[Moon-net] Help with Plisch cavity

[EA2LU Jorge Daglio]

Hello all,
After some months on stand by, again, I´am working on the 23cm
project, Dish has AZ-EL motors ready and feed support on place.
But, PA still not work, I got a surplus German Plisch cavity and
made mechanical modifications as OE9PMJ scheme.
Then with the output piston at 50mm from bottom end of the old cavity
I test it putting small amount of RF and SWR meter, cathode easily tune
to got 1:1 SWR , but anode is hard to get less than 2:1 SWR.
In "hot" conditions I can get only 100W but at very high plate current,
it seems that the output is not OK.
EA3DXU advice me that is probably the outptut piston is not in the right
place...Then today I move it directly where the otuput was on the original
place, very close to the top of the cavity.
Now in "cold" test I found 1:1 SWR but with the piston is extremely close to
the catode line......
Anybody know where the correct place is for the output piston??
It would be great appreciate, before I start to make new holes to the cavity
like a "gruyere" cheese!
Thanks you in advance.
73
Jorge
EA2LU