On Wed, 27 Aug 1997 10:17:53 +0000 w8jitom@postoffice.worldnet.att.net
writes:
>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.
Wouldnt it take pressure from the manufacturers? How many would want to
give up their 6dB smoke screen? Be honest now.
>> 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.
That is simply a copy from Command who claims it is the key to their
superior IMD. They (Command) state that they transform the Rp down to
200 Ohms the conventional way and then use the toroid to get to 50 Ohms
on all bands.
I just dont like the idea of using compressed mud at those power levels.
73...Carl
>
>73, Tom W8JI
>
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