...don't do that!
You'll never know what combination will hit resonance in what band without a
network analyzer, especially in a multiband amplifier until it's too late!
The idea of moving the output coupling capacitor and the choke to the 50
Ohms side- let's call it "series feed"- seems a more viable idea.
Alex
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Colin Lamb
Sent: Thursday, February 26, 2009 10:47 PM
To: Edward Swynar; amps@contesting.com
Subject: Re: [Amps] Minimum Value of RF Plate Chokes
"I think that a switchable choke arrangement is a FAR better option to
consider, rather than building a separate, dedicated low-band
amplifier...although if I could ever get my paws on a good 833A, or two, I
just might eat those words!"
Instead of using a switch to switch in the extra choke for 160 meters, what
about using a decoupling system similar to multiband antennas.
At the bottom of the regular choke, use an LC combination that shorts rf to
ground on all bands except 160 meters. Below that, have an additional choke
for 160 meters. On 160 only, both chokes would be in series, because the
bypass at the bottom of the regular choke would be "invisible".
73, Colin K7FM
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