kenpeter said:
Try comparing it to these photos:
http://www.tube-classics.de/TC/Tubes/Valvo EL84/EL84.htm
http://www.tube-classics.de/TC/Tubes/SieTel EL84/EL84.htm
No matches to EL84 of European manufacture, it probably US 6BQ5.
Getter is declined like the Mullard, but its a solid dish, not merely
a ring. The plate has very smooth bends and a folded seam. There
are no round holes, only a small notch at the top and bottom edge.
I don't know if those count as "slots" for purpose of a description.
There are no dissipative structures to be seen above the top mica.
No crosses, nor boxes, nor wings...
Getter is declined like the Mullard, but its a solid dish, not merely
a ring. The plate has very smooth bends and a folded seam. There
are no round holes, only a small notch at the top and bottom edge.
I don't know if those count as "slots" for purpose of a description.
There are no dissipative structures to be seen above the top mica.
No crosses, nor boxes, nor wings...
6BQ5 logo barely etched into the glass, looks almost exactly like
the one seen here on the RCA. If there was ever a red RCA logo
on mine, rubbed off long before I ever got hold of it.
https://www.tubeworld.com/6bq5.htm
the one seen here on the RCA. If there was ever a red RCA logo
on mine, rubbed off long before I ever got hold of it.
https://www.tubeworld.com/6bq5.htm
RCA used eight sided logos, so did Tungsol. It's definitely a beam tube, not a "real" pentode. I've got four different flavors of 6BQ5 - two Russian (6p14p and 6p14p-ev), one British (Mullard), and one USA (Sylvania). I'm pretty sure all mine have suppressor grids by counting the grid rods poking through the top of the mica. I can almost see them by peering through the plate holes too (except for the Sylvania, which has no holes).
It is very strange, because I believe that European patent on pentodes was already expired when 6BQ5 were produced.
Pin 1 Bent over and touching Pin2, maybe welded...
Pin 2 G1
Pin 3 Former & Cathode (tied to the far side of Former)
Pin 4 Heater
Pin 5 Heater
Pin 6 NC
Pin 7 Plate
Pin 8 NC
Pin 9 G2
Which is also sort of odd... I thought Pin1 was supposed
to be either a NC, or internally tied to 6 and 8, not 2...
Pin 2 G1
Pin 3 Former & Cathode (tied to the far side of Former)
Pin 4 Heater
Pin 5 Heater
Pin 6 NC
Pin 7 Plate
Pin 8 NC
Pin 9 G2
Which is also sort of odd... I thought Pin1 was supposed
to be either a NC, or internally tied to 6 and 8, not 2...
I doubt this slight misalignment of the supressor poses
much of a problem? Its not anywhere close to shorting
anything else. And all the active elements look good.
Note absolutely no alignment of screen to the shadow
of G1. Totally unlike the RCA beamer.... Also unlike RCA,
this one has cooling fins up top for G2.
6P15P supposed to be 6BQ5/EL84 equivalent, right???
-----------------------------------------------
And I might add, this is one HEAVILY leaded bottle and
unusually thick dark (even to XRAY) getter. Voltages
on the machine cranked almost as far as I dare.
much of a problem? Its not anywhere close to shorting
anything else. And all the active elements look good.
Note absolutely no alignment of screen to the shadow
of G1. Totally unlike the RCA beamer.... Also unlike RCA,
this one has cooling fins up top for G2.
6P15P supposed to be 6BQ5/EL84 equivalent, right???
-----------------------------------------------
And I might add, this is one HEAVILY leaded bottle and
unusually thick dark (even to XRAY) getter. Voltages
on the machine cranked almost as far as I dare.
Attachments
Wavebourn said:
Ah yes... the age old question. Something about a "fragile screen grid" on the SV83? I can't remember which camp everyone is in.
I wonder if that other "6BQ5" in the earlier photos was really a 6AQ5 stuffed into a nine pin bottle.
Wavebourn said:
Me too. I've seen the photos, and I can't tell any difference peering through the inspection holes.
Of course, if someone could conclusively prove their constructions actually are identical, how will it affect their market values? 🙂
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