>
>> >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.
? The Tune-C series-resonance frequency is Near the oscillation
frequency - but not on it. This is what transforms the Tune-C into a
Z-stepup L network.
>
>> >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?
>
? No.
>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,
? I did not propose this. What makes you think that L-networks have
high input impedance?
>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.
? The Tune-C is being operated *Near* a series resonance.
>All your claims
>about VHF parasitics damaging components are just "arm-waving"
>to sell kits and slam manufacturers.
>
? Manufacturers discredit themselves. For example, Bridgestone /
Firestone apparently knew about the tread separation problem in 1992,
yet they did not fix it. About the same time, I was driving my Dodge
maxivan on the freeway when a sudden tread separation occurred in a
Bridgestone tire. So how did this happen?. In a word, the answer could
be *ringeshow* (pronounced rin-gay-show). Ringeshow is a Japanese word
which means that needed changes can Only come from the Number One (dai
ichi) manager. Any other person in management who suggests that a change
is needed will almost certainly be booted out of the company because he
violated ringeshow by dissing the #1 dude.
Apparently, Ford also knew about the tread separation problem eight or so
years ago, and they did nothing. . . Ringeshow.
At this moment, two 8877s which suddenly failed in an AL-1500 are being
shipped to me. My guess is that gold-sputtering is present in both.
Eimac said that gold-sputtering results from oscillation. If the tests
proves me wrong, all of you will hear it here.
>> >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.
>
? Does anyone who owns a dipmeter know where a grounded 811A grid
resonates?.
>> >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.
>
? I know abundantly well that series-resonance has low Z. PLEASE READ
CAREFULLY
THE TUNE-C IS BEING DRIVEN WITH ENERGY THAT IS *NEAR* THE
SERIES-RESONANCE, Tom.
>> >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.
>
? They can still oscillate. We can't do anything about grid resonance.
Lower Q VHF suppressors are seemingly needed.
>
later, Tom.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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