I am working on an RCA that is motor-boating. I think it's because the tube shields are missing.

I'm looking for some ideas on how to make shields for tubes like the 6D6, 6A7, 75 etc.

Thanks,
Gary

To test your theory, maybe you can make some temporary shields out of aluminum foil. A rubber band should hold the foil against the clips on the tube socket to ensure a good ground.

Rich

:I am working on an RCA that is motor-boating. I think it's because the tube shields are missing.
:
:I'm looking for some ideas on how to make shields for tubes like the 6D6, 6A7, 75 etc.
:
:Thanks,
:Gary
:

Tube shields of many types can be found on eBay. The more specialized 3 piece types must fit the tube in question, so be sure that you are obtaining the right type. Generally the RF tubes, which are the tubes that usually require shielding, are of the small "12" size, so they usually take one size of shield. If you have an idea as to what the shields originally looked like, you can then have an idea as to what you are looking for. If you don't have a clue, and noone can supply you with pictures of another radio chassis of the same model, then perhaps I can describe what the couplings of several shield types look like. The couplings are the base piece(s) That the shields clip into. The larger ones take the regular can types of shields. The smaller ones usually take the multi piece shields that are split in half.

Also, in case you missed what Rich was saying, the aluminum foil must contact the metal chassis in order to function as a shield. The foil cannot, however, touch the tube pins.

Thomas

:Try using a small vegetable juice can, such as a V-8 or tomato juice 7 oz can. Cut the top and bottom off with a hacksaw. A jagged edge is fine, it actually insures proper grounding with the chassis. I did this for a tube in an early RCA Victor radio, and it worked better than the original factory tube shield!! It is still in the radio today.
Jim

Gary,
I was able to get shields from PTOP (oldradioparts) a couple years ago, but you'll have to describe tube type or include desired dimensions for Gary to find them in his vast collection of stuff.

marv

:I am working on an RCA that is motor-boating. I think it's because the tube shields are missing.
:
:I'm looking for some ideas on how to make shields for tubes like the 6D6, 6A7, 75 etc.
:
:Thanks,
:Gary
:

These tubular metal-mesh drain-hose lint filters can be easily fashioned into a tube shield w/a wire to ground.

They are available in the Hardware store or Supermarket:

Thanks for reviving this old post.

I did find a couple of shields in a box of stuff that I fogot that I had and the motor boating stopped!

Sorry for not posting after I found the shields!

Since then I have found a couple of materials and ideas that could be used:

The first is adhesive backed copper tape. This stuff is used in EMI/EMC test labs. It comes in various widths and is made by 3M. It could be applied to a tubular form made from a material capable of dealing with the heat. Any suggestions on this mystery material?

The second is 0.010 shim stock. A tube shield could be made by bending a "J" lip along each edge of a piece, hooking the edges together then crimping them. The piece of shim stock would need to be (Tube Length x (Tube Circumference + 1/2")).

I like the shim stock idea the best because I think it would look good. I plan on trying this the next time I need large tube shields.

Gary

:I am working on an RCA that is motor-boating. I think it's because the tube shields are missing.
:
:I'm looking for some ideas on how to make shields for tubes like the 6D6, 6A7, 75 etc.
:
:Thanks,
:Gary
: