Where can I get the old style MXR non-conductive foam?

[10acErnie]

I modded my Script MXR Dyna Comp with true bypass switching, a LED indicator, and battery adapter. I put it in a Hammond 1590B box so I wouldn't modify the original box in case I ever want to restore it back to original.
The problem is now when I close the new box I get a radio station. I suspect it may be the foam I'm wrapping the circuit board in. The original MXR foam is rotted beyond use. I didn't get the radio station before I switched everything over, and I don't get the radio when the box is open.
Does anyone know where I can get the old style MXR type non-conductive foam?
I read in past posts of people using cut up mouse pads. I may try that for this one but I have some other old MXR pedals that could use some new foam and I figured why not fix 'em all!

[vanhansen]

Since when is foam conductive?  I suspect something else is making the radio stations come in.  If you wrap the board in plain old paper and close the box does the radio station come in?

[10acErnie]

Since when is foam conductive?  I suspect something else is making the radio stations come in.  If you wrap the board in plain old paper and close the box does the radio station come in?

Sorry! Maybe I should have said insulating foam. Would paper be a good insulator? I'll try that.

[PenPen]

I could be wrong here, but I'm pretty certain that foam has nothing to do with the RF you are getting. To get RF from the FOAM it would have to be conductive to act as an antenna. I suspect you didn't ground the new box properly.

[vanhansen]

Since when is foam conductive?  I suspect something else is making the radio stations come in.  If you wrap the board in plain old paper and close the box does the radio station come in?

Sorry! Maybe I should have said insulating foam. Would paper be a good insulator? I'll try that.

You can try using paper just to eliminate foam as the culprit but PenPen is on the right track.  There's a grounding issue in there somewhere.

[10acErnie]

I could be wrong here, but I'm pretty certain that foam has nothing to do with the RF you are getting. To get RF from the FOAM it would have to be conductive to act as an antenna. I suspect you didn't ground the new box properly.

Thanks guys! I'll recheck my work. I put paper in there and still got the radio. I also tried making a pad of duct tape and the radio is still there. Funny thing, there's no radio when the box is open.

[Paul Perry (Frostwave)]

Absolutely anything is possible in RF pickup. In this case, it is possible that putting the back on, adds a certain amount of stray capacitance, just enough to make a length of lead into a tuned antenna. I'd try the usual anti-RF tricks, a 22 pf cap across the input to ground, a .01 on the output to ground, a ferrite bead on the input right at the jack or anything else anyone ever saw work. Is the RF still there when you put another box (any kind) between the guitar and the offending one?

[DavidS]

Just to chime in on the foam, there IS conductive foam. Most of the foam in my house is conductive. Think computer parts, like motherboards, etc, or any static-sensitive components that are shipped sans-chassis. I once killed a botherboard's keyboard controller by powering it up while it was sitting on a chunk of conductive foam!

[PenPen]

Yes, of course. I don't believe he is using conductive foam, though. I presume he is using the foam to hold the PCB off of the case. If the foam were conductive he would have been shorting the contacts on the PCB though the foam then, and he would be getting nothing from the box (I've done this in a Boss effect once).

What I always use for box insulation is some cut up plastic from one of those folder things you get from a dept store or any office supply store. Used for presentations. I just cut a peice to fit the box and put that across the back.

I still wonder if he has grounded the chassis at all.

[vanhansen]

What I always use for box insulation is some cut up plastic from one of those folder things you get from a dept store or any office supply store. Used for presentations. I just cut a peice to fit the box and put that across the back.

Clear slides cut to the right size work great.  That's what Boss uses.  Theirs just have some grooves in them.  It's a great idea.

[petemoore]

  I've been using the clear, thick, tear resistant theft prevention plastic packaging used to 'enlarge' small expensive items.
  You probably have some of that laying around, or have discarded alot of it, just find a flat portion, [though I like to use the 'edge lip' to reach around the corner of the board when it's going into a corner of the box] and cut it to size .. put between the board bottom and the conducting case material to achieve free, very permanent and well insulated status.

[10acErnie]

Absolutely anything is possible in RF pickup. In this case, it is possible that putting the back on, adds a certain amount of stray capacitance, just enough to make a length of lead into a tuned antenna. I'd try the usual anti-RF tricks, a 22 pf cap across the input to ground, a .01 on the output to ground, a ferrite bead on the input right at the jack or anything else anyone ever saw work. Is the RF still there when you put another box (any kind) between the guitar and the offending one?

I tried the pedal in between two buffered pedals and it seems slightly better. I probably won't get a chance to get to it for a few days but I will try the other anti-RF tricks you suggested.

Yes, of course. I don't believe he is using conductive foam, though. I presume he is using the foam to hold the PCB off of the case. If the foam were conductive he would have been shorting the contacts on the PCB though the foam then, and he would be getting nothing from the box (I've done this in a Boss effect once).
<snip>
I still wonder if he has grounded the chassis at all.

Sorry, I should have been clearer in my original post. I should have said "foam that would be good for insulating" instead of "non- conductive foam." The foam I was using is the thin stuff that comes in a sheet and is used for shipping. If you hold it up to the light you can just about see through it. It has a lot of very tiny holes. It was all I had laying around. I have a few other old MXR pedals kicking around and I was wanting to replace the foam in them too. I figured someone might know of a similar type to the original that MXR used.
The foam was definately not the problem though, the other materials I've tried didn't cure it either.

I checked the box and it is grounded but the old MXR stuff doesn't use the star grounding method that a lot of people are using today. I wonder if star grounding would make a difference?

Thanks for the responses! I will try the other suggestions and report back.........