If you short-circuit the grid to the cathode with a number of low inductance
caps ( chip caps? )in a super cathode tetrode amp - is this a good start to
get a parasitic-free linear? Without any supressors?
I ask this, because I see in the april issue 1970 of CQ MAGAZINE such an
amplifier using a 4CX1000A at 3000 anode and 325 screen grid volts. The
article shows the relationship beetween drive power and output and is the
curve very linear up to 1500 watts out where you need 180 watts drive. This
is what a TS 950 ( that I would like to buy now ) produces with low
distorsion ( 48 volt final transistors ). I guess the internal structure of
the tube grid and its leads to the outside world will be resonant at some
high frequency where the tube gain maybe will be not high enough to make the
tube oscillate.
The best thing is if the tube is stable: you never get any grid current -
very essential in a 4CX1000A that has a very low grid dissipation allowed.
I guess you must make this short circuit very broadband? Must be equally
effective on short wave as on VHF/UHF? A number of 0.01 + 0.001 uF silver
micas and chip caps may be needed?
Anybody of you gurus has maybe an opinion?
de Hans SM5KI
----------
>Från: measures <2@vc.net>
>Till: "Tom Rauch" <W8JI@contesting.com>, "i4jmy@iol.it" <i4jmy@iol.it>
>Kopia: "AMPS" <amps@contesting.com>
>Ämne: Re: [AMPS] Network analysis of suppressors
>Datum: tor 2 mar 2000 15.12
>
>
>>
>>> My point in an amplifier is to preserve stability and maximize the gain
>>> (and efficiency) were I need, minimizing instead the amplification were
>>> it's not needed to amplify.
>>>
>>> 73,
>>> Mauri I4JMY
>>
>>My point is exactly the same Mauri.
>
>
>>I can stabilize any amplifier by loading it with losses at every
>>frequency from DC to daylight.
>>
>>A good amplifier guru doesn't add unnecessary loss at the
>>operating frequency. He solves the actual problems, not the
>>imaginary ones.
>>
>Adding roughly 1% loss at 28MHz appears to be the price of a
>VHF-suppression device.. There is no such thing as a free lunch -- even
>for amplifier gurus.
>>
>cheers
>
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