Hi Carl,
> Tnx for reminding me about that little ARRL anamoly.
> The 4CX250 runs anywhere from 25 to 28 3rd depending on what spec sheet
> you read and was not necessarily best case.
I wish the ARRL would go back to the same standard the rest of the
world uses.
> The wording in QST was: "Late in our review process, we discovered that
> our AL-800H had developed a problem that caused IMD products that did not
> seem reasonable for an amplifier of this design". That is all they said
> about it. Damaged toroid maybe?
In a phone conversation, they said IMD deteriorated to the 30 odd dB
range. They measured IMD on 14 MHz, and on that band there are no
toroids in the system.
IF I ever get the amp back I'll let you know what caused the problem,
it could be anything from a poor solder joint to a bad tube.
> QRO also had spectral purity problems that were attributed to the 4:1
> output toroid.
Are you sure? Why does a HF PA have a 4:1 transformer in the tank?
That seems non-conventional.
73, Tom W8JI
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