[TMC] Need help with several GPR-90RXD puzzles

[WA5CAB at cs.com]

John,

I have a copy of IN-3005S (reprint $20 plus shipping).  The schematic is 
split over two 11x30 sheets.  It might match what your third unit originally was 
except that I don't see an L38.  V9 is a 12AT7 with section one diode 
connected.  The rectifier is solid state.  And the BFO is an octal plugin using a 6BE6. 
 It is a product detector, even though what's written on the schematic is 
just BFO.  The 12AT7 diode detector is biased off with about 75 volts on the 
cathode when the BFO is turned on.

I also have TB-3005A on the RXD but it's just a 4-page booklet listing all of 
the specs.  Probably a sales bulletin.  No schematic.

In a message dated 9/15/2007 3:55:13 PM Central Daylight Time, jp at cs.unc.edu 
writes: 
> 3.  This radio is labelled as a GPR-90RXDS.  It has the same plug-in filter
> cap as #2, but no 5U4.  Instead there is a pair of solid-state rectifiers, 
> and an additional power resistor, presumably to drop the B+ a bit to match 
> the voltage on the original tube rectifier.  This radio also has a 12AT7 at 
> V9, 
> instead of the 6AL5, and has the same octal 6BE6 plug-in unit as #2.  This 
> radio is serial # 34459.   To make matters more confusing, this radio has 
> been
> seriously hacked.. there's a bunch of solid-state circuitry that appears to 
> be
> a DC filament supply for the 3.9 MC 1rst IF unit.  Clearly not factory 
> original.

Robert Downs - Houston
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