[Johnson] Why is the Johnson Viking II final amplifier NOT neutralized??

[Glen Zook]

I believe that the Valiant II also utilizes
neutralization!

Now, as for the Viking II:  The Heath DX-100 also does
not utilize neutralization as well as a number of
other transmitters which use one or two of the 6146
family tubes.  First of all, the 6146, 6146A, 8298,
6293, etc., tubes are much more "stable" than the
6146B, 8298A, and other tubes of the "B" family which
are NOT the same as the earlier model tubes although
RCA originally claimed that they were interchangeable.

It is possible to keep from needing to neutralize the
earlier 6146 tubes by "loading down" the grid
circuitry.  That is, by circuitry requiring more grid
drive than necessary if the final amplifier does not
have as much loading (lower value resistor to ground,
etc.).  The Heath DX-35 and DX-40 are good examples of
this.  Because of the lower resistance to ground from
the grid this lowers the absolute gain of the stage
and helps keep the parasitic emissions from happening.

Also, the parasitic chokes in the final plate leads
also help to keep the stage "stable".

If you haven't read the information on the 6146 family
of tubes (article was in Electric Radio a while back)
you can find it on either of the websites that are
listed at the end of this message.

Glen, K9STH


<Sherrill.Watkins at dgs.virginia.gov> wrote:

Gentlemen: I would like an intelligent explanation of
why the Johnson Viking II transmitter final amplifier
is not neutralized?! It uses two 6146 tubes in
parallel and does not incorporate a neutralization
circuit of any kind. On the other hand, the Viking
Valiant transmitter uses three 6146 tubes in parallel
and DOES have a neutralization capacitor? This seems a
bit strange and illogical?? If the Valiant II is go
great a design as I have been led to believe, why are
not the final amplifier tubes neutralized??

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco


		
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