[TMC] GPR-90 RXD vs RXDS

[Mahlon Haunschild]

The only "GPR-90RXD" schematic I've been able to find is located at:

http://www.geocities.com/tmcradio/gpr90rxschem.gif

note that the link to this page from

http://www.geocities.com/tmcvintage/manuals-editorials.html

is labeled "GPR-90RX Schem (big)" which appears to be an inaccurate 
description.  The schematic itself is labeled GPR-90RXD.

<carlin>
"Well, it's a mystery..."
</carlin>

regards,

Mahlon - K4OQ

WA5CAB@cs.com wrote:

> Mahlon & Group,
> 
> The base GPR-90 (no letter suffix) schematic shows E2 as the audio out 
> terminal strip and the 300/75 ohm antenna terminal strip is not labeled 
> (error on schematic I suppose).  The GPR-90-RX schematic in NAVSHIPS 
> 93165 calls the 300/75 ohm antenna terminal strip E1.  I'm not sure what 
> web site has a schematic ID'd as for the GPR-90-RXD but if that 
> schematic does show the 10-position crystal addition then maybe it's 
> really the GPR-90-RX rather than RXD.  Wish I had the RXD manual but the 
> only thing I've turned up labeled RXD is that sales flyer, which answers 
> no questions.
> 
> BTW, per an addenda in the NAVSHIPS, there was a mod of the RX done for 
> some Canadian order where individual trimmer capacitors were put across 
> each crystal socket.  And the HF crystal oscillator tube was changed to 
> a 6CB6.  Mod is called CAN-1A.
> 
> In a message dated 4/25/2004 10:38:20 AM Central Daylight Time, 
> mahlonhaunschild@cox.net writes:
> 
>> I received my manual from Robert &did a quick compare.  Here's what I
>> noticed:
>>
>> - Per Richard's message, the "D" does indeed use a 6AG5 for the BFO,
>> while the "DS" uses a 6BE6 in a much more complicated circuit (probably
>> contained in the "can" that the tube plugs into).
>>
>> -  The "D" does not have a hi-Z IF output, the "DS" does.
>>
>> -  There appear to be minor differences in the rear apron layout.
>>
>> -  On my "D", E1 terminals 1 and 2 are rubber-stamped "AVC IN and OUT"
>> according to their function (no circuit differences that I can tell).
>> The "DS" pic in the manual doesn't indicate these rubber stampings, but
>> does correctly indicate a wire jumper bridging the terminals.  Note that
>> the "D" schematic on the web site shows E1 as the receiver antenna
>> input, with a 300 ohm/75 ohm balun behind it.  Mine has a BNC 75 ohm
>> input only (same as the "DS" apparently).
>>
>> -  My "D" has a BFO input jack on the rear apron; the "D" schematic on
>> the web site doesn't show this.
>>
>> -  My "D" uses the aforementioned 6DC6 &6BA6 as the 1st and 2nd RF
>> amplifiers, instead of the 6AB4 and 6CB6 that the "D" schematic on the
>> web site shows.
> 
> 
> 
> Robert & Susan Downs - Houston
> <http://www.wa5cab.com> (Web Store)
> <wa5cab@cs.com> (Primary email)
> <wa5cab@houston.rr.com> (Backup email)