An interesting technique used many places including HP is to have
a radio receiver connected to a pickup coil in the vicinity of
the grinding machine. The vibrations of the abrasive wheel
cause "pings" in the receiver at the resonant frequency. It
doesn't seem like this would work, but it reportedly works
quite well.
Rick N6RK
On 6/20/2013 5:47 PM, Bob Camp wrote:
Hi
Crystal processing is typically monitored either by time or by frequency shift.
Grind in this lap powder for xxxx frequency change. Etch in xxxxx stuff for 30
seconds. Different factories do it different ways. The ones that I am familiar
with seem to mostly monitor by frequency change.
Bob
On Jun 20, 2013, at 7:57 PM, Gary <n...@lazygranch.com> wrote:
A common scheme in metal deposition measurement is to measure the frequency of
a crystal prior to starting the deposition process, then monitoring the
frequency shift of the crystal as the metal is sputtered.
I was told crystals are tuned this way at the factory, but don't know this for
a fact.
"Burt I. Weiner" <b...@att.net> wrote:
Brian,
I remember grinding FT-243 crystals. I had a TV set safety glass
about 18" square and about 1/4" thick. That and some Comet type
cleanser mixed with water to make a thin paste would work wonders. I
was taught to put my finger on the corners and grind an equal amount
on the 8 corners (4 on each side) so as not to remove the bevel of
the quartz. Once I applied this lesson I was able to grind crystals
that were more stable and more active. When I over-leaded them I was
generally able to remove the lead using alcohol. I've still got the
old TV safety glass although it has an area near one corner that is
very opaque do to all the grinding that was done in that area. Those
were fun days!
Burt, K6OQK
From: Brian Alsop <als...@nc.rr.com>
Reminds me of the FT-243 xtal controlled transmitter Novice days.
Xtals
of the frequency you wanted were hard to come by. We would grind
xtals
a bit on a bed of very fine abrasive to raise their frequency.
The other trick was taking a pencil and adding graphite to the xtal
faces to lower it's frequency. You couldn't add too much or it would
stop oscillating-- forever. Never did understand the forever part.
Removing the graphite didn't bring it back to life.
Brian
K3KO
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
b...@att.net
www.biwa.cc
K6OQK
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