On Mon, Feb 16, 2009 at 09:24:32AM -0800, James Cobb wrote:
I'm trying to decide what I should do for a power supply for my
TR-7. I'll try to give the Reader's Digest version, but I have a slight complication. My main power supply is an Astron RS-35M, but my TR-7 (S/N 46xx) generates some transmitted audio feedback in the receive audio when used with the RS-35M. I've used 3 other HF radios on the Astron and none of them have glitched and a full alignment on the TR-7 didn't cure the problem either. A few weeks ago, I tried running the high-current power lead off the Astron and the low-current lead from an MFJ-4125 switcher and the transmitted audio feedback totally disappeared. When using only the Astron, I was also getting some dimming of the panel lights which does not happen with the other radios. My guess is that my Astron has a slight issue. The MFJ-4125 doesn't provide enough current to run the whole radio which brings me to needing to do something about the power supply setup. Early Astron power supplies were built with the negative terminal grounded. Some of the later (and current if you will pardon the pun) ones are not. This is so you can combine two in series to double the output voltage. Check to make sure that negative terminal is in fact grounded on yours. If you think that the problem is low power output try reducing the output power of the TR-7 and if it goes away, that is also a problem. Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel g...@mendelson.com N3OWJ/4X1GM _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
