[Heathkit] DX-100B on Phone - bad audio distortion /oscillation

[Carl]

Matching is the preferred method for parallel tubes particularly in linear 
service where the idle current contributes a lot of heat.
In Class C its of less concern as long as both tubes have similar emission. 
This can be done by removing one tube and recording the output power. 
Remember to keep grid current to 2.5ma or less.

Carl
KM1H



----- Original Message ----- 
From: "Bill Cromwell" <wrcromwell at gmail.com>
To: <heathkit at mailman.qth.net>
Sent: Friday, December 02, 2011 12:31 PM
Subject: Re: [Heathkit] DX-100B on Phone - bad audio distortion /oscillation


> Hi Rick,
>
> I don't believe a matched pair is necessary for paralleled tubes. The
> DX-100(B) finals are in parallel. "Matching" might help with tubes that
> are used in push-pull but the matching methods used by some of the
> dealers is of dubious value. Grab any old pair of 6146's.
>
> 73,
>
> Bill  KU8H
>
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