Vintage Asylum

Eli, I keep reading divergent views for the film cap...

100.36.165.229

gkargreen

In Reply to: RE: KT-600 with film cap power supply suggestions posted by Eli Duttman on December 18, 2014 at 10:20:52

position if using only 1 (or 2). I have read that the film cap should be the first (input) cap, someone else the last cap in the filter, and you are saying somewhere in the middle?

Follow Ups:

RE: Eli, I keep reading divergent views for the film cap... - Michael Samra 16:34:21 12/22/14 (2)
Let me clarify
I stress the film cap in the first stage when you are coming off a rectifier tube. If you are coming off sand diodes,you want a low ESR high ripple current electrolytic such has a 105 degree Panasonic or Nichicon or CDE. You can use a film cap but keep in mind that you usually need a higher value capacitance and that can take up some real-estate in the amp or preamp. Anyway,you can use the film caps downstream even if you use an electrolytic.

"
- RE: Eli, I keep reading divergent views for the film cap... - gkargreen 17:10:19 12/22/14 (1)
  thanks, Michael, so if I am using a tube rectifier, first cap should be film/foil, whereas if it is a sand rectifier, use a 'lytic cap, correct?
  - RE: Eli, I keep reading divergent views for the film cap... - Eli Duttman 18:37:10 12/22/14 (0)
    The generalization is flawed. Consider a choke I/P filter. A large value, low ESR, 'lytic after the I/P choke is fine, regardless of rectifier technology. Remember that per older additions of the ARRL Handbook, LCLC is the way to go. A cap. that feeds small signal tube plates is an excellent candidate for metalized polypropylene film. Save the film and foil parts for signal path duty.
    
    Given the intolerance of vacuum rectifiers to large valued cap. I/P filters, a MKP part as the I/P cap., when vacuum rectification is employed, makes sense. Dielectric absorbtion and other losses have to be minimized. Whatever energy is stored needs to be available.
    
    Eli D.

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors:

Signature Sound

[ Signature Sound Lounge ]