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 Post subject: 5y3 position
PostPosted: May Fri 19, 2017 11:28 pm 
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Joined: May Wed 31, 2006 6:41 am
Posts: 195
I read somewhere that the 5y3 should be only used in vertical position to avoid the heater touch the plates. How true is that?
I ask because i am about to measure voltages on a radio i amrepairing and to do this i have to put upside down the chassis. When i do that the tubes are at a 45° beause the radio is supported on the dial and the power transformer.
I did this several times before with this radio without ill effects, before i read that.Mybe i just had luck.
It is safe to do this?


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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 12:14 am 
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Location: Indiana, 46241
Hickok tube testers use a 5Y3 and an 83 BOTH mounted in the horizontal position.


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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 12:22 am 
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Location: Livermore, CA
I've never had a problem with a chassis on it's side but RCA has requirements for 5Y3GT. It's preferred to mount the tube vertical. If horizontal pin #2 and #8 should be in a horizontal plane.

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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 12:27 am 
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Location: Maryland 20709, USA
The HB-3 page says pins #2 and #4 should be in a vertical plane if mounted horizontally.

That might be the same as #2 and #8 horizontal.

I would suggest you completely invert your radio, so the 5Y3 is still oriented vertically.

- Leigh

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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 12:44 am 
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Joined: Feb Sat 06, 2016 1:47 am
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Location: Santee Calif. 92071
Filament sag can touch the plate causing a direct short.

http://www.nj7p.org/Tubes/SQL/Tube_query.php?Type=5Y3GT


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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 2:05 am 
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Joined: Feb Sun 05, 2012 5:12 pm
Posts: 505
Location: Syracuse NY
I've always been paranoid about the 5Y3 and 5U4 positioning, so I built an adaptor. It consists of an octal socket mounted on a small base, wired to an octal plug. Be sure to use heavy gauge wire for the filament leads.
The rectifier tube stays upright while the chassis can be moved wherever needed.

Sometimes I'll use a pair of 1N4007 diodes and a resistor soldered to an octal base, but the B+ will be higher than with the tube.

Bob

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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 2:17 am 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island
I've seen a 5U4 short out when a chassis was put on its side. Granted, it is a lot more likely to happen with an old used tube where everything is loose to begin with, but if the power supply is under a heavy load it could happen even with a new tube.

If you look at the plates of the tubes, you'll notice that they are flattened cylinders. From the ends they appear to be oval shaped. So what the RCA tube manual Leigh mentioned is saying is, if you have to put the tube horizontal, orient it so the long sides of the oval are in the vertical plane. This gives the longer distance that a filament can sag before it touches a plate. A healthy tube under normal load should be fine if oriented this way.

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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 9:00 am 
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Location: Mpls, Minnesota
I have had many TV's and radios on the bench over the years and never had a rectifier tube short out.

Dave


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 Post subject: Re: 5y3 position
PostPosted: May Sat 20, 2017 9:53 am 
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Location: Lincoln City, OR
Greetings to the Forum:

I have to go along with Dave.... I have never had any tube failure happen to me on the bench because of orientation. I routinely orient chassis in whatever position facilitates the work.... and never even thought about it. I'm not saying it couldn't happen, but it must be pretty rare.

Note that the tube manuals are written for manufacturers of equipment as well as repair people. It is a different thing to design a piece of gear where the tube is oriented in the wrong direction and runs that way day in and day out as opposed to a necessarily brief interlude on the service bench.

Just my $.02 worth; your mileage may differ.

Regards,

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 Post subject: Re: 5y3 position
PostPosted: May Mon 22, 2017 12:12 am 
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Joined: May Wed 31, 2006 6:41 am
Posts: 195
I just made the measurements, no problems so far.

I think i will make an adapter to put the 5y3 vertical for futire measurements just in case.


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