Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

RE: Choke loaded CF

Posted by Triode_Kingdom on March 7, 2017 at 08:14:19:
As a general rule, the inductive reactance needs to be five to 10 times the operating impedance of the circuit at the lowest frequency of interest. In the case of a CF, operating impedance is determined by the output Z of the tube. As an example, if the output Z of the tube is 300 ohms, XL should be roughly 3K ohms at 20 Hz. That can be accomplished with a 25H choke. In addition to plate chokes, it's possible to use the primary of inexpensive SE transformers for this. You only need to ascertain the inductance of the winding. As for the total resistance needed to bias the circuit, bypass the cold end of the choke to ground with a good quality capacitor, then add enough resistance in series with the cold end of the choke to equal the desired value.