I recently modified my Heathkit SB-220 Amplifier to operate on 6
meters.
I used the 10 meter position on the amplifier.
I performed the following actions:
1. Repositioned plate coil tap on 10 meter position to 1 2/3 turns from
C55 Tune capacitor.
2. Changed 10 meter input tank capacitor C35 to 33 pF
3. Removed 10 meter input tank capacitors C33 and C34 and replaced with
one 10 pF
4. Changed 10 meter input tank coil to 2 3/4 turns.
I attempted to see what I could get for output power on 6 meters and
found
no more than about 100 watts with 70 watts input. Some resonance on 6
meters was
found about where the 10 meter position is on the Tune position.
All connections are solid and all part leads were made as short as
possible.
This amplifier has all of the Harbach improvements.
I am wondering what I need to do next. Is it possible that the Harbach
improvements may have compromised
any performance on 6 meters since these modifications were designed for
HF only ?
K7XQ Jeff
Atwater,CA.
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