FL-2100B parasitic choke question

[Crambone]

so my question is about testing a parasitic choke. I was just taking a peak in my FL-2100B and everything looks good as it should the amp is working fine. But one thing I never tested was a parasitic choke so I thought this would be a good opportunity to learn a bit.
Thank you for sharing your knowledge if possible.

 

[Tallman]

That would require an engineering lab and knowledge of all of the design specifications.
Digital memory scopes and at least 3 engineers to work all of the test.

If your unit is working fine you probably do not have a problem.

 

[Shadetree Mechanic]

I think they just keep the tubes from going into oscillation and keeping itself turned on. Someone correct me if I'm wrong.

 

[Tallman]

You are right.

 

[Crambone]

Am I correct in my reading that they limit frequencies at high voltages? Is oscillation caused by the over voltage or excessive frequency? I’m thinking it has to do with the tubes bias and frequency?
Again just trying to learn a bit, thanks for the reply’s

 

[Shadetree Mechanic]

I think it impedes the flow at the frequency that the tube would "ring like a bell" at.

 

[BJ radionut]

Helps block unwanted frequencies outside the tuning range, and yes keeps down oscillation at unwanted frequencies,
Unless they look burnt or resistors look cracked, you are fine.
All the Best
Gary

 

[wavrider]

https://www.w8ji.com/vhf_stability.htm

 

[Crusher]

On a lot of the tube amp stuff, I try to use a Hi Q input circuit. Something like a 5 and sometimes higher (11M) stuff. Won’t do anything for IMD, but it really helps on the harmonics.