I replaced the transformer in my Swan Mark 1 with a
new one built by Heyboer transformers. I had them
increase the wire gauge in the HV and Filament
windings by one size. Other than that it is the same.
The amp has a voltage doubler in it with about
1500vdc keyed in the CW mode and about 2500vdc keyed
in the SSB mode. I noticed I now have a higher plate
current than I had before(this is a zero bias amp
using two 3-400Z tubes in grounded grid).
Resting Plate Current Before:
80ma at 1500vdc
180ma at 2500vdc
Now it is:
200ma at 1500vdc
400ma at 2500vdc
The plate voltage is the same as it was before. Do I
now need bias?
By the way with the old transfomer I got 1000 watts
key down now I get 1300 watts key down.
73,
Bill
=====
Bill Smith KO4NR
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