[R-390] R-1247 Nasa Receiver info

[Meir WF2U]

The  R-1247/GRC-129 receiver is the nomenclature for the R-390A receiver
modified by Manson Labs.

The GRC-129 system was a high-stability diversity system used by NASA which
had two R-1247/GRC-129 receivers.  These modified R-390A’s had other
associated equipment manufactured by Manson Labs. The receiver was modified
to accept inputs from the external frequency synthesizers which generated
all the necessary LO frequencies.

The receivers can be switched over from internal to external LO operation
and for this purpose had small relay boxes and LO in/out cables/plugs. 
The IF output was utilized through an SSB converter (2 channel) which
provided the demodulated audio output (the BFO signal was supplied
externally from one of the synthesizers).

The CV-1693 is the 1 MHz step synthesizer and the O-1203 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.

I used to have the synthesizers for the GRC-129 system and I still have the
R-1247 receiver which works normally by itself - it has 2 tags: the system
tag "R-1247/GRC-129 Receiver, Manson Labs S/N 48, contract #
AF30(635)30962"; and the original R-390A tag: "R-390A/URR, S/N 1832,
Motorola, contract 14-PH-56".

 Hallicrafters also made some of the synthesizers under contract, for
Manson.

I also had another part of the same system, the O-1555/URC which is a
synthesizer to set the frequency of a modified T-368 transmitter whose
GRC-129 nomenclature eludes me. The component I never had is the SSB
generator that was added to the transmitter instead of the original
modulator deck. I also had some documentation on the synthesizers.

I sold all the accessories mentioned above maybe 10 years ago, with whatever
technical documentation I had, except I kept the R-1247 receiver which I
still have. It's usable as a normal R-390A without all the accessories.

I hope this clarified some questions. 


73, Meir WF2U
Landrum, SC

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Mack Rogers
Sent: Thursday, February 25, 2010 5:52 PM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] R-1247 Nasa Receiver info

I recall seeing some surplus dealers and even a few individuals that had the
complete AN/GRC-26D shelters with all the radio gear still intact but only
the shelters and gear, not still on the truck.

Which brings up the interesting question of exactly why something that was
supposedly for NASA use only would show up on the mil lists as being a
standard military piece of gear? AN/GRC-129 shows to be a standard
AN/GRC-26D with modifications? <big grin>

Could we be seeing one of those deals where NASA needed it but didn't want
to pay the price tag themselves? I used to see train loads of brand new
military heavy construction equipment, bulldozers and etc., going into one
of our TVA nuclear plant construction sites. A few days later that brand new
military construction equipment would roll out of the TVA shop repainted and
renumbered as TVA property!? <grin, wink>

73s
N4VGB
Mack Rogers

 



--- 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 info
> To: r-390 at mailman.qth.net
> Cc: "Mack Rogers" <n4vgb at yahoo.com>, "James M. Walker"
<chejmw at acsu.buffalo.edu>
> Date: Thursday, February 25, 2010, 5:34 PM
> Those 2 1/2 ton trucks set up as
> GRC-26Ds, were "pre-positioned" in 
> Europe.  A very large number in Germany around 30+
> years ago.
> 
> Send a message to WB2FCN! <James M. Walker> <chejmw at acsu.buffalo.edu>
> 
> He's whom saw them in big numbers.  Don't know about
> the AN/GRC-129.
> 
> Bob - N0DGN
> 
> On 2/25/2010 5:18 PM, Mack Rogers wrote:
> > Strange as it may be, the AN/GRC-129 shows up on the
> mil lists as being a modified version of AN/GRC-26D! Wonder
> where NASA parked those deuce and a half trucks!? (big grin
> and scratching head)
> >
> > SSB adapter for a T-368!? We could all go for one of
> those!
> >
> > 73s
> > N4VGB
> > Mack Rogers
> 
> 


      

______________________________________________________________
R-390 mailing list
Home: http://mailman.qth.net/mailman/listinfo/r-390
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:R-390 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html