>
>
>--- 2 <2@vc.net> wrote:
>
>> >I have a 1KD-5 that I've been told has been
>> >distorting. The symptoms described lead me to
>> >thinking there was a PS problem.
>>
>> A single 3-500Z will distort when driven by more
>> than c. 65w at this
>> anode V. A workaround is to add some R in series
>> with the cathode drive
>> coupling capacitor to develop RF-negative feedback.
>> For 100w drive it
>> takes c. 25-ohms.
>
>I didn't think that I was driving it even that hard...
>but will double check.... and be sure to keep it below
>the 65W level. It seems to me that if I get too much
>higher than that, Ig gets too high anyway.
>
The 3-500Z is difficult to damage from excessive grid current because it
has a grid that can be run at red-heat for brief periods without a
problem. My guess is that the grid contains molybdenum. Tune for max
RF out with c. 65w drive and grid-current will be good.
>>... ...
>I didn't realize that these were diode stacks. I
>guess I thought of them as a single ( or in this case
>double ) diode device. TNX
>
ur welcome.
>> Your 3-500Z may be distorting because it is running
>> out of emission due
>> to the use of c. 5.8v on the approx. 4.8v filament.
>> When a 1KD-5 is
>> operated in Japan, where they have 200v mains, the
>> filament v. is ideal.
>
>Interesting. This possibility I never considered,
>since I was able to get good output ( 600 watts or so
>) with reasonable drive. Since I don't know what the
>orignal transformer supplied, I can't say first hand
>what the conditions were before I got the amp.
>
With a stock amp., it is helpful to have a free supply of new tubes.
>> Typical emissive life in the U.S. is c. 200-hours in
>> a stock 1KD-5. Does
>> Henry Radio sell replacement tubes?
>
>I don't know. The should maybe furnish them gratis if
>they designed the amp so that it operates outside of
>the tube manufacturer's specs. :-)
>
Very funny.
>Actually, I hope to have my 4x813 project amp running
>soon and won't need to bother with this any further.
>Are you available for on-air testing? :-)
>
Yes
>Thanks much for your time and thoughts
>
ur welcome, Randy
cheers
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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