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Re: [Amps] 813's

Subject: Re: [Amps] 813's
From: Tom Osborne <>
Date: Tue, 22 Dec 2015 09:43:27 -0800
List-post: <">>
Hi Colin

When I was using this amp it didn't have a tuned input.  I was using a
Yeasu FT-102 to drive it and it had the pi-net so didn't bother with the
input tuning.

I had a power transformer out of an old Navy TCM-2 tranmitter and that amp
would put out a KW easily.  Might have to dig it out sometime and see what
I've removed from it over the years :-)  73.

On Tue, Dec 22, 2015 at 6:53 AM, Colin Lamb <> wrote:

> Hello Tom:
> That is not true.  It depends upon whether they are grounded grid or grid
> driven.  Grounded grid is a bit cleaner.  The tube is fine as long as it is
> not pushed beyond reasonable limits.  But, that is the same with any tube.
> Sometimes they are run in grounded grid mode with no tuned circuit in the
> cathode.  That makes them dirtier, because the "flywheel" in the cathode
> adds up to 5 db improvement in the imd results, just the same as for any
> other tube.
> It is still a good tube.
> 73,  Colin  K7FM
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