That works well with the Kenwood hybrids also. I believe I use a 25K pot on my 4 TS-830's (3 drive VHF to microwave transverters and the other is at the amp service bench) but would have to look as it has been a long time. Anyway the idea was to get a smoother adjustment so really isnt critical....just preference.
There should be little IMD difference over a wide bias range with most tubes in good condition. As you go below 100ma you are deeper into Class B and there is a point where the IMD goes up.
I use the Deep Class B for AM linears, especially where the PS is marginal as well as some tubes such as in a Clipperton L. I set the bias for around a 2 dB decrease in IMD3/5/7 using the in line SA via a Bird tap and it is never heard on a busy or noisy band. OTOH the 4X 572B's now show just a little color on voice peaks instead of quite red just from idle current. I do not use any audio processing other than some mods in the various vintage TX to expand the bandwidth and make the most out of an unampliied D-104..
Carl
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----- Original Message -----
From: r norris rkmr15203@... [ham_amplifiers]
To: ham_amplifiers@...
Cc: clark@...
Sent: Sunday, April 14, 2019 6:52 PM
Subject: Re: [ham_amplifiers] Bias Boards
On Apr 14, 2019, at 17:06, Clark Turner clark@... [ham_amplifiers] <ham_amplifiers@...> wrote:
The FT101 has a huge ALC over shoot. If I use the ALC it will smack 1500 watts on the first syllable and then fall to what ever I set ALC at (example), 1000 watts. I need to look into this issue or maybe just ignore it. Nobody seems to be able to tell on the air.
You get the overshoot because the rig has to develop the ALC after keyup.
100k pot, 9 volt battery, plus to ground, neg from pot to ALC jack.
Set power out with pot.
No overshoot, since ¡°ALC¡± voltage is "there" before keyup.
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