>
>Hi Jeff
>
>> This is a sad day in amateur radio. Here we are in a mail list for the
>> high end of the amateur radio building community and we're reluctant to
>> use a tube that requires bias!? 4-1000's look ok when glowing orange but
>> an 833A is gorgeous with that bright red region in the center of the plate
>> (not anode, plate).
>>
>> jeff
>
>The problem is the tube will have low gain. That's because the gain
>of a grounded grid PA is related to the ratio of output impedance to
>input impedance of the tube.
>
>With it's low-mu construction, the 833 would take a heap of voltage
>swing on the input meaning driving impedance would be high and
>gain would be very low.
>
>It would be OK to grid drive the tube,
? Not in linear service, Mr. Rauch. Medium Mu triodes draw little anode
current unless the grid is driven way positive- and that means
distortion. The only kind of triode that is suitable for grid driven
linear service is the low Mu variety.
> but then stability becomes an
>issue. The IMD also goes up because the heavy negative feedback
>inherent in cathode driven systems (the output is in series and out-
>of-phase with the input) would disappear.
>
>The tube could certainly be used,
Not for linear service.
>but it wouldn't be a good choice
>(especially since they have long leads and are prone to self-
>oscillation at upper HF).
>
smells a bit fishy
>
cheers, Tom
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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