>
>
>
>
>
>> Rich says:
>>
>> >? page number?
>>
>> pp439 - 442, 3rd edition
>>
? In my copy the statement about curing a parasitic by adding L to the
"plate" is on page 501. However, Terman also recommends a resistor in
the "plate" lead, near the tube. A parallel L/R combination VHF
parasitic suppressor would seem to fill the bill.
>> >Are you saying that less L in R-sup tunes the anode resonance lower in
freq.?
>>
>> No.
>>
>> >? Are you saying that it is impossible to create a broader resonance
>> >with one capacitor and two inductors that have different amounts of L,
>> >that are not mutually-coupled?
>>
>> Yes, with the proviso that the two inductors have a high enough Q that
>> circuit Q is not degraded. Draw a phasor diagram. Note that my definition
>> of resonance is 'applied volts in phase with applied current', however.
? I have seen the Q-lowering effect of staggered double-resonance on a
dipmeter. It is similar to staggar-tuning an IF transformer to broaden
response / lower Q.
>>
>> >The damped-wave VHF ringing in the anode circuit can not pass through
>> >the lowpass tank.
>>
>> A 10m pi network will give about 80dB attenuation at 200MHz. I can see
>> harmonics - they get through. Or are these 'ringing oscillations' (call
>> them that to avoid confusion - one problem with e-mail is that it is easy
>> to leave out a word inadvertently
? Like leaving out the word "rating"?
> > and then have endless fun clearing up
>> misunderstandings!)
? Indeed. . One should copy-edit one's copy before clicking on the
Send Now button.
>> so far down that they can't be seen? If so, how can they have enough
>> amplitude to flash over bandswitches?
>>
? Bandswitch flashover could not be caused by transient-induced
damped-wave ringing in the anode-circuit because the amplitude is quite
small. In order to arc anything, regeneration of the damped-wave
signal must take place. The mechanism that makes regeneration possible
is the feedback capacitance in the amplifier tube. However, my guess is
that there should be a C-Tune series-resonance somewhere in the vicinity
in order for regeneration to take place. To wit: If C-Tune presented a
low-Z across the VHF region, the net VHF RL on the amplifier tube would
be low and VHF voltage gain would be low. . Murphy said that things
are more complicated than they seem at first.
>>
- later, Peter
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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