Koert,
The absolute minimum voltage found in the C1 null (as observed at TP4)
is not as important as the depth of the null.
If you cannot achieve a deep and rather sharp null, there is something
wrong with either T4 and its associated components or with your dummy
load. The actual voltage at the null will depend on the power level used.
Assuming your dummy load is good (you can check it with an antenna
analyzer), you should see a 1.0:1 SWR on all bands.
Since you indicate a higher SWR on the low frequency bands, that
suggests that T4 does not have adequate inductance for those bands.
Check that you have used the correct core for T4 - it should be one of
the gray (ferrite) cores and not one of the black (powdered iron)
cores. Be certain that T4 has well stripped leads and is properly
soldered. If you observe toroid solder connections that look a bit like
volcanos, that lead was not well stripped - a good solder connection
will look like a mountain with concave sides - if it has a convex shape,
too much solder was applied and that fact can mask a poor solder
connection - wick away the excess solder and resolder properly.
73,
Don W3FPR
Koert Wilmink wrote:
Dear all,
Please find my emails to Elecraft support below. Is there maybe somebody with
additional tips?
Thanks!!
73 Koert PA1KW
-----------------------------------------------------
Hi Gary,
Sorry for my late response, but I had not the opportunity to work on
this earlier. I moved houses and that took longer than expected.
I did check the HV bias and that is 135volts. The diodes are ok and the
voltage on TP4 2mV on receive and 240mv on transmit (tune).
I did connect a good dummyload close to the KPA100.
I did the re-adjustment of the SWR bridge but this provided me not the
required results. The best results with adjusting C1 on 5 Watts is:
160m 1.8-1
80m 1.3-1
40m 1.0-1
30m 1.0-1
20m 1.0-1
18m 1.0-1
15m 1.0-1
12m 1.0-1
10m 1.0-1
Please help......
Best regards and 73,
Koert Wilmink
PA1KW
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