[Kenwood] TS450S rec problem

2003年11月11日 17:05:57 -0600

Two possibilities. The SSB filter has failed (may be a ceramic filter)
or the BFO setting (in the menu I believe) has shifted the BFO into the
filter passband. I think that same filter is used for transmit so you
may be transmitting some LSB also.
I don't think the diodes in the balanced modulator would have any effect
because the balanced modulator and product detector respond equally to
both side bands, its the filter that selects the side band.
Check just exactly what spectrum you hear by tuning past a continuous
carrier, say WWV on 15.0 MHz. When properly set on USB you should hear
tone only with the dial frequency below 15.000000 and the tone should
only have a range from 300 to 2500 Hz give or take. If you hear tone
past zero beat and on the lower side, then how high you hear tone will
hint at how much problem there is. You should also be able to get
amplitudes for plotting the filter response curve that way. 
It could be that the filter switching is switching in the AM filter
instead of the sideband filter, that could be a diode or logic problem,
or operator problem since the TS450 allows a great deal of operator
freedom in filter selection from the front panel. You probably want it
to select filters by mode rather than overriding that. Something to
check also.
73, Jerry, K0CQ
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.