Dear Friends,
I traded in my FT990 to an FT1000MP recently, and have lots of problems. My
home-made amp does not have a tuned input, and the SWR of the input is far
from good on multiple bands. This results in the autotuner of the "MP" is
running all the time, even if I change the freq by a few Hz.
The amp is made with a russian GS-35 tube (similar to an 8877) and currently
the input "cicrcuit is a single 5000 pF capacitor connecting the input to
the cathode of the tube. I have tried other values, with little or no
result. I have tried to install a 2:1 inpedance xformer, no result.
I have tried to use an external tuner between the rig and amp, but it takes
then three to five minutes to tune everything on changing the bands.
Since it is an older amp, very little space is provided for a tuned input
circuitry.
Does anyone have a guess, how much the input impedance of this tube might
be?
Is there a "magic" method to match it to my "MP" without trying to build in
a 2x9 position Yaxley switch and separate PI circuits for each band? All
this in a 1x2x3 inch space...
Is there another solution for this?
Please E-Mail me direct at bogyo@ph.debrecen.hu
73 Steve HA0DU
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