Many thanks, Don, for your comments. Here's my replies...
Don Wilhelm wrote: > "Bob, > > What have you finished of the Testing and Alignment. If you have not > yet done the PA bias adjustment, your KPA100 will have little or no > output as you describe. " I've done SWR calibration, power calibration, power supply test, fan test, external keying test, PA bias adjustment and power tests <= 11 watts. I've started the 20W power tests and that's where the problems appeared. > > "Actually I had some trouble understanding your exact problem. > Do you mean that you have no KPA100 output on 80 meters, but it is OK > on other bands? Or do you have no hi power output on any band? Or, > do you mean that you have about 11 watts of power anytime the power > request is set above 11 watts? " I have hi-power on 80m only. All the other bands (I don't have 160m) only power up to 11W. Over 11W, K1 latches, but the power then drops to around 1-2 watts. There is no increased bias to the PA finals. > > "It is not 'T sense' - that only controls when the fan comes on." Thanks! I thought it was the control to switch the bias to the PA. > > "If QRP transmit is OK, then likely your Low Pass Filters are good - > check on all bands. " Yes, QRP transmit on all bands is OK. > "If you receive properly when set to 11 watts or higher, then at least > part of the T/R switch is working properly." I'll check that one. > > "Calibrate your wattmeter initially at 9 or 10 watts (you can re-do it > at higher power later), but the wattmeter must work to control the > power of the K2 (and the KPA100). " Yes, I've already done that via R26. > > "If your problem is that you have some power output when the power > request is set above 11 watts, but not the proper amount, then check > the Scaling function of the wattmeter - RP1, R24 and R25 and Q10 and > Q11. During hi power transmit, the drain of Q10 and Q11 should be > near 0 volts and you should have 4 to 6 volts on the gates. " I'll check that one, too. A feature so far is that I only get the correct bias voltage (base of Q4 = 1.51V @20W O/P) on 80m. On all other bands, it stays unchanged at 0.52V when I move from <11W to >=11W (the point where K1 latches). > > "73, > Don W3FPR " 73 Bob MM0RKT _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
