[AMPS] 811 GG tuned input?

[João Kolar De Marco]

Hi to you all!

I´m new to the reflector and I´m seeking for advice, opinion and hints
on the following:

I own an old amp based on four grounded grid 811 tubes. One of them went
dead so I believe it´s time to look at it before installing the quad set
a friend brought from the US (from RF Parts).

The input to the cathodes is untuned. I know the amp was designed for AM
use. Would it increase linearity by an usable margin to include pi
networks on the input? (I only operate CW and SSB). I would probably
have to build the pi filters on a separate box with another band switch
or add a wafer to the existing one and a bunch of relays . Also, the amp
has some neutralization, a small variable capacitor between the plates
and a link made of few turns over one of the cathode chokes. Is this
really necessary? The amp tunes the 5 pre WARC bands; what may I expect
from it on the new 3 using the closest frequency band switch position?
How about either adding 160 or 6 meter coverage?

The HT is about 1500 V under full load. Any further ideas on
improvements?

I thank your time

73

Joao Kolar De Marco, PY2FCE



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