>
>On Tue, 04 Mar 2003 07:32:09 -0500 Zyg Skrobanski <af4mp@mindspring.com>
>writes:
>> >IMD (splatter) is not considered spurious emissions by ICOM. All
>> that tells
>> >you is harmonic suppression.
>>
>> Is the IMD normally measured by using a two-tone test? If so, does
>> the
>> particular frequency of the tones (within a normal audio 3KHz
>> bandwidth)
>> change the IMD, i.e. which two tones would give the worst case
>> reading?
>> --
>> Zyg AF4MP
>> Roswell GA USA
>
>Hi Zyg,
> Yes.
>
> 400 & 1800 Hz are used for the FCC (US) tests.
>
> If moving those frequencies a little changed the IMD, I would suspect
>the SSB generating stages rather than the amplifier.
>
> A pair of CW signals run through a power combiner is a better source
>for testing power amps than any amateur exciter.
I have seen amplifiers which exhibited good IMD performance with the
(constant) 2-tone test, but which had 11 db more IMD when (unconstant)
voice modulation was used.
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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