To: <amps@contesting.com>
>> Date: Sat, 16 May 1998 15:33:04 -0800
>> From: Rich Measures <measures@vc.net>
>> Subject: Re: [AMPS] Re: Parasitics
>> To: amps@contesting.com
>
>> Jon Ogden wrote:
>> >.......
>> >A pi network Tank is a resonant LC circuit consisting of both parallel
>> >and series resonances.
>
>Rich replied:
>
>> The next time you have your amplifier tuned up, shut down, pull the mains
>> plug, couple a dipmeter to the tank L measure the resonant frequency and
>> check f with an electronic counter.
>
>There seem to be a few flaws in that method. The most evident is
>that GDO's "pull" quite a bit.
That's why a knowledgeable operator uses minimal coupling.
>If you do use a GDO and see a dip,
>it still tells you nothing about system impedances or circuit
>voltages.
A dipmeter tells you only where a circuit is resonant.
>The GDO only indicates the frequency at which maximum GDO
>coupling occurs. Nothing more, nothing less.
It seems to me that maximum coupling is dependant on placement. With
minimal coupling, a dipmeter indicates at what frequency a resonant
circuit absorbs energy from the dipmeter's vfo.
>
>Second, one should at least use a receiver WHILE the GDO is coupled
>to the correctly terminated tank. GDO's, by nature of the device,
>pull drastically when coupled to loads.
With minimal coupling the pull is hardly drastic. I couple an electronic
counter to the dipmeter when I need to measure frequency more accurately.
>
>Making measurements is always a good idea, if they are made
>correctly and with care.
>
>73, Tom W8JI
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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