[TMC] GPR-90RXD stuff

[George Maier]

Hi Chris:

I'm happy to send you a photo, but not sure it will get through the reflector, so I'll send it to you directly.  Meanwhile, I suspect that the inductor you are seeking (assuming it's L38) may not missing, but is located far from the BFO.  In my radio, L38 is between pins 5 and 6 of the 8 pin accessory power out octal socket on the rear panel while the tap goes to pin 7.  The 3 pf BFO coupling cap, C59, is connected between pin 6 of that socket and pin 7 of the 6AL5 detector.  

Hope this helps!

73, George

-----Original Message-----
From: Chris Bolkan [mailto:bolkyboats at gmail.com] 
Sent: Friday, August 06, 2021 1:13 PM
To: George Maier
Cc: tmc collector's group
Subject: Re: [TMC] GPR-90RXD stuff

Hi George!
I am a new member too and I also have an RXD. Mine is missing the tapped coupling inductor between the BFO and where it connects to the IF (at least according to the schematic I have). If you could take a picture of yours I would really appreciate it. I need to see what it looks like so I can figure out what I need to make to take its place.
This group is amazing and very helpful.
Chris

On Thu, Aug 5, 2021 at 7:00 PM George Maier via TMC <tmc at mailman.qth.net> wrote:
>
> Hi All:
>
>
>
> I'm a newbie to the TMC list, but an old timer in the hobby; first 
> licensed in 1958 as KN1GXT and K1GXT a year later.  The current call 
> sign was pretty much a mid-life crisis, but that was almost 20 years ago now.
>
>
>
> Regarding TMC, I've had lust in my heart for a GPR for decades, but 
> never owned one until now.  It's a Canadian made GPR-90RXD (ca 1971 
> vintage) that came with an original TMC cabinet and a matching TMC 
> speaker.  John P tells me that this a rare find so I'm wondering if 
> anyone in the group has seen any other Canadian made receivers.
>
>
>
> It's actually in very nice shape physically and works rather well 
> after some TLC and a complete alignment.  I'm still cleaning it up 
> here and there, and will probably have the cabinets repainted 
> professionally provided the color can be matched accurately.
>
>
>
> Does anyone know the actual color chip that was used, or have the paint
> formula?   Also, the speaker grill cloth must be replaced so I'm searching
> through all of the web based grill cloth resources, but have not found 
> a really close match yet.  My interior designer XYL has given me some 
> of her fabric catalogs to look through, so may I'll find something 
> there unless someone has a good resource.
>
>
>
> Last but not least, the BFO injection in this receiver was 
> ultra-wimpy, making it barely useable on CW and a waste of time on SSB 
> .  It's different from other GPR's in that the BFO is injected at the 
> detector while other models have the BFO injected at the grid of last 
> IF tube, except for the RXDS with its built-in product detector.  The 
> RXD is actually more like most Collins, Hammarlund, Hallicrafters and 
> National radios that do not have built-in product detectors, but their injection levels are much higher.
> Adding 20 pf to the original 3 pf BFO coupling cap made all the 
> difference in the world; it's now a very pleasant receiver on CW and manageable on SSB.
> Score one for the old guy!
>
>
>
> Any info or tips will be sincerely appreciated.
>
>
>
> Thank & 73,
>
> George - W1LSB
>
>
>
>
>
>
>
>
>
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