[TMC] Re: GPR90-RXD Receiver - Mod Info

[Mahlon Haunschild]

Mark,

You also have to make sure that you have the proper schematics/parts 
lists for your receiver.  There are at least two different GPR-90RXDs. 
Some modifications may be applicable to the earlier version, but not 
later version(s).

Mine (1967) is the one that uses a 6BA6 for the RF amp; the older one 
(1957) that I know of uses a 6AB4.  But those aren't the only differences.

That said, I'm curious about what modification info you turn up. 
Converting the RF amp to a 6BZ6 is sorta intriguing....

regards,

Mahlon - K4OQ

> Message: 1
> Date: Sun, 7 Sep 2008 20:28:39 -0400
> From: "Mark Johnson" <mvjohn at sympatico.ca>
> Subject: [TMC] GPR90-RXD Receiver - Mod Info
> To: <tmc at mailman.qth.net>
> Message-ID: <00a601c91149$d7840c90$0b02a8c0 at ibmdhuacy62dhv>
> Content-Type: text/plain;	charset="iso-8859-1"
> 
> TMC Team;
> I just picked up a GPR90-RXD and while it is working, its not as good as it should be. I can see someone has been into it and done some modifications. The area I'm into now is the Oscillator V12 and the external oscillator, V17. Someone has added a diode and resistor in the circuit that connects the two. 
> 
>>From experience, its nice to have a description of popular modifications that may have been done so that reversing them is easier. I suspect like most gear, various mods where published in popular Ham publications of the day....
> 
> Can anyone help or point me to possible sources?
> 
> Many thanks
> 
> Mark V Johnson VE3DJU/VE3DDI