I have heard that you should not replace 5y3 with 5y3G or 5y3GTA/B. As long as the radio does not use series filaments would it matter which type you use?

Corbymite

The only difference between 5y3g and 5y3gt is the style of the glass bulb. If space permits, you can interchange them.
The ones with the ending suffix a/b usually indicate performance measurements (better quality) as in the case with 5y3gtb, it was used in aircraft computer equipment.

I don't believe there is a 5y3 metal type. If there is a metal-type tube, I hear that you have to ground the shell i think, at least they have a pin going to the shell in most cases.

5Y3 were not used in series sets, it's heater has to be powered from a separate transformer winding, it has the same electrical specs as the big pin type 80...

There have been rumors of a metal 5Y3, but I doubt they exist as least as a regular production type, a metal version was never registered with RMA/EIA...

Tom

A 5Y3 was registered 6-6-35 which would have indicated metal, actual production unknown.

Carl

There is a 5Y3 listed in Tube Lore, and a 5Y3 in the RMA/EIA registrations but it's listed with a ST14 bulb, also lists 5Z4 as metal replacement... In the master index(where I first checked), Jim Cross lists the 6-6-35 registration as 5Y3G...

Tom

Matters almost not. Later GT or GTA/B might be a little beefier, but for old radios it does not matter.

Thanks for all the replies!

Pretty much what I hoped, "if you have it use it"

Corby

I tend to go with Lud for reliable info.

Not discounting Lud's work, but I'm looking at the original registration submitted by Arcturus that's dated 5/21/35 & registered 6/6/35 by the RMA... Possibly the lack of the G in the type was just an omission but if so, it was duplicated i several places...

BTW Jim Cross is the Chairman of TCA that Lud is President, his work documenting the RMA tube registrations came several years after Tube Lore was published...

http://www.tubecollectors.org/index.htm

Tom

I know all that but Lud seems to be more up on the tech stuff and details from watching both of their postings.

Id call it a draw

Carl