That would make sense that it would fail on the lowest band, Pete.
On 80M, the main choke has the least reactance, and likewise the
shunt bypass C between the two chokes has the most reactance. The
extra choke was probably there to make the RF impedance looking
back towards the meters very high since the L network formed by
the main choke and the bypass C might not provide enough
attenuation on their own.
73 de Mike, W4EF....................
----- Original Message -----
From: "Pete Smith" <n4zr@contesting.com>
To: <amps@contesting.com>
Sent: Sunday, September 01, 2002 6:37 AM
Subject: [Amps] Glitch resistors -- replacing RF choke in SB-220
> Thanks all for the valuable comments. A somewhat related question. A few
> years ago I bought a glitch resistor, from a person no longer on this
> reflector, who said I should substitute it for the small RF choke in the
+B
> line of my SB-220 before the main RF choke. I did so -- it was a very
> convenient fit -- and a few days later lost the meter multiplier resistors
> on the Harbach diode board, in a burn-up event that seemed to be related
to
> something odd occurring at RF on 80 meters. It was, if I recall
correctly,
> the first time I'd had the amp on 80 since adding the glitch R.
>
> I thought that perhaps removing the RF choke allowed RF into the metering
> circuit in some way, so I put it back in. Was this a good hypothesis,
or???
>
> 73, Pete N4ZR
> Sometimes a tower is just a tower
>
>
>
>
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