22nd May 2017
Hello Manfred,
I await the cores and wire patiently, in the meantime i am wondering
if this transformer could be wound to negate the need for my separate
impedance matching transformer outside, and its associated losses? The
set up is Driver - Amps - Combiner - LPF bank- co-ax to outside -
Impedance matching transformer comprising two FT-240 77 material
stacked toroids in a box, with a separate primary and secondary
winding, each with multiple taps that can be manually selected with
banana plugs and flying leads - Loading coil with internal variometer
( BIG plastic bucket wound externally with 2.5mm insulated wire, with
a variometer inside to load to operating frequency - Top hat loaded
vertical antenna about 20 feet high with a horizontal quad loop of
about 480 feet circumference as capacitive top hat.
The matching transformer outside only has a little impedance matching
to do as I see a fairly close match even without it. Could this extra
loss be negated by winding your combiner transformer design
differently? Now I am running more power the impedance matching
transformer is running quite hot... I did build the impedance matching
transformer as an autotransformer, but I had serious issues with RF
setting the workshop and house alarms off, stopping or slowing my
internet connection, and tripping the house mains panel RCD. When I
changed to a "normal" transformer this immediately stopped. Your and
other comments eagerly awaited, thanks.
On Tuesday, May 16, 2017, you wrote:
> Chris,
> at that low frequency, indeed you can make the individual amps for 100
> ohm and put them in parallel, or for 25 ohm and put them in series.
> There should be no phasing problems, at such a low frequency. But you
> have to make sure that both amplifiers have extremely similar responses,
> in terms of gain curve mainly.
> The advantage of using a combiner is that it isolates one amp from the
> other, so the system is highly tolerant to differences between the
> individual amps, down to the point where one amp module can completely
> fail, and the other will continue limping along. Without a combiner, the
> failure of one module would probably cause the demise of the other too.
<SNIP HUGELY HELPFUL EXPLANATION>
--
Best regards,
Chris mailto:chris@chriswilson.tv
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