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Re: [RFI] Clean Audio Amplifiers For Amateur Use?

To: "Hare, Ed W1RFI" <w1rfi@arrl.org>
Subject: Re: [RFI] Clean Audio Amplifiers For Amateur Use?
From: Rob Atkinson <ranchorobbo@gmail.com>
Date: Tue, 13 Oct 2020 11:02:49 -0500
List-post: <mailto:rfi@contesting.com>
The problem with solid state is that if the RF field is strong enough,
a cheap analog solid state amp will pick up enough RF on the internal
leads and the transistors will rectify it.  This is especially a
problem with cheap plastic enclosures.  Tubes are less vulnerable to
this even if run unshielded.  As someone else pointed out, tube amps
have output transformers that isolate the speaker leads.   The problem
is solved whether the problem is the amp generating RFI or being
vulnerable to it.  You might not get it all, but bypass caps on the
audio inputs will usually be the death blow.

73

Rob
K5UJ

On Tue, Oct 13, 2020 at 8:25 AM Hare, Ed W1RFI <w1rfi@arrl.org> wrote:
>
> Many of the old solid-state amplifiers also have analog supplies.  The key is 
> -- weight. If it's got iron, it's analog.
>
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