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 Post subject: Sharp Cutoff Octal RF Pentode?
PostPosted: Apr Sun 29, 2012 12:07 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 604
Location: Charlotte, NC, USA
I am working on a late 30s Wards Airline console that uses two type 6J7 tubes, one as a 1st. detector, and one as a 1st. audio amp. One tests borderline weak, and one tests halfway up the "bad" scale section on the tube tester. Does anyone know of an alternative type of sharp cutoff octal pentode that could perhaps be used, even if it means rewiring the socket? The 6J6G has a top grid cap, so the rewiring could include the possibility of wiring the grid under the chassis at the socket, instead of having the top cap. Is there a sharp cutoff version of the 6SK7, for example (more modern)?


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 Post subject: Re: Sharp Cutoff Octal RF Pentode?
PostPosted: Apr Sun 29, 2012 2:09 pm 
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Posts: 11441
Location: Albuquerque, NM 87123
6J6 is a 7 pin tube, with no cap.

Why not just get the 6J7 tubes and be done with ? The only sub for the 6J7 is the 6W7, which is not that common.


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 Post subject: Re: Sharp Cutoff Octal RF Pentode?
PostPosted: Apr Sun 29, 2012 2:14 pm 
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Location: Livermore, CA
Dave

The sharp cutoff version of 6SK7 is 6SJ7 but this requires rewiring. Agree with Johnnysan, why not get a 6J7? You could try a 6K7, remote cutoff, until you get the proper tube.

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 Post subject: Re: Sharp Cutoff Octal RF Pentode?
PostPosted: Apr Sun 29, 2012 3:36 pm 
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Location: Raleigh NC USA
Agree. 6J7 tubes are not at all hard to find, nor are they particularly expensive.

Larry

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 Post subject: Re: Sharp Cutoff Octal RF Pentode?
PostPosted: Apr Sun 29, 2012 5:20 pm 
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Location: New Hampshire
Put which ever one works best in the mixer and the other in the audio and order new ones from one of the ARF sellers in the classifieds. Even a weak one should work on the BCB and at audio.

As mentioned it is a common tube.

A sharp cutoff 7 pin could be a 6AK5, 6AG5, 6CB6, 6AU6, etc, there are many.

Carl


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 Post subject: Re: Sharp Cutoff Octal RF Pentode?
PostPosted: Apr Sun 29, 2012 9:57 pm 
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Location: Utica, NY 13502 (USA)
I think the 6J6G that Dave mentioned is a typo...probably meant 6J7G. I would want to restore the radio as originally wired rather than substitute different tubes with different base configurations.

Dave


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 Post subject: Re: Sharp Cutoff Octal RF Pentode?
PostPosted: May Tue 01, 2012 4:46 am 
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Joined: Jul Sun 09, 2006 3:11 am
Posts: 1951
Location: Aurora, CO
6J7G is common. I probably have 3 or 4 NIB in my tube shed black hole.


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