Has anyone tried the directly heated double tetrode QQC04/15 (aka 5895) connected as a triode? There appears to be a low frequency (audio?) push pull option in the tube data. G2 is limited to 250V and is shared.
Wonering if a pair could make a worthy project some time down the line.
Valve museum
Wonering if a pair could make a worthy project some time down the line.
Valve museum
if you have a stash on hand 😀 and those damned sockets ... don't go above Vg2 = 200v
I did 2 amps with QQE03/12, easy to find, cheap, tetrode only as Vg2 might not sustain more than 150v ...
I did 2 amps with QQE03/12, easy to find, cheap, tetrode only as Vg2 might not sustain more than 150v ...
B8B bases were very popular in the UK ,first by UK/USA military in WW2 then after the war from (approx ) 1947-1954 they were extremely popular in British radios.
The UK issued a full radio tube range in the "7" series ,one of the reasoning's for this base was its better hold on its tubes when used in portable military situations but even by then direct pin contact in all glass construction was already being used in the shape of the "Acorn " tube used for VHF type RF reception/transmission which morphed into the B9G tube then B7G tube then --B9A tube .
For those on the continent having trouble finding bases just buy an old non working British radio of that era, I repaired 100,s of them .
As I read all the posts about the use of unusual tube types in audio now I am surprised nobody has posted on an "Acorn " tube being used as an audio amplifier.
Acorn tube - Wikipedia
I actually have (boxed ) US military issue "Acorn " tubes sold to the UK military in WW2 -- a "Lease Lend " enterprise.
The UK issued a full radio tube range in the "7" series ,one of the reasoning's for this base was its better hold on its tubes when used in portable military situations but even by then direct pin contact in all glass construction was already being used in the shape of the "Acorn " tube used for VHF type RF reception/transmission which morphed into the B9G tube then B7G tube then --B9A tube .
For those on the continent having trouble finding bases just buy an old non working British radio of that era, I repaired 100,s of them .
As I read all the posts about the use of unusual tube types in audio now I am surprised nobody has posted on an "Acorn " tube being used as an audio amplifier.
Acorn tube - Wikipedia
I actually have (boxed ) US military issue "Acorn " tubes sold to the UK military in WW2 -- a "Lease Lend " enterprise.
The B8B base was introduced by Philips into the European market in the 1940ies. There were quite successful Loktal tubes for consumer table radios: AZ21, EBL21, ECH21. The latter ones also were marketed by C.F.Lorenz under the EBL71 and ECH71 monikers. And don't forget those 807 equivalents 5B/254G through 5B/258M by STC.
Best regards!
Best regards!
Of course 🙂! What I wanted to point out is that the B8B base was also widely used in continental Europe.
Most probably it has been derived from the related B9G base, see »the tube that won the war« EF55.
Best regards!
Most probably it has been derived from the related B9G base, see »the tube that won the war« EF55.
Best regards!
... and early especially in "v1 Paraset transceiver" (v2 was octal) shipped from UK in France to prepare Overlord ... (a friend of mine still use his grandfather's own)
2degGM 1942 Radio Wirelless Type 3 Mark II B2 Paris :Maquetland.com:: Le monde de la maquette
2degGM 1942 Radio Wirelless Type 3 Mark II B2 Paris :Maquetland.com:: Le monde de la maquette
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The 5895 & several others RF tubes like it (815, 829B, 832, Etc) all have only one screen connexion. So maybe OK for paralleled SE triode operation but PP is not possible. Unless another 5895 is used.🙂
Am I missing something??😕
Is it impossible to have a single regulated supply for the screen, and then use it in a push pull way? Or does the lack of a suppressor mean that there is no reasonable operating point?
But, I had wondered how they would be as triodes, paralleled and being directly heated, if that would be a substitute for a more exotic tube. I guess the low g2 voltage stymies that.
Yes, of course, feeding both screens and PP is exactly what this tube is designed for.
Best regards!
Best regards!
A single tube in push-pull is definitely possible but not in triode mode, tetrode connected only.
A pair of tubes - the two sections of each tube in parallel - could be run push-pull in triode mode though. Most tetrodes / pentodes do well in triode way beyond their max g2 voltage specs if the max g2 dissipation is obeyed. The lack of a suppressor grid has no influence on operating points, and the nasty kink in tetrode curves does not show up in triode mode either.