[WyTex]

Is the 6L6GA a good substitute for the 6L6G? 

Thanks,
Paul

[morzh]

I think they are only different in shape, being the same tube inside.

[Radioroslyn]

Yes. The 6L6GA and 6L6G are the same, the 6L6GB has a bit better specs as it can handle higher plate voltage and dissapation. Using a 6L6G where a 6L6GBwas used may not be a great idea depending on the circuit and voltages used.
You may find that the 6L6G is a bit taller than the GA.

GL

[jcassity]

taller and fatter,, takes up more realestate

[Arran]

The 6L6G is basically of similar size to a 5U4G, it that is of any help. You could also use a 6L6 in place of a 6L6G but it will look out of place in a Philco. I would consult a tube manual if you want to know whether a GA or GB could be used electrically and physically in place of a 6L6G.
Regards
Arran

[WyTex]

Thanks everyone. I have a 30's era Philco tube substitution booklet but it doesn't list any 6L6G substitutes. Wasn't sure if that was due to no actual substitute or Philco marketing.

Paul

[Arran]

Try the online listings, there are plenty of tube manuals posted out there, RCA, G.E, Sylvania, you name it.
Regards
Arran

[Ron Ramirez]

Paul

What year was your Philco tube booket published? The 6L6 was developed by RCA in 1936 and Philco did not start using the glass version of the tube (6L6G) until mid-1937 (for the 1938 season). So, it would not appear in any tube manuals published before 1937.

As for substitutes, I don't think there were any substitutes for the 6L6/6L6G early on. Variants such as the KT66 and 5881 came later.

[WyTex]

Thanks Arran.  Your comment reminded me that I did print out Sylvania's Tube Substitution Booklet but seem to have lost it in the shop somewhere.

[WyTex]

Ron - after checking my booklet I can't find a production print date on it.  There is a page dedicated to 1942 radios that perhaps is the production year? Photos below.

[Ron Ramirez]

If it has a listing of 1942 Philco models then it cannot be from the 1930s, it must be mid to late 1941.

Philco used the 6L6G tube in the 38-116 and 38-690, then not again until the 42-1016 and (I think) 42-1015. Even then it likely had no direct substitute at that time. I doubt that the KT66 was widely available in this country back then (although I could be wrong), and the 5881 may not have been developed yet (again, not certain without some research).

[David]

Looking at Franks electron tube page info from RCA dated Feb 1957, info from Tung-Sol dated June 1962.  
http://electronbin.com/sheets51.html

[WyTex]

I was mistaken.  I thought it was a late 30's printing but clearly not.  Sorry about that. It's a handy booklet.

Regards,
Paul

[Ron Ramirez]

I'm frankly surprised the 6L6G isn't in your manual for the reasons I mentioned in my previous post (used in 38-116, 38-690, 42-1015 and 42-1016).

You may sub the 6L6G with 6L6GA, 6L6GB, 6L6GC. Also 6L6WGC, 5881, or 7581 (the 7581 is equivalent to a 6L6GB; the 7581A is equivalent to a 6L6GC).

The KT66 has a higher filament current (1.27A) than the 6L6 series (0.9A).

The 6L6G has the largest envelope. 6L6GA is also taper-top or "Coke bottle" shaped but smaller than 6L6G. Starting with 6L6GB, the envelope became tubular, tapered at the bottom just above the base.

[WyTex]

Thanks for the helpful information Ron!

The 6L6G is listed but not a substitute. I was assuming I should use 6L6G 's in s 38-116.

Thanks
Paul