The AM Forum

http://www.delphelectronics.co.uk/filter390a/

Hey John FXE if you can do a poncho intake gasket job in 5 hours you can pull this off...gfz

I wouldn't want to get into that. Pretty intricate assembly.

Fred

Does FXE have a bustedo filter??

Anyhow, I'm game for that repair... think it is do-able... the worst part is getting the blang solder out of the can's seams! That and not cooking the innards in the process... after that, the next question is if you want to replace the stupid foam with something else or keep using foam... maybe a vacuum suck out and nitrogen fill followed by a seal off to keep the foam fresh forever?? Or maybe inert gas? Or does the resonance get effected by the "atmosphere" in the can??


              _-_-WBear2GCR

Question:

For the case where the filter's output coil has some leakage resistance to ground, but the filter is otherwise still working:

Why not capacitively couple the the output of the filter to the grid of the tube... and connect the AGC line directly to the grid of the tube?

Stu

Or mount the filter on stand-offs or otherwise keep the case insulated from ground, and grounding the case with a by-pass capacitor.  With the 75A-4's plug-in filters, this could be accomplished at the underneath side of the filter socket.

I would want to have all the appropriate tools ready before beginning that rebuild project, but I saved the web page for future reference. You have nothing to lose if the filter already appears to be crapped out.

Another thing the article demonstrates is that it would be unwise to physically jolt around an older mechanical filter, even one that works perfectly.  That means an extreme amount of bubble wrap and multi-boxing in a large shipping carton if one of these is to be subjected to the standard torture and abuse at UPS or Fedex.

Anyone know offhand where I might find one of those miniature butane torches like the one shown in the photos?  I can think of many uses I would have for one.  All I recall seeing in the local stores are the standard, large size ones like you use to thaw out pipes, although I have not actually looked for one of these small jobbies.

Don I bought my butane torch just like the one pictured, (except in orange) at Harbor Freight for $10 a few years ago.

73,
Jack wa9nqw

Don,

As Jack stated Harbor Freight has them and you can get them with or without the built in pizeo igniter.  Having built in ignition is definitely the way to go.  They refill with the standard butane cigarette lighter canisters.  They are perfect for outside antenna work.

Rodger WQ9E