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Title: Af-68 Bias from M-1070 Post by: NJ2MR on April 04, 2012, 06:44:23 PM What do you guys think of this Bias curcuit
Title: Re: Af-68 Bias from M-1070 Post by: K3ZS on April 05, 2012, 08:35:27 AM Other methods shown for the AF-67 are simpler and do not require an extra power wire. The one I use is to place a 5W/22V Zener in series with the modulator tubes (which are now grounded) and then ground the center tap of the driver transformer. Theoretically this reduces the driving voltage of the modulator but I find with this method, there is still more than enough modulation. Search this board for AF-67 mods. There are other ideas.
Title: Re: Af-68 Bias from M-1070 Post by: K3ZS on April 05, 2012, 10:35:06 AM To clarify, put the zener in series with the modulator tube cathodes, back biased. I also have the zener bypassed, I think around a 0.1 uF cap. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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