> From what I have read, this amp seems to be well built with a couple of
> questions. The amp uses a 4 to 1 "transformer" in the output. I guess its
> really a balun. Im not a big fan of baluns so Im a little hesitant about
> this especially using the amp on AM. I wonder why QRO uses this balun.
Your guess is correct, it is an un-un (unbalanced to unbalanced) transformer.
This allowed QRO to omit those costly RF rated padder capacitors on the
low bands, and get away with a lower value C2 in the pi-network. Don't let
the "snake oil" salesmen try to convince you this has any affect on IMD,
harmonics, or anything else....this circuit is equivalent to a strait
Pi-network.
Do not get me wrong, there is nothing wrong with this scheme, it works fine.
It is there for economic reasons, not some revolutionary new "good as a
Pi-L" scheme.
Sorry, I have no Russian experiences with tubes. The QRO amp line has
some nice features and seems to be well-built. I would consult with the
factory and the manual to discuss your operating modes and goals for each.
(((73)))
Phil, K5PC
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