Chris, interesting comments about the ferrite core balun....I bought the
Force 12 balun (made my someone else) and was please with the results.
However, one day when I forgot to engage my brain before putting hands into
motion I tried very unsuccessfully to pump 1kw into my C3e and balun on 40
meters.....unfortunately, not paying any attention to what was the real
problem, I tried several times until finally the amp started to arc over
which it never, ever had done before. Then I looked at what I had
done....long story short, the balun said I had enough of this bonehead in
the shack and fried its little core!
Since I've gone to the 12-turn coax and avoided trying to tune up on
40meters on the C3 and all working great again!
73.../k6sdw
>From: Chris Burger <ChrisB@prism.co.za>
>I have no dedicated WARC antennas, except a pseudo-vertical on 10 MHz (used
>aluminium that was too soft!). Here are my findings; nothing measured or
>concrete, just that "it works".
>
>I force-feed the C3 on 12 and 17, and also occasionally on 30. It's
>mounted
>at about 17 m (50'). SWR is around 4:1, 1,8:1 and 3:1 respectively.
>There's very little F/B on 12 and 30, but probably around 10 dB on 17. I
>normally use the amplifier (2 x 3-500Z, GG) as an Active Antenna Tuner, and
>make sure that the grid current is in limits.
>
>It works well enough. Comparisons with a Cushcraft A3WS showed little
>difference on 12 and 17. It is several dB worse than the vertical on 30,
>although it sometimes hears better (polarisation, I guess). I've never had
>a situation when it was a better transmit antenna than the vertical on 30.
>
>Given that I'm a contester, and only occasionally play some DX on the WARC
>bands, it does everything I need on the WARC bands. I have an average of
>over 250 countries on each band, with very limited operating.
>
>One caveat: With the severe mismatches that you'll see, you need to think
>carefully about the choice of balun. If you use a ferrite core
>transformer,
>you will come to grief. I use a simple coax choke (about a dozen turns of
>RG213), and it hasn't failed in almost five years of usage. A friend used
>a
>commercial balun with his C3, and blew it up in short order.
>
>Short version: It works, if you can handle the SWR and you don't use a
>fancy balun.
>
>Chris R. Burger
>ZS6EZ
>
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>
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