[AMRadio] D-104 modifications


D. Chester k4kyv at charter.net
Sat Aug 28 13:50:56 EDT 2010


I'm not really worried that D-104 cartridges will become unobtanium any time 
soon.  They seem to be all over the place at every hamfest I attend, and the 
going price is usually between $35 and $50.  Probably less than what Astatic 
would charge for a new cartridge if they were still in the business. Plus 
you get the head and stand to boot.

Some will have crapped out elements, so it's kind of like buying a tube at a 
hamfest if you don't have some way to test it.

The worst case I have seen is one that I picked up for a few bucks.  It has 
output, but sounds terrible.  Like a recording of a tin can telephone played 
through another tin can telephone.

I opened it up, and someone had punched the diaphragm full of holes, so that 
it looked like a salt shaker.  Later, I was told that was a common 
"modification" by the CB crowd.  No idea what they were trying to 
accomplish.

I still have that element, along with another one with a crapped out 
crystal.  I have thought that some day I might try to see if I can dissolve 
the wax or glue that holds it together and try to swap the diaphragm in the 
crapped out one with the damaged one in the good-buddy mic.

Rochelle salt crystals can be made at home from baking soda and cream of 
tartar.
http://www.seawhy.com/xlroch.html

Look at this beauty:  http://www.seawhy.com/xlrs.html

The only reason that I could think of that salt crystals could not be 
obtained is that no-one is manufacturing them commercially for phono 
cartridges and microphones.

It would seem that someone would go into the business of building 
after-market replacement cartridges identical to the originals, just like 
automotive parts, if there were much demand for them.  If the damand is that 
low, that means that the mics should be widely available for a song for many 
years to come, or until all the existing crystals are finally crapped out 
due to age.

I would never think of sending any of my antique heads to Astatic or whoever 
owns them nowadays for a replacement cartridge.  It wouldn't surprise me to 
get back a different one, a new good-buddy version.  They might just swap 
out the microphone for a repaired one they have on the shelf, and you would 
get a whole replacement microphone, and they would fix the old one later to 
swap out to someone else.  Even if I got the original one back, I'd be 
afraid they would manage somehow to screw it up.

Don k4kyv
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