[TMC] GPR-90RXD stuff

[Chris Bolkan]

Hi George,
Thank you! I would appreciate that pic and yes just email directly.
I will look again, but I am pretty sure it is not there because I
traced it all out and ended up capacitively coupling the BFO signal
into the IF. Would be awesome if I am wrong! My goal is to make the
receiver original, and then like everyone else, find an SSB adapter. I
am looking for one of the rack mount adapters though because that is
how I will ultimately mount the receiver.
Best regards,
Chris
KI7NXY

On Fri, Aug 6, 2021 at 11:11 AM George Maier <GeorgeW1LSB at verizon.net> wrote:
>
> 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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