Bob Monaghan ) writes:

Wasn't there a recent historical article in QST on the role of the quartz
xtal industry in WWII, how they figured out overtone osc. issues and so
on?

Given that some sources ask $12 and up for scanner and ham crystals, these
costs add up rather fast if you need to replace a bunch of xtals in a
scanner. So the search for alternatives seems quite worthwhile ;-)

But they already figured out the solution, thirty years ago, and
it did not require going to the quarry for quartz and digging out
old QSTs. The need for a lot of crystals luckily coincided with
digital ICs, so before most people could get around to paying for
all the crystals to fill out a mult-channel unit, synthesizers came
along so you only needed one crystal. About as soon as it could be
done practically, hams built them and wrote up articles in the ham
magazines.

Anyone who decides to make their own crystals today, other than
for the sake of doing so (and I admit it would be an interesting
thing to try), will likely find they can't go for the subminiature
look, and probably will find that putting effort into building
a synthesizer still makes sense if you need more than a few
crystals.

Michael VE2BVW

"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

Eddie Haskel wrote:

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



No, the good _really_ 'ol days of taking a chunk of quartz, whacking
pieces off of it with a mud saw, hand lapping the saw marks off and
mounting it in a home-made holder. That namby-pamby FT-243 wasn't
invented until just before WW-II.

The same magazine has an article about the blind ham who built his own
equipment. Soldering by feel. There were giants in those days...

--

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

actually, it is a lot easier to simply etch or grind away some of the
xtal, then check it with a grid dip oscillator for sharp dip, no need to
remount and test ;-) An old Hints and Kinks IIRC. This could be really
handy if you wanted to make a xtal filter and needed to really match and
control the xtal freq offsets (what, 3.5179 Mhz xtals from TV color burst
sources?) ;-)

and how about drilling a small hold in the holder so you could tread a
small bolt to put pressure on the xtal holder plates, shifting the xtal
freq. around like a xtal controlled VFO - but only a handful of khz ;-)
Still, very solid (pun intended) freq. source that can be varied around
enough to avoid QRM at minimal cost and effort for QRPers and so on? ;-)

Wasn't there a recent historical article in QST on the role of the quartz
xtal industry in WWII, how they figured out overtone osc. issues and so
on?

Given that some sources ask $12 and up for scanner and ham crystals, these
costs add up rather fast if you need to replace a bunch of xtals in a
scanner. So the search for alternatives seems quite worthwhile ;-)

regards bobm
--
************************************************** *********************
* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
********************Standard Disclaimers Apply*************************

On Mon, 12 Apr 2004 17:41:41 -0700, Tim Wescott
wrote:

H. Peter Friedrichs wrote:
Hello, All:

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.

Remove XXX's and ZZZ's if you wish to reply directly, and thanks.

Pete
AC7ZL



"Cutting Quartz Crystal Plates". QST, January 1935, page 36.
Unfortunately that's from my swiftly-rotting paper issue, and I don't
have a scanner.

Aw, c'mon, Tim. Photocopy and snail it to the guy!

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

H. Peter Friedrichs wrote:
Hello, All:

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.

Remove XXX's and ZZZ's if you wish to reply directly, and thanks.

Pete
AC7ZL



"Cutting Quartz Crystal Plates". QST, January 1935, page 36.
Unfortunately that's from my swiftly-rotting paper issue, and I don't
have a scanner.

--

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

"H. Peter Friedrichs" wrote in message
ink.net...
Hello, All:

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.
Remove XXX's and ZZZ's if you wish to reply directly, and thanks.
Pete
AC7ZL


Pete,

I have my Dad's grinding stuff, but don't do it. One thing to keep in
mind, and I don't know the details, but remember that the crystal activity
is effected by the edges. Grinding the edges is one of the more esoteric
aspects.
--
Steve N, K,9;d, c. i My email has no u's.

Steve Nosko wrote:

"H. Peter Friedrichs" wrote in message
link.net...


Hello, All:

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.
Remove XXX's and ZZZ's if you wish to reply directly, and thanks.
Pete
AC7ZL




Pete,

I have my Dad's grinding stuff, but don't do it. One thing to keep in
mind, and I don't know the details, but remember that the crystal activity
is effected by the edges. Grinding the edges is one of the more esoteric
aspects.


The trick isn't the edges but keeping the two surfaces parallel and
flat. The procedure is to grind a little
and check the activity. If it is down try to grind the center or edges
and check again. If it gets better
then go back to to grinding and trying to keep it flat.

Anyway that is the method I used.

Bill K7NOM

"Bill Janssen" wrote in message
...
Steve Nosko wrote:

"H. Peter Friedrichs" wrote in message
link.net...

Hello, All:
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.
Remove XXX's and ZZZ's if you wish to reply directly, and thanks.
Pete
AC7ZL




Pete,

I have my Dad's grinding stuff, but don't do it. One thing to keep
in
mind, and I don't know the details, but remember that the crystal
activity
is effected by the edges. Grinding the edges is one of the more esoteric
aspects.


The trick isn't the edges but keeping the two surfaces parallel and
flat. The procedure is to grind a little
and check the activity. If it is down try to grind the center or edges
and check again. If it gets better
then go back to to grinding and trying to keep it flat.

Anyway that is the method I used.

Bill K7NOM

Sounds important, Bill, but my words may have been misunderstood. By
edges I meant the end surfaces...as in ; stand the blank up on one edge -
vertically - there are four of 'em. I don't remember if he said that the
ends must be made to have a 90 degree angle with the faces or what. I just
remember that he said that you grind these sides for best / better activity.

I was not referring to the outer reaches of the two large faces as in; is
the face flat or curved in some way.


--
Steve N, K,9;d, c. i My email has no u's.