I'm looking at getting my venerable 813's amp to play on 160. Works fine
on 80 -> 20, but I'm thinking I need to increase the plate choke bypass
and the output coupling caps in value.
The plate choke is a Hammond 1515x (.25MH) which hopefully will be OK
(~2.83k @ 1.8mhz). But, is that enough reactance or not?
Both the plate cap and the choke bypass cap are at present .001/5kv WW2
micas. I'm thinking of replacing them with .1/5kv Glass Mike 'ASG
104-5M's. Are these appropriate for what I'm planning? I couldn't find
any info on them -- they live in my junk box, thus the choice.
Finally, I'll need to add more inductance to the pi. The inductor that's
in there now is a nice big mother roller inductor (square copper wire
wound on a ceramic form - about 16uh., horizontally mounted). I was
thinking to add a vertically mounted additional inductance wound on a
piece of 1.5" pvc pipe to make up the needed 'L'. Do I need to worry
about the 'sense' of the winding being the same as the original if they
are mounted in different planes as described?
Thanks for any insight on these questions!
jerome - VA7VV
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