Well, back home again after some 136kHz tests this weekend.
Several unexpected problems showed up, so there's still work to do on the
station.
I wasn't able to put my new transmitter with 4xIRFP450 on the air.
It did work prefectly on a 50Ohm dummy load, but with the antenna connected
I just couldn't get it
into the air.
The SWR protection continiously came in, even when reducing the drainvoltage
to 40 Volts.
I tried to re-adjust the SWR protection circuit, but that didn't help
either.
I once get some power out for a fraction of a second, just enough to see a
flash over some-where
in the ouput filter.
I had to run the good old 2xIRFP260 transmitter (G0MRF) and that one did
work excellent.
No problem at all to run 60V/9A input, producing over 1 Amp antenna current.
However, after long and desperate CQ-calls the first transformer (a large
50mm ring core) that matches
the 50 Ohm coax upto around 150-200 Ohm got really hot............
That means ....... losses.......
I also lost my LF SWR bridge.......due to loss of the diodes, I think.
Despite this I managed to make 1 QSO by incidence.
It was yesterday afternoon, when after some tests I was talking with some
people standing around the station.
Suddenly I heard someone tuning up on my receiver, which was still with its
speaker on in the background.
I immidiatly ran to the receiver, searching for the one tuning.
It was Mal, G3KEV CQ-ing!
I had to call hime once, and the was was made!
In front of several fellow hams, and a TV-camera from someone making a video
film
about HAM radio.
So, dispite all at least an QSO completed.
Now, I have to figure out what went wrong, and how to solve this.
Somehow the number of turns in the output circuit of the TX is not
right.........
I think I wasn't able to reduce the power produced by the 4 FET unit, enough
to get
it out of the protection area.
This weekend raised also the question, if I should go on with the
preparations for
the LX/PA6Z expedition, because of the fact that I didn't hear anybody else
except Mal...............
and some QRSS station on 136.3......
Well thanks all for listening, and calling (if there was somebody calling,
hi....)
Maybe WX was too nice to operate.....
I will keep you all informed about further activeties.
73
Dick, PA4VHF/p from JO32EE
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