[HBR] Another Receiver Project -- HBR-4, Part 5

[waltah at earthlink.net]

Dan Merz wrote:
> I ordered from MH Electronics,  one each of replacement crystals
> for a Mackay 3010 receiver in range of 50  to 60 Mhz,  at $15 each. 

Thanks Dan -- I found their web site and bookmarked it.   I did get 
an email back from ICM quoting $15.95/each and two weeks 
delivery so we'll see how that goes.   

At the rate I'm going two weeks won't be any problem at all.  And I 
found a couple of 18 Mcs HC-6 units that can be used if necessary 
to get 80 meters working until the real thing shows up.   CR-18's, 
intended to operate on the parallel resonant frequency but they'll do.

Poking around looking for manufacturer web sites I discovered the 
interesting fact that the quartz stock from which crystals are now 
made is produced by disolving sand in water at 400 degrees C and 
1000 psi (I think those are the numbers ...)   Amazing -- to think 
that at the outset of WW II there was serious doubt about 
converting to crystal control because of the vast quantities of 
natural quartz needed and doubts that we'd be able to import it 
under wartime conditions.  

A very interesting recounting of the influence of hams on the early 
history of crystal control may be found at:

http://www.bliley.net/XTAL/Industry-Hams.html

Something I didn't realize:  The ham market for crystals was many 
times the size of the commercial station market in the immediate 
prewar years.  Many of the companies whose names will be found 
in any under-the-hamfest-table box of junk military crystals were 
already in operation in the late 30's, selling to us.   Bliley, Valpey, 
James Knights, Scientific Radio Products -- and more.  It's hard to 
imagine how the war might have been different had it not been for 
this little-known ham resource, for crystal control down to the 
tactical level was critical to operating the vast numbers of channels 
required by our forces.  

Walt 
KJ4KV