[Kenwood] TL-922A question

Tue Feb 5 23:20:05 EST 2013

On 2/5/2013 8:09 PM, rbig wrote:
> I'm going to replace the resistors in my plate parasitic suppressor kit (RF1/RF2).

Depends on what it has for tubes and how much gain they are running. 
The resistors job is to lower the Q of the suppressor. Too low and it'll 
start sucking up 10m energy.
With a 4CX1500B and 3Kv on the plate I use 3 200 ohm 2W, or maybe they 
were 5W) non inductive resistors across a 1/4" wide and a 1" hairpin 
tacked on the end for a bit more inductance. I'd have to measure it to 
be sure, but it wouldn't be applicable to your setup anyway.
My first try used some carbon films I had on hand. Results were 
spectacular, noisy, and kinda stinky. Apparently they were inductive. I 
purchased a pack of 10 non inductive off flea bay. Worked like a champ.
Oh! For the inductor, I cut a 1/4" wide strip from a copper CPU cooler 
fin. Turned out to be just the right length. It looks very much like 
the suppressor Hsu uses on his FU728F amps. Dimensions might be a bit 
different, but the 4CX1500B is almost identical to the FU728F
I think those tubes have a self resonance that is quite a bit higher 
than the 3-500Z.
I don't know what the 3-500Zs use.
73
Roger (K8RI)
>> * What is the resistor description inside the windings? If they're not sold anymore, what is the new description I can get?
>> * Can the resistor be outside the windings? Or must it be inside the windings?
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