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 Post subject: FM Alignment using ungrounded shield around Converter tube
PostPosted: Oct Sun 04, 2015 7:10 pm 
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Joined: Sep Mon 10, 2012 10:41 pm
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Location: Phoenix, AZ
If you are like me, you may be irritated by the instructions for FM Alignment that state you should connect the signal generator "High side to ungrounded shield over FM converter tube".

The problem is that the shield in question is riveted, or soldered in place and/or not easy to get to.

The simple thing to do is make your own shield.

You will need:
Masking tape or paper backed shipping tape. (or any tape that can handle 300° temperatures)
Aluminum foil
very small wire.

I used packing tape because it is very sticky.

Start by cutting off a piece of tape and attaching the wire with part of the stripped wire on the tape like so:
Image

Cut a 1 inch x 2 3/4 inch strip of aluminum foil and place it on the tape so it makes good contact with the wire:
Image
you will want the tape to overhang the aluminum by about 1/16 inch.

Cut the excess tape off:
Image

remove the FM Converter tube and wrap the new shield around the tube, carefully insert the tube in it's socket and it should look like this:
Image
Verify that there is no continuity between the actual shield and the one you just made, and now you can do the alignment without having to unsolder the shield or drill out the rivets.

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