[Amps] QRO Balun?

[Michael Tope]

> products?  You are altering my remarks. I NEVER said a transformer has no
> losses...quite the contrary....ALL transformers have losses. I seriously
doubt
> that the QRO transformer has a loss of 1 db @ 1.5 kw output.

Sevick has quite a bit of information in his book "Transmission
Line Transformers". According to Sevick's data, measured
losses for typical 4:1 ferrite baluns appear to run between 0.05
and 0.1 dB. This corresponds to a loss of between 17 and 34
watts at full legal limit. He goes on to discuss power handling
suggesting that for ferrite materials typically used, a 1.5" OD
toroid (or 1/2 diameter rod) is typically sufficient for 1000 - 2000
watts of power handling (see page 9-13).

BTW, if a transmission line transformer design is used (as
described by Sevick), I believe the core doesn't play to much
of a roll in the high frequency response (fields are setup to
cancel). Not sure what QRO is using in their amp, however.
In terms of low frequency response, my own experience
with Iron Powder suggests that a 3 high stack of T-200-2 cores
in a 4:1 configuration will barely warm to the touch when
subjected to c. 1500 watts and very pathological mismatches
on 40, 80, and 160 meters.

73 de Mike,
W4EF........................................................................
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