> 1. The band switch has 1.8, 3.5, 7, 14, 21, 28 and all band is working in
> the stock form. The problem I noticed is on the 3,5 Mhz. While the the
> phone band is 3.8 Mhz, I tuned the the AMP to work on 3.830. While the
> plate position in the max output power, it generate lots of distortion on
> SSB mode. When I turn down the plate (decreasing the power) the distortion
> disappear. When I used it on 3.5 MHz this problem disappear! Is it the
> problem of the AMP or the antenna (my dipole is resonant on 3.7-3.8)?
You could have RF feedback, caused by common mode current on
the feedline or poor station grounding or lead routing. The antenna
might be too close to the operating position for the RF immunity of
your equipment. Reducing output could reduce gain enough to stop
the distortion caused by RF feedback.
Another possible cause of distortion would be if you do not have
the loading control open far enough.
> 2. Is is possible to use this amp on FM mode? For how long it is save to
> talk ? ( I always use FM mode when tuning this AMP)
What does the manual tell you? FM would be the same as RTTY or FSK rating and
operation.
> 3. On 10m, with 90 watts FM input, I read 900 Watts (on MFJ-989C meter)
> and 700 watts on TL-929 meter. The Ip=600 mA, Ig=260mA, HV=2.1kV. The
> input Voltage is 217.8V and drop to 194V on key-down. Is it considered in
> the normal condition?
The MFJ-989C meter is all over the place. It will typically be as
much as 20% high or low on carrier. It is no good at all on SSB for
reading peak power.
You have a lot of input voltage drop. You can NOT measure the line
on an RMS meter, and see the real voltage drop when the load has
high peak power demand at sinewave crest.
You need to measure the line on a peak reading meter to see the
full effect of poor line regulation when the supply is capacitor input.
It will always be worse than the RMS meter makes it seem.
73, Tom W8JI
w8ji@contesting.com
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