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RE: DB110G (Bogen) 1950s.

Of course you can carry on collecting stuff for ever, but it's of little use.
Currently the loctal 7C5 go for peanuts.
I bought a large qty of Mcmurdo loctals to put them in if needed.
The 6L6 types can also be had for peanuts in loctal using the 254/255M series from STC - UK mil spec made.

I managed to start up a pile of them making an adaptor from UX to Loctal, and found out NOS is not so smart.
Production spread is huge, and some just arced on startup.
I did manage to make a matched quad like that and a few pairs, but then what to do with them? 807s/6L6 are known for hideous amounts of 3rd harmonic distortion.
The much vaunted KT66 was a distortion mush maker, but few seem to worry.

As for the Bogen I will convert it to EBL71, another superb piece of kit with much lower distortion than any 6V6 and 2-3x the gain. Those also can be had for peanuts, as they made zillions of them in E Europe for lousy noisy old AM radio sets.
They are supposed to run the same A-A load as the 6V6.
Look how low the anode voltage can drop without losing linearity!
It's going down to 20-40V and still conducting!





Now compare it with the dirty old 6V6oids..





Pentodes can reduce IMD, now you see why.
That particular one (with the 2 redundant diodes) was scarcely ever imagined in push-pull and has no info on fixed bias at all.....ie. probably works brilliantly without all that beam tetrode IMD, and heavy THD.


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  • RE: DB110G (Bogen) 1950s. - ivan_terrible 01:32:15 12/28/23 (0)

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