Hello Jack,

In order to neutralize a triode you must have a balanced grid circuit.
You build the input tank circuit just like you would if you had 2
tubes in push pull but rather than connecting one side of the grid
circuit to a second tube you connect it to your neutralizing
capacitor. The other side of the neutralizing capacitor goes to the
plate of the tube.

A bridge or single ended type grid tank circuit will work with a
tetrode but the triode needs the balanced circuit in order to get
enough feed back.

You could also use a balanced plate circuit like you would use with a
push pull circuit and a single ended or bridge grid circuit but a
balanced grid circuit is usually much easier to do than a balance
plate circuit.

73
Gary K4FMX


On Sat, 17 Feb 2007 13:46:35 -0600, Jack Schmidling
wrote:

I need some help and can not find the answer anywhere.

When neutralizing a triode, how much leakage between grid circuit and
tank circuit is allowed?

I am looking at the output of the final loading cap with a scope and get
a few volts of RF when the NC is nulled. This is with 20 ma grid drive
or about 10W input. The output just tickles the wattmeter on the 30
watt range and rises to about 10w when the NC in moved from the null
position.

Second question: should I see any leakage when the filament is off?

Thanks for your help.

Jack