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Old 19th September 2009, 09:56 AM   #1
Arnulf is offline Arnulf  Europe
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Question Dual HF small signal pentodes ?

I am looking for a dual identical small-signal HF pentode in noval package, essentially a noval version of EFF51. Common cathode, internally connected supressor grids, high-mu, sharp cut-off, high frequency operation.

Does such a beast exist at all ?
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Old 19th September 2009, 10:15 AM   #2
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Oh carp, I had one that fit that bill for VHF, but tested toasted so I turfed it.

It was a numbered unit, so a boo through the RCA Transmitting Tube manual should bring it up

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Old 19th September 2009, 01:31 PM   #3
Yvesm is online now Yvesm  France
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Not exactly a small signal unit, but not so "powerfull" !


Also know as QQE02-5 this side of the sea.
I used one -long ago- in my very first TV transmitter, cathode modulated with a single 2N1711
Today, I could build a pentoded LTPI with that !
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Old 19th September 2009, 10:27 PM   #4
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I had been looking for such a beast for a long time but could never get anything suitable. There are plenty of dual power pentodes, but these are not that suitable for small signal duty. There are a few Compactrons, but the curves look fairly rubbish.
The best I have come up with is the 12L8GT. This is classed as a low power output pair, but it has a max plate of 180V at about 12.5mA. It should be possible to get it to work at about 7mA and about 120V. Can only find two datasheets, and only one with curves at 180V - though the curves look quite good. Its cheap to.

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Old 26th September 2009, 04:05 PM   #5
Arnulf is offline Arnulf  Europe
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Today I have found the closest thing to what I was looking for: the Russian 6R5P (6Р5П). It isn't exactly specified to be HF but then again neither is the ubiquitous EL84 ... Alas this thing appears to have been made of unobtainium so even if it does show up it is bound to be prohibitively expensive
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