Each time I had the warble on a receive, especially noticeable on a cw or calibrator signal, the cause was the 10 volt regulator card contacts being slightly oxidized. I pull the card, after removing the heat sink nut and bolt for the pass transistor on the side of the case of course, and clean the pins and all contacts. Replace the card and check the 10 volt rail. Rock the card a bit while listening to the calibrator tone. If you care to experiment, adjust the pot on the top of the board and you will hear the tone shift as the 10 volt supply is varied. (VCO is run off of this supply) That has worked a few times for my TR-7 down here in humid south Florida.
Good luck, Mike W4DL ----- Original Message ----- From: Laird Tom N To: Frank Krozel ; [email protected] Sent: Tuesday, December 12, 2006 8:26 AM Subject: [drakelist] RE: audio waveform has warble/hum on it! Guess what; I just pick up a TR-7 last week and I heard that voice warble on it too! Ever so slight, but I heard it. I checked into the Drake technical net over the weekend and no one on the net heard of that problem. The more I listen to the TR-7, the less noticable the warble, maybe it's dirty switch contacts and just the fact that I'm exercising them helps? Tom Laird W9QI Moline, IL. ------------------------------------------------------------------------------ On Behalf Of [EMAIL PROTECTED] OK, my TR-7 is getting back in line to what it left Ohio many years ago. I have been listening pretty critically on the receive and it seemed on SSB like there was a slight warble on the audio. When going to CW it was harder to hear but still there. (I listen to 35+WPM so maybe I couldn't hear it.) Went to the Calibrator and it seems like the 25kHz calibrator signal is "jumping" up and down (in voltage) slightly, maybe +/- 3% or so on the scope. Audio-wise it is hard to hear but.. it is there - warbling ever so slightly. There is also some sort of "other signal" in the background. The other signal is much lower in frequency, maybe 60Hz? but the same amplitude! The scope seemed like it had problems syncing... Any thoughts on this? Frank KG9H
