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

[John Vendely]

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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