I have another D201a that had low SSB modulation. I started with setting the bias. I set the AM and LSB bias for -40. LSB R707 trimmer was on the stop to get there. (I found the am set at -8) Then to neutralizing the tube, final tuning etc. This is where it gets a little funky. Down to line 15 of the neutralization procedure in the service manual. 15 and 16 says, LSB tx, Turn R707 (SSB Bias) for a reading of .37v at pin 8 of V701. All this adjusted fine. A this point I still have very little modulation on SSB (maybe 2-3w) and I noticed the meter kind of bounces up and down. When I check the voltage at the junction of R709, R710 I have -40v. Line 17 says I should typically have -55v by this point. I can adjust the trimmer and the voltage will read -55v with no problem but this leaves .14v at pin 8 of V701. I did try to modulate at -55v and she came to life. Over 20 watts on LSB and USB. At this point I shut it down and started typing. LOL. I just want to make sure this would be ok or do I need to look deeper? I do not want to kill tubes or have a melt down.
Thanks guys for your help so far!
Thanks guys for your help so far!