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

[Sherrill Watkins]

Dear Glen: Thank you very much! I was not aware of that terminology for
discussing the grids of tubes and I was first licensed in 1956! I confirmed
that with a friend of mine who is a retired electronics engineer and he said
you are correct!-73- Sherrill W. k4own. 

-----Original Message-----
From: Glen Zook [mailto:gzook at yahoo.com] 
Sent: Wednesday, September 29, 2004 6:27 PM
To: Sherrill Watkins; johnson at mailman.qth.net
Cc: Thomas Bonomo
Subject: Re: Why is the Johnson Viking II final amplifier NOTneutralized?? 


If an external bias is applied to the final amplifier
stage then what you say is definitely true.  The
higher the bias the more drive that it is going to
take.

In the simpler rigs like the DX-35 and DX-40 the grid
is "swamped" by a resistor requiring more grid drive.

When the term "grid" is used it normally does mean the
"control grid".  The screen, supressor, etc., grids
are usually called either by their "first" name
(screen, etc.) or by their complete name (screen
grid).

Glen, K9STH


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

When you say "grid", I presume you mean the CONTROL
grid, that is the grid the closest to the cathode of
the 6146 final amplifier tubes. I noted that the two
control grids of the Valiant II are tied in parallel.
Also, there is a lead from the control grids going
through an RFC choke L6, through a 1600 ohm resistor
R24, through a meter shunt resistor SH4 and then
connects to the negative bias side of the power
supply. The bias voltage at the power supply is
labeled -75 volts. (The Viking II does not have a
resistor that connects the control grids directly to
chassis ground but has negative bias voltage applied
to the control grids.) I do not know what the exact
bias voltage is on the control grids of the two 6146,
but does this have an effect to reduce the gain of the
two 6146 tubes?

=====
Glen, K9STH

Web sites

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


		
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