>
>I was a bit concerned to see Wes' data having a column of N/R for the copper
>suppressor, when there clearly was a resistor built in there. Calculating
>the missing values from L and Q gets a set of numbers consistent with the
>parallel values.
>
>I don't have time to go through thorough analysis, but it seems to me that
>the Q of the suppressor network is only one small part of the overall
>picture, and something of a distraction. I also think that it's unhelpful to
>focus in on it in isolation as a parallel network. The suppressor works in
>series from the anode to the tank circuit, so it's the series equivalent
>that's most useful in visualising what is going on.
>
>Comparing series impedance numbers for the W8JI/109 ohms and the NiCr60/100
>ohms from Wes' table;
>
>the copper version goes from .36 resistive + 7 inductive (112nH) at 10MHz to
>98 resistive + 78 inductive (62nH) at 200MHz.
>
>NiCr goes from .8 resistive + 6.7 inductive (106nH) at 10MHz to 79 resistive
>+ 44 inductive (35nH) at 200MHz.
>
100MHz is a more common freq. of osc.
>You cannot look at the suppressor in isolation - you have to view the whole
>series effect between the anode and the tank circuit.
Good point. Unless C-tune has some VHF resonances, an amplifier probably
won't oscillate. Thanks to Mr. Rauch, we know that they have plenty of
resonances.
> The series inductance
>of the suppressor is going to be in series with the connecting leads between
>the anode and the tank circuit, which will probably be another 50-200nH,
>depending on layout - this will reduce, maybe even swamp, the effect of
>differences in inductance between the suppressors themselves.
>
>In this example, for suppressors which are sort of similar at LF, NiCr
>results in higher series resistance at frequencies up to 120MHz, and lower
>above that.
>
How about a quote from Wes' measurements to prove your point?
>I reckon it's not as easy as it might appear to say whether higher or lower
>is better, but that's another story.
>
Lower VHF Q results in less VHF amplification at the VHF anode-resonance
freq. Lower VHF Q also results in reducing the amplitude of the ringing
voltage that accompanies rapid current changes.
later, Steve
>
>
>--
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>Problems: owner-amps@contesting.com
>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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