[AMPS] G2DAF Circuit

[measures]

>
>Radio WC6W wrote:
>>
>>
>>On Thu, 26 Oct 2000 21:24:20 +0200 Peter Sundberg <sm2cew@telia.com>
>>writes:
>
>>>But maybe we should start testing other amps than DAF's without using
>>the
>>>two tone test. A poorly regulated screen power supply in a grid driven
>>amp
>>>should maintain a pretty stable voltage with a two tone constant
>>modulation
>>>not giving away that the amp would sound bad when modulated by speech. 
>>>True or not .. ?
>>
>>    IMD testing using white noise is possibly a more accurate methodology
>>and more representative of a real world voice situation.  A good
>>description of the technique may be found in "Single Sideband, Systems &
>>Circuits" by Sabin & Schoenike, 1987  pp 473-477.  
>
>The problem with the white noise test is that, like the two-tone test,
>it does not test the effect of variations at the word or syllable rate.
>If the only test is at high frequencies, the capacitors in the HV and
>bias supplies will maintain constant voltages - but if tested with real
>speech, the voltages swing all over the place.
>
good point
>>
>>   Here in the states, I believe that the FCC still uses the two tone
>>standard for their distortion tests so, it makes sense that if that is
>>the test you need to pass, that is the test you run.
>>
>If it is the only test, you learn the truth but not the whole truth.
>
The FCC does not bring distortion measuring instruments to station 
inspections.  The FCC couldn't care less about distortion that is Inside 
the amateur band in use.  
>>
>>   It may be have been forgotten by now... but, when I got entangled in
>>this thread 24 hours ago, I specifically stated that I am NOT an advocate
>>for the DAF concept.   I just like to see the facts & numbers kept neat! 
>
>My position also - neither for nor against, but very much on the side of
>open-minded discussion.
>
My position is to make a total imd measurement 3.6KHz from the carrier 
freq.  To do this, I use two double-filter radios.  Next, I ask if the 
operator is interested in the result. 

cheers 

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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