[Drakelist] R4C BFO Leakage
A few weeks back I wrote about PBT levels in SSB/AM modes. It would change S-Meter levels depending on adjustment of the PBT. I ruled out the 4NB board by removing it..no change. However when I removed the bottom cover almost 6 S-Units of PB feedthrough were reduced and performance was enhanced with less white noise. Interesting to know the interference is being conducted by the metal bottom cover to key area's of the bottom chassis. Next I will attempt adding metal shields to isolate internal RF from conducting to nearby by circuits that are prone. Best 73 Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4C BFO Leakage
Have you been able to remove the NB-4 and bypass it with the jumper plug as yet? I have experienced this problem and I have found the NB-4 to be the culprit. You may be embarking on a process to eliminate symptoms rather than fixing the problem. JB From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net] On Behalf Of Bill Becky Sent: Thursday, 12 July 2012 9:21 AM To: drakelist@zerobeat.net Subject: [Drakelist] R4C BFO Leakage A few weeks back I wrote about PBT levels in SSB/AM modes. It would change S-Meter levels depending on adjustment of the PBT. I ruled out the 4NB board by removing it..no change. However when I removed the bottom cover almost 6 S-Units of PB feedthrough were reduced and performance was enhanced with less white noise. Interesting to know the interference is being conducted by the metal bottom cover to key area's of the bottom chassis. Next I will attempt adding metal shields to isolate internal RF from conducting to nearby by circuits that are prone. Best 73 Bill KB9IV ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4C BFO Leakage
Check and make sure that all the shielding underneath for the 3rd mixer is intact. That circuit is very sensitive to stray signals and noise. You might also want to try a different 6EJ7 in there to see if it changes anything. 73, Steve Wedge, W1ES/4 Time flies like an arrow; fruit flies like a banana. All my computers have my signature with various pearls of wisdom appended thereto. From: Bill Becky Sent: Wednesday, July 11, 2012 7:20 PM To: drakelist@zerobeat.net Subject: [Drakelist] R4C BFO Leakage A few weeks back I wrote about PBT levels in SSB/AM modes. It would change S-Meter levels depending on adjustment of the PBT. I ruled out the 4NB board by removing it..no change. However when I removed the bottom cover almost 6 S-Units of PB feedthrough were reduced and performance was enhanced with less white noise. Interesting to know the interference is being conducted by the metal bottom cover to key area's of the bottom chassis. Next I will attempt adding metal shields to isolate internal RF from conducting to nearby by circuits that are prone. Best 73 Bill KB9IV ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
