[AMPS] Re: Peak vs True

[Jim Riff]

Ralph,

Thank you for your excellent and logical explanation of the exact problem
that I had experienced.
I was looking for a reason why my new linear did not show much greater
output on SSB than on tune/CW.

It stands to reason that these cores are low cost off the shelf parts and
that they saturate at high peak power; looks like a Bird, or a scope would
be the "True" indicators.

Thanks and 73's,
Jim, K7SC

Ralph McClintock wrote:

> Jim,
>  Just about all SWR bridges made for the ham market use inadequate
> toroidal cores in their coupler circuit. When you run up over around 1
> KW the core starts to saturate. I went through this exact thing with a
> Commander HF-2500 6 or 7 years ago. Using various, Heath, Autek and an
> other one I can't remember, I would get the exact results you describe.
> Switching to a Bird 43 peak reading meter resulted in 1.5KW of CW and
> then 2.3KW of SSB. The explanation turned out to be the toroid core in
> the others was saturating starting at about 1KW. When you got to 1.5KW
> they were useless for peak reading. I have no idea how the new Ameritron
> AWM-30 works. If Tom, W8JI, built it I believe he would do more to make
> sure it was accurate for peak reading than the others above.
>  Hope this helps.
> Ralph     W1ZK    Vermont




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