I think in today’s technology, any amp recommending to run the radio at full power and expecting the ALC to protect the amp is a joke. It may not be fast enough to protect the LDMOS device.
SPE America has a history of pointing the finger at the radio having a power overshoot as the cause of LDMOS failures. Why did SPE now come out with a version 3 of the amp which redesigns the LDMOS input to help protect against accidental overdrive.? Why run a radio at full power if you have a radio that can be adjusted to the proper drive level per band? Dave wo2x Sent from my waxed string and tin cans. > On Dec 31, 2021, at 11:51 PM, Bill Frantz <[email protected]> wrote: > > After reading all the comments on this thread, I think that Skip, K6DWG and > Bob, K4TAX have the best theory of what happened. Careful reading of the SPE > 1.3K manual indicates that the power output of the amp is sampled between the > amp and the internal tuner and that the recommended tune power is 30W. > > So the idea that the tuner could have gotten into a state where it ate the > output power is at least credible. I would expect a KW dissipated in the > tuner to have damaged it, but fortunately that does not seem to have happened. > > The manual strongly recommends setting the exciter radio (my K3) to maximum > power output and trusting the ALC to set the correct drive power. Many here, > including me, will disagree. However, as a result of this recommendation, the > manuel doesn't really address the drive power issue. > > Please note that the antenna is driven through coax and not open wire or > ladder line, so theories based on those feed lines don't apply. > > Thanks to everyone who replied. This list is a wonderful resource. > > 73 Bill AE6JV > >> On 12/27/21 at 2:48 PM, [email protected] (Bill Frantz) wrote: >> >> I didn't have a good night in the K1USN Slow Speed Test. I started >> more-or-less on time and tried to answer CQs. None of the stations I tried >> could hear me. My SPE 1.3K amp said I was putting out about a kilowatt, >> although the antenna tuning on my normally low SWR 40M dipole needed to be >> redone. I was receiving many stations, at normal levels. >> >> After a few minutes, I started searching for causes, since operators calling >> CQ weren't hearing me and sending CQ again. Some of these operators had >> worked other stations, so I knew their radios were basically working. I >> tried maybe a half a dozen stations. >> >> Finally, in desperation, I raised the tune power in my K3 exciter to 15W >> and retuned the dipole yet again. Things started working and I managed to >> check into the Elecraft 40M CW net via KD5ONS in OR at 0050z. With only 5 >> minutes in the contest left, I managed QSOs with W6SX and VE5MX. Thanks to >> both of them. >> >> My current theory about what was happening is that ice on the antenna was >> eating transmit power, although receive seemed normal. Does ice seem a >> reasonable explanation? What else could be the cause? I'd love to come up >> with a believable answer. Even more so, avoid the situation in the future. >> >> 73 Bill AE6JV > > ----------------------------------------------------------------------- > Bill Frantz | When all else fails: | Periwinkle > (408)348-7900 | Voice and CW. | 150 Rivermead Rd #235 > www.pwpconsult.com | | Peterborough, NH 03458 > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
