Michael Black wrote:

"Eddie Haskel" ) writes:

Rumor has it that QST featured an article in a January/1930 or

January/1935

issue on the subject of homebrew transmitter crystals - how cut, lap,

and

mount them. If anyone has QST on CDROM for those years, I'd sure

appreciate

if you could take a look.

Ah yes..the good 'ol days of grinding FT-243 Xtals with toothpaste(or
comet)to go up, and writing on the blank with #2 pencil lead to take them
down a few Kilocycles....Eddie



Actually, considering the date of the magazine, they aren't talking
about shifting commercial crystals.

They must be talking about taking quartz, and making crystals. On
the same level as making your own capacitors. I gather it might
have been common back then. Does the date coincide with requirements
of "crystal like" stability? I can't remember when such rules came into
effect, but I can imagine it would have set off homebrewing of crystals.
For that matter, there may not have been that much choice; I have no
idea what the state of commercial crystal manufacturers were back
then. ANd considering it was the thirties, likely many hams had
no money to buy commercial crystals, but they could scrounge.

It was WWII that offered up all those surplus crystals in FT-243 holders.
If you were lucky, some would fall where you needed them. A bit less
luck, and you'd at least find some close enough to your needs that you
could grind them a bit and move them onto your frequency. With no luck,
you'd have to buy crystals.

One could reference the other thread about selecting a receiver's IF
frequency. Often, such selection resolved to what was available. If
you could buy a filter, you'd use that frequency. Likewise when hams
started making crystal lattice filters after WWII, they used frequencies
which were available (which luckily overlapped the common 455KHz IF).
Even today, the choice of frequency for a homemade crystal ladder filter
often depends on what crystals are available cheap. Not the only criteria,
but one of the criterias.

Michael VE2BVW




This was actually just before then, when crystal stability was expected
but not (I believe) required. The '33 handbook "starter transmitter"
was just a TNT oscillator connected to an antenna.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com