>
>
>----- Original Message -----
>From: Lamb <k7fm@teleport.com>
>To: <k5ra@mail.pulse.net>
>Sent: Wednesday, December 22, 1999 9:11 PM
>Subject: Re: Two Tone Tests
>
>
>> I agree that 2 tone tests are not conclusive. But, I only stated that:
>>
>> "Once you argue that the cause for distortion is excessive grid current,
>> then you must accept succesful plots of 2 tone tests as proof that
>> either the G2DAF circuitry does not have excessive grid current or that
>> it does not matter."
>>
>> If the G2DAF can pass a 2 tone imd test, it does not prove that it does not
>> have intermod. or that it does not splatter. However, it has been argued
>> that the G2DAF circuit has so much grid current that it cannot be linear,
>> and the worst case would be at full drive during a 2 tone test. Passing the
>> 2 tone test would simply prove that the G2DAF circuit does not develop
>> "too" much grid current to be linear. It can be non-linear for other
>> reasons - but not excessive grid current.
>>
>> In this case, the 2 tone test would simply disprove something. And,
>> sometimes knowledge is obtained by eliminating falsehoods and concentrating
>> on the facts.
>>
? The question is How Much grid-current? 0.5Ma of grid-current is a
whole nuther ballgame than 15mA of grid-current. . When I was measuring
on-the-air distortion of the two, DAF amplifiers, I observed that
distortion level changed according to how much grid current was present.
More grid current produced more power but it also made more doo-doo. //
In my opinion, two reasons for DAF distortion during voice operation are
grid-current and the effect of the 3/2-power law (screen potential
unregulation) . During a two-tone test (where screen potential is
constant) low grid-current can produce an acceptable distortion level. .
High grid-current won't.
- For me, the DAF experience proved to be a valuable primer to gaining
an understanding of how religious cults use reinforcement of denial to
maintain control of members. In effect, for a year or so, California had
two well-known hams who had been sucked into the DAF cult. It was a
virtual excursion on the long river in the Land of Pharoahs.
later, Colin
- Rich..., 805.386.3734, www.vcnet.com/measures.
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|