[TMC] GPR-90 RXD Tuning

[Duncan Brown]

Steve,

One solution for the GPR-90, that many commercial stations used, is a 
preselector ahead of the GPR-90.  As one of my engineering managers used 
to say "there is no substitute for selectivity."  You can improve the IM 
performance, but there will be locations (like yours) where an 
interfering signal still causes problems.  The best way to cure it is to 
keep the interfering signal out of your radio!

(wish I had not sold my GPR-90 forty years ago!)

Have fun,

Duncan
K2OEQ


On 13-Mar-14 09:14, wb9tow at egr.msu.edu wrote:
> Excellent information on the TMC Receivers!
> Just a present day observation, I use a GPR-90 with
> GSB-1 on 40m CW about every day. The combination is
> not too bad depending on the "time of day". I live about 1 1/2
> miles from a 5KW MW BC station. Their station is off the air
> at night, which helps reduce the IM....
> I run a resonant antenna system and an ATU but still
> find the IM rejection quite poor.
> I've often wondered if there is a way to improve this design
> without destroying the value of the rx, but I think the best
> step is to acquire a GPR-90RXD or GPR-92....
> 73
> Steve w8tow
>


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