[R-390] Modification?

[Sheldon Daitch]

Let me ask a question regarding the synthesized
R-390 and variants.

I only saw personally one 390 system with the
Manson Labs synthesizers, either at Fort Monmonth
in tech school or maybe in Phu Lam, Vietnam,
at the HF receiver, so I know it was not at a
NASA operation.

What was the cross mix between the Army versions
of the syntehsized 390s and the NASA versions,
were they really the same systems, just that NASA
bought some and the Army bought some, or were these
systhesized system systems totally independent
animals/purchases and not even the same
synthesizer systems?

73
Sheldon

Tom Norris wrote:

>
> On Oct 18, 2006, at 11:14 PM, ToddRoberts2001 at aol.com wrote:
>
>>
>> It looks like an R-1247/URR variant of the R-390A. These had  
>> external inputs
>> for the 1st, 2nd and 3rd Local Oscillators on the rear panel that were
>> provided by an external synthesizer for high-stability operation  and 
>> were supposedly
>> used by NASA in the Apollo space program. The radio can be tuned  
>> like a normal
>> R-390A without the external synthesizer. Several small relays  inside 
>> switch
>> it over for use with an external synthesizer when needed. 73 Todd  
>> WD4NGG
>
>
> Yea, it's got the rear panel for it, and from the pictures there are  
> some of the cables inside.  I wonder if all the "guts" for the rest  
> of it are there?  Only the radio is collectable.  Used to be folks  
> like Rick Mish would remove and toss the adaptors and other things  
> that were inside.... myself, I have the synthesyser decks, but I'm  
> not sure I'd ever use it either since you still have to tune the  
> radio to frequency THEN tune the very noisy 60's vintage frequency  
> synth decks.
>
> Interesting thing, weren't the 1247's  (I apologize to Barry for the  
> typo, I'm really asleep right now) normally later model radios?  The  
> Manson radios I've seen looked to be 1967 EAC's - or at least later  
> than what appears to be either a 56 or 58 Motorola (with an R-390/URR  
> long tag to fill the empty space).
>
> At least this one has the audio transformer problem solved, like  
> what's been discussed here on the list.  Looks like there is one of  
> the small 600:8 ohm can transformers mounted on a bracket just  
> underneath the terminal strip behind the power supply.
>
>
> Tom
>