Fw: Re: Fw: Re: [Boatanchors] Tube data

[windy10605 at juno.com]

Yes, I know the important number is S/N ratio which is effected by a
number of sources and parameters. It just seems intuitive (to me anyway)
that more cathode activity would be a potential source. Maybe reducing
filament voltage of the frontend tubes would provide even better results,
especially for those like the 7044 when used in the RF section.

73 Kees K5BCQ



--------- Forwarded message ----------
From: "J. Forster" <jfor at quik.com>
To: windy10605 at juno.com
Cc: boatanchors at mailman.qth.net
Date: Tue, 24 May 2005 11:41:24 -0400
Subject: Re: Fw: Re: [Boatanchors] Tube data
Message-ID: <42934B24.B35C1A8B at quik.com>
References: <20050524.090441.2336.9.windy10605 at juno.com>

windy10605 at juno.com wrote:

> They generally draw more filament current, have larger cathodes, and
emit
> more electrons. Many are designed for "off" and "on" (computer use).
> However I have also heard they are excellent for frontends due to "low
> noise". On the one hand "hot filaments" and "low noise" don't seem to
fit
> together but I've seen several articles using 7044 dual triodes in the
RF
> section.[snip]

The issue is S/N or noise figure, not just noise, and depends on the
dominant
noise mechanism. You have to calculate the various contributions to the
overall
noise.

-John