It's a 600 ohm transformer, rated for 7dBm max (about 1.7
Vrms across 600 ohms).
Bob NW8L
But that doesn't mean it distorts or "saturates". It is
simply a rating.
My K3 for example on a good Agilent selective level meter
starts to distort at -5dB reference to 1 milliwatt into 600
ohms. That's a front panel setting of about 50 on the line
output level adjustment. At -5dB the second harmonic is
down 58 dB (absolute level of -63 dB mW ). At lower
settings it gets better.
While I have not looked inside the radio (and won't bother)
the distortion has all the characteristics of a mismatched
output device because it clips at about the same level
regardless of frequency. If it was that commonly spoke of
but elusive to find "core saturation" the point of
distortion should change with frequency. That's because the
flux level should change with frequency for a constant
voltage across the primary as the reactance changes with
frequency.
When I reduce line output setting to 25 (whatever that
means) the distortion is too close to noise floor to measure
accurately.
I would think -10dB below 1 mW, while a bit low from
commercial standards, is good enough for any properly
adjusted ham radio sound card or audio system. I'm pretty
fussy about things that matter, and I think the audio
distortion shortfall (at least from what measure) is
greatly over rated. It isn't out of line with anything else
I use, and is a lot better than some things I won't use.
This is a sample of one unit, but it looks good to me when
the level is kept about -10 dB 1 mW into 600 ohms. I can't
see a problem in a single tone harmonic distortion test.
73 Tom
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