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Old 16th May 2003, 04:46 AM   #1
Duo is offline Duo  Canada
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Default I need a 6A7, 88, and 89 tube.

Hey guys. I have an interesting radio from the thirties that I got working. I'd like to get some better tubes for it though.

The RF amp 6A7, first IF 88, and output 89 seem to be fairly old and weak.

Does anybody have a clue where I might find these? T

They are all old 6 and 7 pin tubes from the 30's.

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Old 16th May 2003, 06:40 AM   #2
SHiFTY is offline SHiFTY  New Zealand
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Well I don't have anything that exciting in my junk box, but www.evatco.com.au has NOS 6A7 and 89 for about $AU25 each (about $US15...) They are pretty good with their tubes, nicely packed and so on.
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Old 16th May 2003, 10:19 PM   #3
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Assuming that it's a 78 for the IF (88 is a full-wave rectifier), I have 'em. How about $3.50 for a NIB 89 (tho the box don't loook so new...) and $3.50 for a used, tested 6A7 and $2.00 for a tested 78 (or 6D6, slightly different in height). If you're in Canada, $4 would get them to you.
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Old 31st October 2003, 01:38 AM   #4
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Actually, I know that 88 is a rectifier. However, there's an older 88 that is a radio stage tube. The tube I have is quite clearly marked.
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Old 31st October 2003, 01:55 PM   #5
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Sometimes when I get an old radio which has defunct tubes that are difficult to come by, I'm inclined to replace the tube and its socket for an electrically equivalent type which is more easily available. Vintage purists might disagree, but I think that it better to have a working set with 'period' parts in its repair than a non-working dust-gathering piece!

Your 88 is a rare tube - I've never come across one 'in the flesh.' The octal based 6SK7 is the electrical equivalent, so replacing the 88's UX base with the octal type should not upset circuit conditions. As an IF amp you might find that a 78 (electrical equivalent of a 6K7) could work. I don't know of an equivalent for the 89, although I suspect that an octal 6V6 could be used with minor circuit alterations.

I think that the 6A7 is more likely to be used as a frequency changer than a RF amp - the 6A8 is the octal equivalent. The 6A7 can be obtained from Billingtons in this country ( http://www.bel-tubes.co.uk/ ) but they don't have the other types.
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Old 31st October 2003, 02:35 PM   #6
Duo is offline Duo  Canada
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I had those ideas in mind, but unforunately, I'm one of those purists.

I'm in no rush to get new tubes for the radio just yet, I'll wait untill I come across them. I know a person that probably has many of these types of tubes and so one day I'll go over and rummage through his collection.

Thankyou for your insight though.
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Old 31st October 2003, 10:23 PM   #7
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Is the 88 a Rogers number? They had some odd numbers. Does it have a grid cap? Maybe a 78 would work if it's 6 pin. Maybe a 39/44 or a 51 if it's five.
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Old 31st October 2003, 10:26 PM   #8
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Hi,

Quote:
Is the 88 a Rogers number? They had some odd numbers.
I think that's the one...

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Old 31st October 2003, 10:49 PM   #9
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Yes, its listed in one of my tube manuals (published in 1954) as being manufactured by the 'Canadian Rogers Co, Canada.' Unfortunately, the manual regards it as an obsolete type (even in 1954!) so it doesn't give the base connections. However, I believe it uses a standard six pin UX base so I imagine the pin connections are the same as a 78.

As said previously, I've never come across a 88, but I have seen other UX based tubes in old radios (and amps!) and they seem to perform as well as their octal equivalents.
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Old 1st November 2003, 07:04 AM   #10
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Well, these tubes are old. I estimate that the radio is from the 30's.
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