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: It will be rather "El Costoso"

Posted by Eli Duttman on March 12, 2017 at 23:24:06:
I already have the quartet of #46s on hand. :>D I've got nice sockets too. ;>)
I have a custom filament trafo on order from Heyboer, which is not particularly expensive. The main power trafo is a stock AnTek toroid, which (again) is not a "big ticket" item and already on hand.
The PP O/P "iron" needed is simple. 3.5 Kohms end to end, without UL taps. I'm going to go for at least 35 W. power handling. An "El Cheapo" uses "textbook" GNFB that includes the O/P trafo and that requires power handling capability above the power O/P. Core saturation due to a LF error correction signal SUCKS. Stability is pretty much a non-issue, as the only caps. in the signal path are between the LTP and driver FETs.
As for Class "B2", the #46 contains 2 grids, but is always used as a triode. Tie g2 to the plate and the #46 is much like the #45. OTOH, tie g1 and g2 together and the tube is nearly cut off, with 0 VDC of bias. Look at the data sheet. A near Class "B2" operating point (slightly positive bias) to tame notching/crossover trouble is pretty (IMO) obvious, with 15+ WPC power O/P not being a stretch in the slightest.