[Amps] How to drive 6M 8877 with DownEast 50-28 ... IPA?

[Tom Cathey]

Hi All,

I need to come up with a CLEAN 50W-70W IPA to drive my newly built 6 meter
8877.

I have 20W available from a DownEast 50-28 transverter.
An older N4NTA 6M kit using a single MRF-492 (10W to 100W brick) looks
interesting as an IPA, but I understand the 3rd order IMD is only
around -25db?  The 8877 is supposedly around -41db, so this would be a poor
match up.

The problem is that the 6M noise floor is very low and when using directive
arrays, so splatter can be an issue for locals... :-(   I don't know what
the 50-28 transverter IMD output is, but I have a call into them with the
request.

I have even looked at building a small tube amplifier as an IPA, but the IMD
on 6146's, 811A's, etc does not seem better than -25 to 30db either.  Even
my 6M FT-650 is speced at -31db.  It appears hard to get a better driver
combo to match the 8877 specs.

I've also thought of tapping into the 50-28 transverter at a low level where
it is cleanest and amplify that up through several tube stages using
negative RF feedback. But, I do not have a design that would suit the
purpose.

Thought I'd ask here before searching further.

Any ideas?  Thanks!
Tom, K1JJ