Re: R4C Sherwood audio mod questions
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Floyd,
I had the same problem on my R4-C. I traced it to 3VPP of 60
Hz ripple on the +12v supply that powers the calibrator. That ripple, which was
caused by an open diode in the power supply, resulted in the tone sounding like
a buzz when using the calibrator, whereas the tone when using an external RF
source was a clean tone. You may not have 3 VPP of ripple on your +12 V line,
but be aware that any noise/ripple on that line does modulate the output
signal.
Bill N0CU
On Thu, Jan 9, 2025 at 8:51?AM Floyd - K8AC via <floydsense= [email protected]> wrote: Well, I decided to go ahead with the R4C transformer rotation and completed it this morning.? I was able to locate a new 5/8" Greenlee punch on eBay for a good price.? Took a lot of photos and notes so everything went back together properly.? There's definitely an improvement when listening to the calibrator at both ends of the bands.? I never noticed the same problem with CW signals and am wondering if the proximity of the calibrator board to the transformer might have something to do with the calibrator effect.? I don't have the equipment to look closely at the signal as Rob and others have done.? One slight oversight by me in the process: after removing the transformer, I removed the calibrator board so not to accidentally damage it while drilling and punching.? I reinstalled the transformer in it's new orientation and found that I couldn't get the calibrator board plugged in again due to mechanical interference with the transformer shell and the fact that the calibrator has rather long pins on the connector.? Replace the calibrator first!
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Since this is essentially a no-cost modification (if you already have the Greenlee punch), it's probably worth doing but I don't consider it a vast improvement, at least not to me.? Thanks to all who commented on the mod.
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73, Floyd - K8AC
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