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Author Topic: 12DQ7 vs.12BY7A  (Read 4708 times)
W4OP
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« on: May 01, 2013, 06:22:23 PM »

Can someone in the group comment on the suitability of replacing a 12DQ7 with a 12BY7A? I see some sites show them as equivalent- not sure how well  this applies to an HF RF application- driver tube.

My 12DQ7 is dead and I have a pile of 12BY7's.

Tnx,

Dale W4OP
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AC5UP
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« Reply #1 on: May 01, 2013, 06:49:35 PM »

Here's a site that says they cross, and the info came from the ARRL Handbook (who could argue with that?):  http://www.nj7p.org/Common/Tube/SQL/Tube_query.php?Type=12DQ7

Unlikely you'll break anything by trying, and that's one way to find out...........
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KE4DRN
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« Reply #2 on: May 01, 2013, 06:52:00 PM »

hi

http://www.nj7p.info/Common/Tube/SQL/Tube_query.php?Type=12by7a

73 james
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W7VO
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« Reply #3 on: May 02, 2013, 09:52:41 AM »

FWIW, my RCA Receiving Tube Manual shows 12BY7A/12BV7/12DQ7 all on the same page, with the same specifications.

73;
Mike, W7VO
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W4OP
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« Reply #4 on: May 02, 2013, 03:28:40 PM »

Thanks guys- I'll try some this evening.

Dale W4OP
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G3RZP
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« Reply #5 on: May 04, 2013, 08:48:00 AM »

Why would they make the same tube under three different type numbers?
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K1CJS
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« Reply #6 on: May 04, 2013, 09:41:54 AM »

Why would they make the same tube under three different type numbers?

Could be that there is a height difference or some slight difference in the tube diameter that the specific tubes were made for.  Envelope differences often existed and with certain manufactured electronic devices the specified tubes had to be used because of that, even though the tubes with the other IDs could have worked as well.
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KE3WD
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« Reply #7 on: May 04, 2013, 05:43:43 PM »

Why would they make the same tube under three different type numbers?

Didn't look this particular instance up, but it may also be due to different manufacturers concurrently developing a tube for the same purpose as well. 


73
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KC6USM
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« Reply #8 on: August 26, 2013, 01:44:28 AM »


                         Hi, A 12by7a tube can be substituted with a 7054 or 8077 also.... F.Y.I..  Gary  kc6usm
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KD0REQ
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« Reply #9 on: August 28, 2013, 08:17:01 AM »

often a manufacturer (Zenith is the best example) would want to capture all the service as well as the initial sale, so they put their own numbers on other tubes.  often they would have a couple of pins rerouted just to say it was a Zenith part.  Majestic put wacky filament voltages on a lot of tubes to capture the market all the way down the chain.  nobody else wanted a piece of that action, it was too extreme.
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