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1. [Amps] hf-2500 again (score: 1): Author: "K1TTT" <K1TTT@ARRL.NET>; Date: Sat, 20 Apr 2013 14:33:08 +0000; Ok, got parts in and replaced most of the bias circuit. Now I have 9.7v on the cathode on rx and 8.7v on tx. Would those be reasonable for bias when cutoff and tx in ab2 operation for the pair of 3cx; /archives//html/Amps/2013-04/msg00182.html (6,884 bytes)
2. Re: [Amps] hf-2500 again (score: 1): Author: TexasRF@aol.com; Date: Sat, 20 Apr 2013 11:45:36 -0400 (EDT); David, it sounds like the cutoff bias is not operational. Most amplifiers have a resistor in series with the zener bias that develops cutoff bias when in standby. Then a relay or solid state switch s; /archives//html/Amps/2013-04/msg00183.html (7,907 bytes)
3. Re: [Amps] hf-2500 again (score: 1): Author: "K1TTT" <K1TTT@ARRL.NET>; Date: Sat, 20 Apr 2013 16:41:07 +0000; That is essentially correct on how this one works. I did replace the transistor that shorts out the 330k resistor and that seems to be working now, the last thing I found was a capacitor across that; /archives//html/Amps/2013-04/msg00184.html (9,116 bytes)
4. Re: [Amps] hf-2500 again (score: 1): Author: "K1TTT" <K1TTT@ARRL.NET>; Date: Sun, 21 Apr 2013 13:48:21 +0000; Another advantage of having more than one of these. besides not being in a rush to fix it, is that I can put another one side by side and compare measurements. Yes, the cutoff bias is too low. A good; /archives//html/Amps/2013-04/msg00186.html (10,564 bytes)

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