Sorry, but OE is doing it usual job on attribution. I hope I've made the
sequence of comments clear.
-----Original Message-----
From: measures <2@vc.net>
To: Steve Thompson <rfamps@ic24.net>; AMPS <amps@contesting.com>
To: <amps@contesting.com>
Date: 06 August 2000 19:14
Subject: Re: [AMPS] Suppressors
>>This is not the case. To optimize the staggered resonances effect, one
>>needs equal VHF current in Rsupp and Lsupp.
>>In other words -- An optimal suppressor divides the anode-resonance
>>ringing current between L-supp and R-supp.
>
>Why is it necessary to aim for this specific 'optimum' circumstance.
Because the staggared-resonances are optimal when there are equal
currents through R-supp and L-supp at the VHF anode-resonance freq.
--------------
I can only guess at what you are visualising when you refer to 'staggered
resonances'. It would be interesting to do or see some analysis that shows
the optimisation.
If the current split between resistance and inductance is equal, then Q=1.
Lower Q means more current in the resistor and less in the inductor - is
this better because it's lower, or worse because it's not 1?
>There are two requirements - one is to insert enough resistance to kill any
VHF
>resonance that might cause oscillation,
The resonance can not be killed. It can only be damped with
resistance.
-------------
Fair comment - sloppy use of language on my part.
>the other is to insert sufficiently
>little resistance at the operating frequencies. Any given collection of
>components and layout will have its own particular optimum suppressor
>values, and sometimes nichrome will achieve this better than copper.
>
If one wants to reduce 10m dissipation in R-supp and lower VHF-Q roughly
50%, nichrome is a sound engineering choice. .
---------------
I'm not arguing that it isn't.
>The important point is the VHF Q of the whole anode circuit, and that is
>controlled by the ESR of the suppressor, not the Q of the suppressor.
? On Wes' chart, please see column Rp. VHF amplification is
proportional to the total Rp between the anode and the Tune-C.
Isn't it Rs rather than Rp that counts in a series circuit?
>At 100MHz, Rp in the copper-wire suppressor, was 166-ohms. In the
resistance-wire suppressor, it was 101.7-ohms. . Similarly, VHF Q at
100MHz was 2.2 for the copper-wire suppressor and 1.5 for the
resistance-wire suppressor. The bottom-line is that (VHF) ESR, Q , and
Rp are mathematically linked.
Agreed - it's a matter of which of them is important.
There is a troublesome VHF resonance in an amplifier and I have two
suppressors. Measuring their series equivalent values at the troublesome
frequency, one inserts 30nH and 10 ohms resistance, the other inserts 50nH
and 15 ohms resistance. Which one will dampen the resonance more?
Steve
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