ORIGINAL MESSAGE: <snip> REPLY: I've thought about duty cycles a lot over the years. I believe the highest duty cycle in normal ham operations is a string of unanswered CQs during a RTTY contest. In
ORIGINAL MESSAGE: REPLY: CW by its nature is an intermittent carrier whereas RTTY is 100%. Therefore, if one is for example, ragchewing, where you talk half the time and the other guy talks half the
ORIGINAL MESSAGE: REPLY: As I recall, the AL-1200 dumps the exhaust air from the tube into the box, as opposed to ducting it 100% outside. Adding some duct work would help. 73, Bill W6WRT ___________
ORIGINAL MESSAGE: REPLY: Was your 30 minute CQ test CW or RTTY? Antenna was a dipole with SWR no more than 2:1. I never operate with SWR higher than that. 73, Bill W6WRT _____________________________
REPLY: I don't recall exactly, except that I was lining in Seattle at the time, which never gets very hot. At 80 degrees, the natives start dropping like flies. :-) 73, Bill W6WRT __________________
ORIGINAL MESSAGE: REPLY: If you're happy with the AL-1200, stay with it. When run conservatively as you do, it is a great amp. I especially miss the fast warm up. My current homebrew amp takes 90 sec
ORIGINAL MESSAGE: REPLY: Very good. Nearly all triodes have higher gain with higher anode voltage. Above a minimum V, tetrodes and pentodes generally do not, as the curves show. 73, Bill W6WRT ______
ORIGINAL MESSAGE: REPLY: Correct. If you transmit for 24 hours straight and listen for 24 hours straight, that would not really count as a 50% duty cycle, would it? :-) No doubt the IEEE has a more s
ORIGINAL MESSAGE: REPLY: The 3-500Z cathode current limit is 400 Ma or 800 mA for two tubes. The 3-500Z will work at 2 kV on the plate but it is happier with more. At 3 kV and 800 ma you have 2400 wa
Kevin, I would strongly recommend not trying to finesse blower specs too closely. There are too many variables and you could end up damaging the tube with what appears to be adequate air flow. As the
ORIGINAL MESSAGE: REPLY: I don't have a dummy load like that either. I test using a real antenna on the higher bands in the middle of the night and on the lower bands in the middle of the day. Perfec
ORIGINAL MESSAGE: REPLY: Excellent idea, if the components are available. I have used a temperature gun directly and it works great, if one can access the seals while the amp is operating. RF makes i
ORIGINAL MESSAGE: REPLY: Harbor Freight is a good source for low cost non-contact thermometers. http://search.harborfreight.com/cpisearch/web/search.do?keyword=thermometer&Submit=Go I have one of the
ORIGINAL MESSAGE: REPLY: I don't have data on the 77, but two other Alphas I have owned, a 91b and an 89, both had exhaust temps that stabilized around 190 F after prolonged brick on the key TX. I su
ORIGINAL MESSAGE: REPLY: Newark. 73, Bill W6WRT _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
ORIGINAL MESSAGE: REPLY: I have eight or nine in my 1500 watt amp. All excellent so far. 73, Bill W6WRT _______________________________________________ Amps mailing list Amps@contesting.com http://li
ORIGINAL MESSAGE: REPLY: Need more information. What RF are you switching? The RF to the antenna or the RF in the tank circuit? If the antenna, what impedance - 50 ohms or what? Or something else? 73
ORIGINAL MESSAGE: REPLY: Almost always, SWR bridges use germanium diodes such as the 1N34 because they have a lower turn-on voltage than silicon types. I don't own one of those amps so don't take thi
ORIGINAL MESSAGE: REPLY: Excellent find, thanks! 73, Bill W6WRT _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
ORIGINAL MESSAGE: REPLY: I have never understood why people did this. If you want a triode, get a triode. I guess if you have a tetrode lying around taking up space but you really want a triode it ma