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Re: R-4A BFO Gremlins


 

YES, even my 13 tube R-4A had fast AVC with a gassey tube! (only until Garey told me I had a
gassey tube!).

But, the best tubes in an R-4B will still give the too fast AVC.? You can tell if an R-4B is stock by
watching the s-meter on YouTube videos.
73,
Gary
WB6OGD


On Mon, Dec 30, 2024 at 4:49?PM Richard Knoppow via <1oldlens1=[email protected]> wrote:
? ? ?You have my sympathy with your move. My least favorite thing is
moving. Done it too often in the past. Right up there with surgery but
at least with surgery someone else does it for you.
? ? ?I found the AVC on my 4B is sensitive to gassy tubes. If gassy the
AVC acts as you describe rather than hanging.

On 12/30/2024 4:29 PM, Gary WB6OGD via wrote:
> Richard,
> I think the Product Detector mod is quite worthwhile.
> If you've ever used an R-4 or R-4A(13 tube) you will notice its? VERY
> nice and slow AVC on ssb.
> You can see the s-meter virtually hang on the highest audio peaks.
> Drake eliminated the tube product detector and went to two diodes in the
> 11 tube R-4A and kept it to the last R-4C (I believe).
> It was simpler, solid state but it caused detected audio to get back
> into the AVC, making it into a Fast (or medium) AVC.
> You can watch the s-meter dance around on sylables and hear the harsher
> audio as noise is allowed in between sylables.
> Rob also found problems like the signal exceeding the BFO on AVC attack
> (if I recall correctly) and that may be.. but that's
> above my pay grade, I never noticed that.? But now my R-4B sounds like
> my old 13 tube R-4A with its slow AVC.
> I gave away a lot of boards, someone may be able to give you one.? I
> might have a few more if I can find them after my move.
> My board is SMD.? The NE-602/SA-612(?) is now obsolete, you might have
> to get some from china?
> 73,
> Gary
> WB6OGD
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998






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