My K2/100 has been working great for the year and a half (except for a bad power cord once) since I built it, but it just recently presented me with a perplexing problem. Since I don't get on SSB very often, I don't know how long this has been an issue, but the symptom is that when I start transmitting in SSB, power is OK for about 3-4 seconds and then power shuts down to zero on both SSB and CW. When I remove the SSB board and install bypass jumpers (and recommended capacitor), the rig works perfectly in CW. When I reinstall the SSB board, same problem; i.e. 3-4 seconds of good SSB power and then power shuts down to zero. Thinking that the problem must be on the SSB board, I took voltage measurements on all the SSB board ICs. The only voltages from the IC voltage table that were off were these: U2-5 RX and TX was .47V rather than .6 (probably not significant?) U2-2 TX was 5.63V rather than 5.9V U2-8 TX was 3.1V rather than 5.4V U3-5 RX was .25V rather than .4V U3-6 TX was .64 rather than .8-1.2V U4-3 RX was .47V rather than .6V Anybody care to venture a guess on what these symptoms could mean? I'm not really an electronics guy so I'm just using the process of elimination to try and track this down, but I can't imagine that there is something on the SSB board that can shut the power down completely at both the QRP and 100W level. However, I have accidentally discovered that if I leave the jumper capacitor out of the jumpered condition (SSB board removed), there is no power, so maybe Q3, C39, D3 or C42 on the SSB board are the culprits with either a failure or bad solder joint. That where I will start looking tomorrow and hopefully you guys will have a suggestion or two to limit my random hunting process. ;-) By the way, for the guys asking about the value of used rigs, I was amazed that my other K2/100 (loaded) went at the Buy-it-Now price on eBay within 12 hours of being listed last Saturday. I got slightly more than I paid for the original rig and options, but a couple of bucks less than the current "new" pricing. I was very pleased. I'm expecting my first K3 within "two weeks" and the second one should show up in March/April. I'll be selling this second K2/100 at that time, but only after I track down this recently discovered problem. Thanks, Bob K5WA K2/100 #4687 K2/100 #5119 (just sold) K3/100 #2XX??? K3/100 #4XX??? maybe? _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft
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