[Hallicrafters] Another De-Oxit caveat.

[Craig Roberts]

I'm a big fan of De-Oxit.  Great stuff!

However -- to reiterate the postings of many -- ya gotta be careful 
about where and how you apply it.

Now, we've all heard the "swelling of phenolic wafer" stories, so I 
won't repeat that warning -- however -- here's a new one:

A couple of days ago I asked for clarification of the Hallicrafters 
SX-series crystal filter alignment instructions; the factory published 
ones being wholly incomprehensible to some of us.  I got no answers, but 
dove back into the radio last night anyway. 

I decided to check the condition of the crystal itself since its 
excitation peak seemed ambiguous and nomadic when I attempted to locate 
its precise frequency. (It seemed to vary in intensity and frequency).

The crystal is contained within a holder "sandwich" comprising phenolic, 
Bakelite or micalite outer halves and an inner ceramic "frame" 
surrounding the crystal itself.  In my receiver, over the years, this 
ceramic piece had cracked in three places due to mechanical or thermal 
stress, I would guess. These cracks allowed fluid to migrate through 
capillary action into the interior of the holder, contaminating the 
crystal.  Although I have been careful in my application of De-Oxit, I 
fear that  it might have been one of the contaminating fluids (unless 
the crystal holder is mysteriously oil-filled), especially since it's 
mounted on the radio's mode switch.

Ar any rate, please be careful with the application of De-Oxit or any 
other chemical in ALL parts of your radios.

Incidentally, has anyone replaced the crystal in these radios with a 
modern, wire-lead type?  If so, what were the specs (besides 455 KHz)?

73,

Craig
W3CRR