It might help to give us some more information (see below):

On Sat, 12 May 2007, Jimmie D wrote:

I am trying to modify a 1 tube amp for 6 meters using a 6146. I think the
amp was origionally used for CB though it does tune up on 10 meters. It
worked OK before I removed the input circuit and put in one for 6M.

A key question I would ask at this point is whether the amp, used
originally for CB (27 mHz), was, itself neutralized? Some ham transmitters
were not neutralized (eg. Heathkit, Ranger) although they were operated up
to 10 meters.

The
problem is I cant neutralize the damn thing.

When you removed the original input circuit, what, exactly, did you
replace it with?

I have found that neutralization of grounded-cathode amplifiers (i.e. high
gain) can be a major pain.

It makes a great osc.I was
thinking of scraping the tuned input and replacing it with a 200 ohm
resistor and a 4:1UNUN. I figure this low of an impedance on the grid would
swamp out any feedback that might me causing it to osc.

Nah, I gonna bet that ain't gonna work.

I have about 5 watts
PEP of drive.

FWIW:
My approach to this would be to build something grounded-grid and that
means any grid tube where you can get all the grids to (real) ground. You
_might_ get 6AG7s or 6CL6s (two might be enough) in parallel and
any decent input matching network might do the job for you and get
about one "S-unit" of power gain. Tube efficiency will be a little lower
at 50 mHz than 27-28 mhz but not that much.

One of the guys said that screen grid bypassing is critical and I can
attest to that, too. Some of the published material even gives separate
neutralization circuits for just the screen grid circuit. Very big pain in
the neck if you have to do this by trial and error.

Good luck!


Jimmie