[Boatanchors] When to use neutralizer capacitor

[Howie WA3MCK]

Hello John,

Here's a unique approach to neutralizing a 6146 that was used by Heathkit
over 50 years ago.

Take a look at a schematic of the Heathkit DX-60 HF Transmitter. All
versions were electrically identical.

Instead of utilizing a variable capacitor a neutralizing stub (length of
stiff wire) was used) and placed in close proximity to the 6146 tube
itself.. Cheap and simple.

A bit of jockeying the wire around and following the instructions in the
manual for neutralization usually always yielded satisfactory results.

I still have several DX-60's.
All functioning perfectly.
All neutralized.
All taking up quite a bit of space.

Have a good weekend John.

We are approaching 100 degrees here in Northeast Pennsylvania.

Howie WA3MCK





On Sat, Jul 22, 2017 at 13:35 John Saxon via Boatanchors <
boatanchors at mailman.qth.net> wrote:

> Excuse my ignorance here, but I am in need of some consulting.
> I would like to build a 6AG7-6146 transmitter.  As I research around I see
> some 6146 PAs that have the neutralizing capacitor and some do not.  So I
> have not been able to figure out when a neutralizing cap must be used.
> I am guessing that the following are possible factors:1. grid-plate
> capacitance of PA tube2. PA on same frequency of OSC, or not3. Whether or
> not there is a tank circuit in the OSC
> So I would appreciate some comments from you gurus out there, or perhaps a
> pointer to a good description.  I have been doing reading, but am still
> confused (not the first time that has happened).
>
> Any and all information greatly appreciated,JohnK5ENQ
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