[Johnson] Why is the Johnson Viking II final amplifier NOTneutralized??

[Jim Brannigan]

Thanks Glen,
I was wondering why the Ranger did not have neutralization for the 6146
final. A re-read of the 1964 Handbook is in order.
It has been a difficult (mental) transition from Collins to Viking.
Jim

> 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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