[TMC] GPR-92

[Richard Knoppow]

    Yet another interesting TMC receiver is the GPR-100. I 
downloaded the instruction book our of curiosity and recognized 
it as the same receiver as the MacKay Marine 3020. There is a 
similar MacKay 3030 which looks very much the same but is 
probably a later model. I had thought that all MacKay Marine 
equipment was made by Federal Telephone, another ITT company but 
evidently not. I also got the instructions for the TMC GPR-110 
but it seems to have been designed for general purpose rather 
than maritime radio use. Again, I wonder if anyone has either set 
and, if  you do, what your opinion of them is.
    A note on the GPR-92, TMC seems to have gone back to the 
grounded grid first RF it used in the original GPR-90. The 
diversity version, the GPR-90 RXD has a more conventional pentode 
RF plus a re-designed BFO. The reviews of the GPR-90 say the BFO 
pulls, surprising in any "modern" receiver. I did not look at the 
BFO in the 92, which in general is quite different from the 90 
but evidently the GG RF stage was thought to have enough 
advantage to go back to it. From a design standpoint the 92 is a 
very interesting receiver.
    I rather think the GPR-92 was intended to provide a house 
built receiver to avoid the Hammarlund SP-600 in diversity 
receiver systems. TMC seems to have used Hammarlund receivers 
modified by Northern Radio. Eventually, Hammarlund produced the 
-17 which has all the diversity mods except for a gain trimmer, 
which could be added later. I think someone at Hammarlund was 
just asleep at the switch.
     You are all aware I am sure of the Hallicrafters version of 
the SP-600, Didn't quite make the grade although Hallicrafters 
did address the problem of drift from unregulated filaments.
    Oh, enough meandering.

On 3/22/2021 3:15 PM, W2HX wrote:
> Mine:
> https://w2hx.com/x/TMC%20Technical%20Materiel%20Corporation/GPR-92-SBE-2-PMO-5/GPR-92.JPG
>
>
> -----Original Message-----
> From: tmc-bounces at mailman.qth.net <tmc-bounces at mailman.qth.net> On Behalf Of Richard Knoppow
> Sent: Sunday, March 21, 2021 4:36 PM
> To: tmc <TMC at mailman.qth.net>
> Subject: [TMC] GPR-92
>
>      Not any traffic here lately so I will drop a rock into the pool.
>      I am curious about the GPR-92. Does anyone actually have one?
>  From what I've read not many were built. Evidently they were difficult to make and performance may have been partly wishful thinking. They are so sexy looking one wants them to be extra good but I think it was a miss rather than a hit. There is probably stuff in the list archive but I have not looked.
>

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL