[TMC] GPR-90 RXD vs RXDS

Sun, 25 Apr 2004 12:06:41 EDT

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, 
[email protected] 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)
<[email protected]> (Primary email)
<[email protected]> (Backup email)

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