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
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