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US 6L6GC identification

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Hi all,

Going through one of my boxes I came across some 6L6GC's that I'd like to identify.
All have black plates and have the type inside an octagon.
There is a Baldwin that bears the production code 60-09 274. That should mean is is made by RCA in september 1960, right?

Compared to the Baldwin, the two Mazda-Belvu's have no codes, side getters instead of bottom getter and a different number of teeth on the spacers. However, the plate structure and the cutouts in the spacers look identical.
So I conclude that these are made by RCA as well.

The last one has no label other than the octagon with 6L6GC in it and '270' underneath.
Top getter (ring), slightly longer heat fin on g1, welded plates (with 5 small holes that show the support rods), dull grey beamplates and a rectangular spacer with much simpler cutouts than the RCAs.
Who made this one?

thanx,
PF813
 

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Well if nobody is going to field this one I will give my guess. I think they are all RCA. I personally see all black plates, which I believe you have confused with the mica spacers......please correct me if I am wrong. The 270 EIA code looks like a 274 to me but the picture is a tad blurry. 270 would be Quam-Nichols which I don't think made tubes.
 
Hi FMB,
The '270' was hard to photograph.
This one is clearer.
attachment.php


It also shows distinctive 'flaps' along the long side of the top and bottom of the beam plates and some ridges in the plate structure.
I found these same shapes in some (grey plate) Sylvanias. RCA and GE don't have these.
Maybe it's a 'pre-STR' 6L6GC?
 

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Indeed, that is the 274 code on the Baldwin.
The two Mazda-Belvu labeled ones have no EIA code and the unlabeled one has the mysterious '270' on the glass.
Since this and the Mazdas came in the same French boxes, I contemplated the possibility of a European production. I only thought the type inside an octagon was exclusively USA made.
 
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