[TMC] GPR90-RXD Receiver & SSB

[Woody Demitz]

Over fifty years ago, when I was a teenager studying for my novice license,
I had a friend and classmate whose father was the commander of the US Navy
receiving station at Cheltenham, MD. This was the famous "NSS" often worked
by hams on Armed Forces Day. In the course of a visit there one day, I
talked with a Navy communications tech who was evaluating a pair of GPR-90s
for possible use in monitoring.  I thought they were the most beautiful
receivers I had ever seen.  The tech said, "they look great, but their
stability is s___." They're still, in my eyes, gorgeous, but I have never
forgotten that remark.

 

From: tmc-bounces at mailman.qth.net [mailto:tmc-bounces at mailman.qth.net] On
Behalf Of Mark Johnson
Sent: Sunday, December 14, 2008 12:04 PM
To: tmc at mailman.qth.net
Cc: Albert Santangelo
Subject: [TMC] GPR90-RXD Receiver & SSB

 

I recently acquired a GPR90-RXD receiver and did a pretty thorough overhaul
and alignment. I replaced some weak tubes, a few leaky capacitors and as
mentioned, I then did a very thorough alignment using better than average
test gear. 

 

While the sensitivity is good and the receiver is OK, I find that using it
for SSB or even CW, it is not as good as other receivers I have of similar
genre. I have to back the RF gain control off to the point where sensitivity
suffers or it will overload. I increased the value of the coupling capacitor
from the BFO circuit and that helped a bit but as mentioned, other receivers
of similar genre are better even though they, like the GPR90-RXD, don't have
product detectors. 

 

>From the experience of others, is this common for this receiver?

 

Overall I have to say I'm disappointed with the receiver. I've had many
"Boat Anchor" receivers over the years and always wanted on of these TMC
receivers. Its no where  close to any of the Collins receivers, R390's, 51j
series, or even my RCA CR-91a. 

 

What's the experience of others?

 

Mark V Johnson VE3DJU/VE3DDI

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