I am a new member of the amateur radio community, and my first HF rig is an
Omni C. I was attempting to tune an antenna with a MFJ949E, with the mode
select switch (SSB-R / SSB-N / CW / LOCK) switch in the LOCK position, and
DRIVE set just high enough to allow tuning.
Suddenly the antenna tuner needles dropped to zero, and it appears I no
longer have RF output. The Model 255 power supply did not shut down, and
the receiver is still functioning. I am assuming that I managed to blow the
MRF458 output transistors due to doing _something_ wrong. Maybe just a
matter of fiddling too long and letting things get too hot. I don't know.
Measuring the MRF458 with a meter suggests they might be bad, but it isn't
a case of a dead short, and in the past I've found that power transistors
can be deceiving when doing an in-circuit test.
So... I looked for any sign of a fusible link or other protective circuit
in the Omni schematics and didn't see any, but I thought I'd ask the
experts before pressing "sumbit" on a transistor order.
And any hints tips corrections to keep me from repeating my bungle would
also be appreciated.
Much thanks,
Paul
AC8OI
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