> >You must be using a new definition of resonance. Can you tell me
> >what you mean?
> >
> zzzzz
Sounds like you have outgassed. You need to take more nichrome.
> >This is a series-resonance, not L-network, and it is shunting the
> >path the tube must drive on VHF.
> >
> L-networks transform Z. They shunt not.
Nice diversion, but it is not an L network at work. It is a series
resonance.
> >If the tank could freely pass harmonics, or step up the voltage at
> >VHF to high levels, the amplifier would be a TVI nightmare.
> >
> If the tank were a high-pass Pi, VHF parasitic oscillation would be
> unlikely.
So you are saying an amplifying device driving a high load
impedance, all other things equal, is more stable than an
amplifying device driving a low impedance?
You can do better than that Rich, you are arguing against your own
sales pitch!
If the network looked like a high impedance as you "propose"
above, instead of a short circuit, the amount of ESR used to
dampen the anode would have to be greatly increased. Any series
resistance would be a smaller part of the overall system
impedance, and for a given resistance Q would be reduced less.
The tank is typically a virtual short for VHF and UHF energy,
because it has a capacitor shunting the input. All your claims
about VHF parasitics damaging components are just "arm-waving"
to sell kits and slam manufacturers.
> >The impedance of the capacitor is highest at dc, and is reduced as
> >frequency is increased. That's why the tank is a low-pass network.
> >
> >If the parasitic is NEAR the fundamental frequency, or lower than
> >the fundamental frequency, it could indeed arc the tank
> >components over...maybe.
> >
> At the HF/MF fundamental freq. there is not enough feedback C to sustain
> oscillation.
That isn't always true, especially with tubes like 811A's and 572's
or tubes that don't have the grids correctly grounded.
> >Nice try. Now we have single frequency parasitics exactly on 120
> >MHz, where the tuning capacitor has about ten ohms of reactance,
> >driving the tank capacitor with thousands of volts.
> >
> Mr. Rauch conveniently disappears the series-resonance in the Tune C to
> support his agenda.
Mr. Measures fails to understand series resonances have lowest
impedance, and less impedance than either "component" alone, to
support his nichrome sales.
> >What happen to your claim about grid resonance at 80 MHz, did it
> >move in this application to fit your needs?
>
> no. The tubes can oscillate above grid resonance.
Interesting. First they do, then they don't. Nice arm waving.
73, Tom W8JI
w8ji@contesting.com
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