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Has anyone ever tried an Auto-ATU as a Tuned Input on a 2879 type amp?


Active Member
Mar 6, 2020
New York
ATU-100 HF Auto-Tuner boards assembled for $40?
Price on these ATU boards keeps dropping. Assembled boards, not just the kits.

I'm interested in trying to use one as a Tuned Input. Say ..... a cheap 4-pill type amp that I may have laying around.
The MRF422 amp works great w/ a small manual ATU between rig & amp -sometimes I can't how good believe- but it's a pia to use.
Anyone ever try using an ATU for a Tuned Input on say a 2879 amp?

neil, NYC
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Consider that an amplifier's input-matching circuit may also provide stability, reducing a tendency to oscillate by 'swamping', or providing a low impedance path to ground for stray positive feedback that can appear on the amplifier's input.

Some RM Italy amplifiers get downright happy, oscillating if the connections to the input attenuator "drive level" selector come loose.

And your amplifier may not care at all. Swamping resistors will take care of this circuit function sometimes.

I think I understand: The efficiency of swamping makes an auto tuner impractical. My bad, I keep trying to re-invent the wheel.

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