[GreenKeys] R-808 ///// AN/GRC-14

[WF2U]

Scott,

You said almost all I could have said about the GRC-14... I'm not so sure
whether it's newer than the GRC-19. It's certainly built by Navy standards,
and by a favorite marine radio manufacturer, Federal Radio.
The power supply indeed is a strange creature, as the 115VAC input option
runs the 24 VDC dynamotor, the transformer/rectifier adding probably a good
40 lbs to the overall weight.
The frequency generation is really not a synthesizer, it's really a phase
locked loop master oscillator stabilizer which has to be pre-set to the
frequency in order to lock the tunable master oscillator. The MO has to be
tuned with a calibration chart, as it has no direct frequency readout. The
MO is stable enough by itself, after a warm-up period, so it's usable
without locking the loop. I guess for extended periods of RTTY ops, over
rough terrain, the stabilizer (if and when it works) will prevent the MO
from drifting.

Power supplies are harder to come by than even the T-631/GRC-14
transmitter - I heard stories that they went overboard first, when the sets
were replaced... It was a short-lived radio set.

I'm not sure whether the Marine Corps hasn't got GRC-19's as replacements
for the GRC-14, even for a short time as once I saw a T-195/GRC-19 with USMC
stenciled on the case.

I have a complete GRC-14 setup, without the M-38. I'm trying to get the
transmitter running. It has low output but I don't think it's the finals.
The latest fault is that it doesn't go into transmit when keying - so there
must be another glitch in the keying circuit and/or relays. If and when the
set works, I'll hook it up to the M15 for a little RTTY fun.

Another remark, regarding the R-808 receiver: It's a plain double conversion
receiver, unlike the R-392/GRC-19, which has the standard Collins conversion
scheme with crystal conversion in 1 MHz bands covering the frequency range
feeding into the variable first IF. An advice with the R-808: in case of a
noisy, unstable receiver, the contacts of the RF head have to be cleaned,
the subassembly reseated and locked on the contacts.

Have fun!

73, Meir WF2U
Landrum, SC

> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net
> [mailto:greenkeys-bounces at mailman.qth.net]On Behalf Of Scott Johnson
> Sent: Tuesday, May 09, 2006 9:10 AM
> To: Nell, Paul C.; greenkeys at mailman.qth.net
> Subject: Re: [GreenKeys] R-808 ///// AN/GRC-14
>
>
> Paul-
> The R-808 was part of the GRC-14 set procurred by the navy for
> USMC use.  It
> seems to be a case of interservice rivalry, because although the
> GRC-14 is a
> newer set, its performance fall short of the GRC-19 in several
> areas. It is
> almost twice the weight of the GRC-19, the power supply alone weighs 190
> LBS!  The GRC-14 consisted of two R-808's, the transmitter, power supply,
> TTY, and a big alternator with a selenium stack rectifier that mounted in
> front of the radiator on the M-38A1 that hauled the whole mess.
> It does have
> some interesting features, such as built in RTTY converters, etc. The
> transmitter frequency is selected by decadic knobs, in sort of a
> rudimentary
> tube-base synthesizer, which can also be operated as a MO if the
> synthesizer
> crumps. The power supply design is way beyond stupid.  If AC operation is
> contemplated, a tranformer-rectifier unit supplies 28VDC to the largest
> dynamotor I have seen.  (I am, however looking for a power supply to
> complete my GRC-14).  In my opinion, the USMC should have used
> the GRC-19 in
> the GRC-46 equipment configuration. I'm sure this is what
> ultimately brought
> about the TRC-75, a 1KW SSB set that weighs less than the GRC-14!
>   At any
> rate, the R-808 is a nice receiver, and it even has a few transistors!
> (Check out the doorknobs behind the little plate up in the LH
> corner of the
> front panel)
> I have the manual and could copy the pertinent receiver material if you
> like.
>