Home Tube DIY Asylum

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

5R4GY and filter cap values


I've gotten various amounts of conflicting information regarding filter cap values with the 5r4gy and am seeking advice.

I have a pair of amps that currently uses a 5y3 as its rectifier,first input cap is 47uf. I had one die last night and while digging through a box of tubes (as my entire backup supply I usually use is missing) I was happy to find 11 spare 5y3 tubes.

But I also came across some 5r4gy tubes in a ST envelope. They just looked obscenely large and kind of screamed vintage. I decided I had to try and run them if possible.

All the specs look ok, filament is the same as a 5y3...the biggest difference is voltage drop...but I'd be willing to give them a chance anyway.

The problem is datasheets list 4uf as..at least the recommended cap value. Some have said thats a 1948 value and that later books listed this as 20uf. Many have said don't go over 4uf...just as many seem to have said they use a 5r4gy with 47uf (or more) with no problems.

I've gathered one of three things will happen if I slap these in: they'll just work, they will be fine at first but prematurely fail, they'll start arcing internally. Of those three...I think the arcing is the most fatal but only to the tube.

Thanks in advance.

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

Topic - 5R4GY and filter cap values - DewDude 07:49:04 03/21/17 (14)


Post a Message!

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