On Wed, Jan 4, 2012 at 8:11 AM, Steve - W6SDM <[email protected]>wrote:
> ** > > > Have you tried another firewire cable? Or, better yet, have you tried a > Granite firewire cable? I can't say enough about the improved performance > from the quality of the cable and the extra shielding. > > I assume you have checked for ground loop and that you have the computer > cabinet grounded. > > Other than that, and from what has been suggested here, I am ready to > suggest sacrificing a goat at the base of your antenna mast as a possible > solution. :) > > Good luck - I am sure that the cause of the problem will surface. > OK, he has pretty much determined that it still has the problem with a dummy load, and with the radio and computer removed from the shack. That makes it pretty clear that this is NOT an RF problem. The only commonality is the mic cable. Looking at the schematics for the 5000 and 1500 (I don't have the schematic for the 3000 but it seems to work the same), the mic input on the radio is cap coupled. I must admit, I use this to good effect by putting my bias resistor directly between +5V and Mic+ in the mic connector in order to get the bias to the electret mic element. That works and I have no problems. But if one were to switch that voltage, I would definitely expect a "thump" as the +5V is switched to Mic+ due to the charging of that coupling cap. I have a 3000 that does not exhibit any problem like this as do many other people. So what is different about this setup? I keep thinking about the mic cable and mic switching. The other possibility might be the power supply momentarily losing regulation when the sudden load of the PA bias comes on. I would try switching power supplies because that is an easy thing to do. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 [email protected] +1.767.617.1365 (Dominica) +1.916.877.5067 (USA) _______________________________________________ FlexRadio Systems Mailing List [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
