Hi all,
I`m somewhat surprised / disappointed:
I tested the TX aerial with the ROPEX (157W) and with the homebrew PA (reduced
to 150W).
ROPEX: phase of V and A on the feeder cable OK.
Homebrew: phase of V and A = chaotic (but it works).
see oszilloscope pics.
the feeder is a 90m long koax cable RG213U.
if connecting a 50 Ohm dummy instead of the aerial both TXs show the same in
phase of V and A.
the matching -, loading system in this case is simple:
length of the fixed coil = 208mm, length of the inner variable coil = 110mm.
diameter of the fixed coil from centre to centre of wire = 404mm,
of the variable coil = 364mm.
windings = 30. (Z=50? at 8 windings for 150W LF power and at 7 windings for
800W).
space between centres of neighboring windings (pitch) = 6mm.
the aerial is a 16m vertical with elevated coil 12m high and 270m horizontal
wires.
what is it the homebrew 4 x IRFP450 PA doesn?t like? (LPF between feeder and
output).
regards
Uwe/dj8wx
A and V.JPG
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