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Can I mount a 5R4WGA at a 10 degree angle?

I am thinking of a new design for a tube crossover and want to mount the 5R4WGA rec tube at a 10 degree angle. Will that cause a problem?

Here is a pic of everything I have to work with.


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Directly-heated tubes can suffer from problems if operated on an incline.

Does the datasheet say anything in particular about mounting at angles? I have seen some explicitly say not to. I think that the issue is that with some (all?) hanger/filament designs, things can sag in weird directions when the filament is hot when operated at an incline.

I would guess that 10 degrees wouldn't shorten life by much if at all, since it is not that big of an angle. If you have a good aesthetic reason to do it, I would say go for it. Is this a particularly valuable tube? (I don't use rectifier tubes, so I don't know what they are worth.)
The filaments in a DH tube expand considerably when the heat is on. The slack is usually taken up by the spring finger holding up the peak at the top.

If the 10 degree angle is such that pins 1 and 4 are in a vertical plane the sag if any will keep the filament evenly spaced between the two sides of the plate.

Otherwise the filament can sag closer to the plate at one point, causing more current to flow at this point, then bad things can happen.....usually sparks, sometimes a blown filament that can touch the plate putting AC on the caps.....bang.

Tung-Sol says it's for aircraft

Yes, this tube was developed for the first gen B52 bomber.
Is there a rec tube with that type of base that can be mounted in any direction? As you know, I like my gear to be little metal sculptures and that base, in this situation, is intrical to the atheistic of this piece.

OR....is there a socket piece I can use to lift the tube up and use a normal rec tube that can be put in an position?
There are solid state solutions that are supposedly drop in replacements, but you don't get that tube look and warmth of blackened metal inside a glass envelope. These can probably be mounted in nearly any direction. Look up Weber Copper tube rectifier.

Or what you could do is just go 4 dioodes solid state inside the metal part (making sure it is well insulated) for cheaper.
If you need a tube to look as a part of the sculpture, then maybe put the solid state rectification hidden somewhere (chassis, plinth, concrete base, etc.) and then put your prettiest and unusable tube in the metal part of the sculpture at that 10 degree slant without worrying about ill effects of alignment.

The advantage is that you could use a long dead and gone power tube with a similar skirted octal base shape, Coke bottle shape, bulb shape, KT88 heavy in the middle shape, the long EL34 shape, stout 6550 shape, miniature, sub-miniature, anode on top style, cookie jar style, in clear glass, blue glass, or black metal envelope, and for 6.3 volts you get a glow (be one heck of a glow if we can see it through a metal envelope though).

And place the 5R4WGA tube somewhere else level and safe in the sculpture (doing away with the SS rectification). Or you get to keep that 5R4WGA for your next amplifier and not worry about some possible catastrophic failure some time in the future.
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Thanks Over. I need the tube look as part of the sculpture. I could do SS and keep the tube for looks but I'd rather go straight tube.

"Otherwise the filament can sag closer to the plate at one point, causing more current to flow at this point, then bad things can happen.....usually sparks, sometimes a blown filament that can touch the plate putting AC on the caps.....bang."

Better not mount it too close to the grenade, then!!! :D

Any directly heated tube can have a sag problem because the filament wires are not enclosed and are free to move. The 5U4 has much thicker wire, but no spring hanger to hold them under tension.

To solve this problem, use a rectifier that is indirectly heated. If these are within your electrical specs, look at 5AR4, 6AX5, 6BY5 or ANY pair of TV damper tubes, 6AX4, 6AU4... There are dozens of damper tubes in the Novar and Compactron base. They are cheap, and the sockets typically fit in the same size hole as an octal tube.


2011-04-29 8:37 pm
Thanks Rayma. I read that many times and still don't understand it.

Ok for example, if the amp's top plate tube mounting surface is tilted from the front to the back,
then the vertical plane mentioned is parallel to the sides of the amp (if it is rectangular).
Then the tube pins 1 and 4 must lie on that plane.

This means that (for this case) if you draw a line on the top plate from front to back, the socket
is rotated in its mounting so the tube pins 1 and 4 are both on that line. A picture would be easier.
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