[R-390] R-1247 Nasa Receiver info

[Steve Toth]

I have one of these.  It's an R390A with mods for external connection to two high stability frequency oscillators, one was used for Megahertz and one was used for Kilocycles (not included and mostly unobtanium and very expensive IF you can find them - although I seem to remember from a previous thread that someone here on the list has a set of the oscillators).  No changes in internal components from a standard R390A except the modified PTO and plug in crystal oven crystal can - it still uses the interchangeable power supply, IF, RF and audio decks but NOT the standard PTO.  Alignment and calibration is the same as a standard R390A.
 
FWIW:
Pro:  It is unique and has a certain amount of "cool" factor as being an unusual version of the R390A.  You also get bragging rights to owning an R390A "that was modified to be used in the Apollo space program".  A genuinie R1247 will have a couple easily seen mods: the three connector plate mounted on the upper rear panel with three jacks labeled "J1A, 17Mhz input", "J2A, Synth Input" and "J3A, 9-17Mhz" input.  You will also find a mod to the PTO (two mini BNC connectors just below Z702 with input cables) and Mod 1 labelled on the corner of the audio deck closest to the PTO.
 
Con (from a strictly practical standpoint only): The mod inserts relays into the oscillator signal paths.  It just adds one more minor thing (dirty relay contacts over time) to go wrong and degrade receiver performance.  It's still an R390A and is a great receiver, its uniqueness just adds one more minor aspect to its ongoing maintenance.
 
 
More Info:
 
R-1247/GRC-129

The radio receiver R-1247/GRC-129, HF, 500 Kc to 32 Mc, is a high stability version of R-390A/URR using external ultra-high-stability oscillators. Used by NASA for the Apollo program and modified from the R-390A by Manson Labs.

Contract info: Manson Labs, contract AF30(635)30962 ,Part No 224-0A2

Additional info per Tom, N5OFF:
" All the Oscillator outputs were in series through sets of 2 DPDT relays that
appeared to allow the R390A to use its own Oscillators, Import external oscillator
signals, or export its internal oscillators to a set of BNC jacks on the rear panel.

By all the oscillators I mean PTO, 17Mcy XTAL, and the 1st conversion xtal. These 
relays required external power via a small connector labeled CONTROL.

The relays were Mil Spec commercial units mounted on well machined casts that
fit into the OSC tube sockets on the PTO and Heterodyne osc. and the one for 17mhz xtal plugged into the socket for crystal oven. There were 2 small dia. color coded coax 
cables going to each relay.  The R390a worked normally with no connections to any of 
the connectors."
 
Additional info per WF2U Landrum, SC
This equipment was part of the AN/GRC-129 system which had 2 R-1247 receivers for dual diversity.  The 2 receivers had the CV-1694/GRC-129 Single Sideband Converter, (Manson Labs) connected to them, The CV-1693/GRC-129 is the 1 MHz step synthesizer and the O-1203/GRC-129 is the 1 KHz step synthesizer locked to the same frequency standard. 
 
With the 2 synthesizers the receiver is tunable within its normal frequency range in 1 KHz steps. The frequency still has to be dialed in the receiver, because the RF stages and mixers have to be peaked up at the frequency of operation. The receiver can be operated normally, too. 
 
Both synthesizers and the converter were built by Manson Labs, but the synthesizers were also made under contract by Hallicrafters, in their last throes of death.
 
The system transmitter was the modified (for sideband) T-368, under the nomenclature T-946/GRC-129, driven by the O-1555/URC synthesizer. 
 
-- Steve 






Woodinville, WA

 

--- On Thu, 2/25/10, rbethman <rbethman at comcast.net> wrote:


From: rbethman <rbethman at comcast.net>
Subject: Re: [R-390] R-1247 Nasa Receiver FOR SALE
To: r-390 at mailman.qth.net
Date: Thursday, February 25, 2010, 11:34 AM


Mack,

It will only go for what someone is willing to pay.

The add-ons by Manson Labs are useless!  There is no way of getting the 
external equipment that is designed to connect to the modifications!  
(Another BIG Smile!)

I won't belittle someone's offerings or desired price!

It belongs to him, he has every right in the world to place a price on 
it that HE feels is proper.

Folks like you and I won't be making offers.  (ROTFLMAO!)

Bob - N0DGN

On 2/25/2010 1:58 PM, Mack Rogers wrote:
> Unless you own some of the external auxillary gear to go along with a R-1247 rcvr, it's just an R-390A with more connectors on the back. (big smile)
>
> An unusual collectors item, yes, but still just a R-390A.
>
> N4VGB
> Mack Rogers
>
>    
>> 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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