has some knob paint wear, top 
>>> and bottom covers and balanced antenna adapter. I have installed 600 
>>> volt Orange Caps in IF module, C603 and C606 Rebuilt, Inrush current 
>>> limiter installed. (Mfg Motorola R390A s/n 1818, Manson Labs s/n 94)
>>> Pictures available upon request.
>>> This unit is heavy approx 75 lbs, so it will be PACKED,SHIPPED and 
>>> shipped INSURED by UPS. Plz serious inquiries only.....
>>> WILL NOT SHIP OUT OF USA
>>>
>>> Asking $1350.00  OBO + ship + ins
>>>
>>> Paypal Preferred
>>>
>>> Contact Brian bvietri at msn.com
>>>
>>>
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>>
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>
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