On Sep 15, 2005, at 3:21 AM, Tom Rauch wrote:
>> On Sep 12, 2005, at 10:32 PM, Tom Rauch wrote:
>>
>>> The spitting is either a bad part like a bad or burnt
> plate
>>> on a capacitor, misaligned relay contacts (the load
> contact
>>> should mechanically close slightly before the input
> contact)
>>> , or you have it loaded too lightly on 80. Sounds like
> it is
>>> loaded too lightly. Open the load control up more.
>>
>> I resolved the "spitting" problem. After carefully tuning
> up the amp
>> for 80m, using as little loading C as possible to get the
> maximum
>> output, there was no spitting into the dummy load. Then I
> switched it
>> over to my doublet, which is fed through a Murch UT-2000A
> tuner.
>>
>> Then I got the spitting, even though the tuner was tuned
> up for a
>> good match. A little detective work revealed that the
> spitting sound
>> was coming from the tuner, not the amp.
>
> Must be an oscillation in the tuner. Probably the tuner
> needs nichrome!! :-)
Sour grapes?
>
> Seriously, T-network or Pi-tuners (or any other tuner with
> three variable components) can be adjusted for a variety of
> network Q's into a given load impedance...all of which
> transfer energy efficiently and present a low SWR.
True enough, but adjustments that result in more circulating current in
the L will result in more I^2 x R loss and less efficiency.
>
> The lowest possible loaded Q results in the lowest possible
> stress on components and highest efficiency.
Then how can all network Qs transfer energy efficiently?
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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