Thanks, Don--I do have the same symptoms when I connect paddles and hit the dot paddle in SSB mode--I'll try the adjustment you recommended and keep working at it.
73 de aa0ms On Mon, Feb 8, 2010 at 6:08 PM, Don Wilhelm <w3...@embarqmail.com> wrote: > Doug, > > Start with the easy things first - it could be RF Feedback or some type of > oscillation in the mic itself - or it could be a lack of carrier balance on > the KSB2 board. To check quickly, do not connect a microphone at all - just > connect your paddles to the key jack, and in SSB mode, close the dot paddle > (the DOT line inside the K2 is the same as PTT). Do you have any power > output? You should not because there is no audio. If you do have RF > output, the first step is to adjust the carrier balance pot on the KSB2 > board for minimum RF - you may have to compromise between LSB and USB, but > the carrier level should drop to a very low level at the correct adjustment > point. That point should be near mid-range on the pot, if it is not, then > look for a problem. > Once you have the carrier balanced, it is time to try the microphone again > - since you now know the carrier balance is correct, this time suspect RF > Feedback (or audio feedback if you have a computer soundcard also connected) > if it happens when the mic is added. > > There are other possibilities such as a problem in the ALC section of the > KSB2 board, but try the above before doing anything else. > > 73, > Don W3FPR > > > Doug Heacock wrote: > >> I dusted off my old K2 recently and decided to try to wire up an electret >> mic and give SSB a try--I've had the SSB module since I built the K2 years >> ago, but just never used it, because I had no mic at the time. I've >> discovered that when I ground the PTT line with the K2 in LSB or USB mode, >> I >> get the "Hi Cur" message, and my output power goes to well over 15W, >> regardless of the setting of the power output control. >> >> I've done some of the voltage checks recommended in the SSB module manual, >> but only those for RX mode--I'm a little nervous about trying to measure >> voltages in transmit mode, because I don't know how long the PA can take >> that kind of current, and I don't want to fritz the final or cause other >> problems. There are some voltage discrepancies associated with U2--pin 5 >> on >> that device is supposed to have 0.6v in RX mode, but I'm seeing more like >> 2.5v. Pin 3 of U4--same story. >> >> If anyone out there has any suggestions for where to look for problems, or >> how to do further testing, I'm all ears. I found an old thread in the >> list >> archives that suggested replacing Q3 and/or Q4 on the K2 control board, in >> case one of those 2N7000s happened to take a static electricity hit, but I >> haven't had a chance to do that yet (don't have any 7000s lying around), >> and >> I'm somewhat hesitant to go down that path because this rig seems to work >> just fine in CW mode. >> >> Many thanks, Doug >> >> > -- Doug Heacock Director of Media and Communications Contemporary Worship Leader Lawrence Free Methodist Church Lawrence, KS dheac...@lfmchurch.org http://www.lfmchurch.org ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
