re
Date: Sat, 25 Apr 2009 22:57:25 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] Fw: High SWR = Baluns actually
To: <philc@texascellnet.com>, "'Amps reflector'" <amps@contesting.com>
Message-ID: <5B0E62CF8E4647DDA21971C5DCC60166@KITTYMA123>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
That phenomena certainly does affect 80-10M amps and National addressed
the problem in 1963 by connecting a 10pf 1kv silver mica directly
across
the 20-40M switch contacts. Ive mentioned that on this and other forums
going back to the 90's.
It also works well on the SB-220, TL-922 and other amps known for
eating
bandswitches.With the 160-10M amps the capacitor is more effective
between 80-40 but dont be afraid to experiment as the way amps handle
the coils varies.
The capacitor is added to the Tune Cmin so 10-15M tuning will change
slightly. In some amps the 10M coil may need a very small stretch.
With 10pf 1kv micas not all that available Ive used 10-12pf ceramic TX
caps rated at 5kv with no problems. A 2kv disc vaporized in a B&W
PT-2500A
Carl
KM1H
=====
very clever, just change the tuning so out of band bad resonance!!
Where were you when I needed that, befoore I became obsolete!!
Now it is all transistor coills, quite different, but similar problems.
K2LB
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