Ground isolated from chassis - now it's an AM radio [message #30842] |
Sat, 05 March 2005 16:35 |
colinhester
Messages: 1349 Registered: May 2009 Location: NE Arkansas
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Illuminati (3rd Degree) |
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I got some teflon tape wrapped around the volume pot to isolate it from the chassis. That seemed to be the point of contact between the signal ground and chassis. Now when I touch the metal volume shaft, I get WLW clear as a bell. Pretty cool, Doug!! How did you manage to design that? The noise at full attenuation without signal has gone down quite a bit just by isolating the chassis, so I'm pretty happy I'm still chasing down the hum. I did the star ground off the volume pot's ground node, so this might be the problem. I'm going to move the ground point over to the inputs and use heavier gauge bus wire. I was using wire that was thinner than the in B+, except in the connection going to B-. Hopefully all will be sorted out this evening. Now if I can just figure out how to tune in something other than WLW......Colin
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Re: Ground isolated from chassis - now it's an AM radio [message #30866 is a reply to message #30865] |
Sun, 06 March 2005 09:34 |
colinhester
Messages: 1349 Registered: May 2009 Location: NE Arkansas
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Illuminati (3rd Degree) |
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This is the same wire that is used in Bottlehead's SEX kit, so I followed thier directions on use. The red wire is used as the signal wire and is hooked up as nornal. The black wire is the the ground and is hooked at one end to the ground. The drain bare drain wire is wrapped around the black wire at the ground end and soldered. The shield is pulled back far enough to accomplish this. Essentialy at one end the black and bare wire at arrached to ground and the red signal wire is to the siganl's path. At the other end everything is trimmed back except the red wire, which is hooked to the other end of the siganl's path. I noticed on several connections that I had stretched the red wire's insulation enough that it was making contact with the foil shield. I just got in a hurry and used linesman's strippers to strip the black outer casing. The teeth cut a little too deep and caught the inner casings. I did not notice this until I started to examine my solder connections under an 8x loupe. I then checked for continuity between the siganl and ground and had full contact, damn....Colin
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