Many years ago my father (now a silent key) built a crystal tester that
pretty much worked with any crystal you stuck into it. Low frequency,
high frequency, name it. It also had a meter that indicated "crystal
activity" and also had an adjustment (think it was a pot) for IIRC
"bias". Also an output jack to feed say a frequency counter.

I imagine that he got the circuit from either an issue of QST or the
handbook. Searched the web, though I found many circuits, none looked
like this one. Anyone recognize from my sketchy description the circuit
my father used, and any links to where I can get a schematic so I can
build my own? TIA

73s Bob

On Apr 6, 4:49 pm, robert casey wrote:
Many years ago my father (now a silent key) built a crystal tester that
pretty much worked with any crystal you stuck into it. Low frequency,
high frequency, name it. It also had a meter that indicated "crystal
activity" and also had an adjustment (think it was a pot) for IIRC
"bias". Also an output jack to feed say a frequency counter.

I imagine that he got the circuit from either an issue of QST or the
handbook. Searched the web, though I found many circuits, none looked
like this one. Anyone recognize from my sketchy description the circuit
my father used, and any links to where I can get a schematic so I can
build my own? TIA

73s Bob

To check crystals I use an old Heathkit Grid dip oscillator. good
xtal will oscillate, meter will show activity ,tune it in on your
receiver to read frequency. Don`t think the newer GDO (fet osc) will
work as well as the old tube type..I see them at hamfest ,sometimesf
or or a few bucks..GL HS

robert casey wrote:
Many years ago my father (now a silent key) built a crystal tester that
pretty much worked with any crystal you stuck into it. Low frequency,
high frequency, name it. It also had a meter that indicated "crystal
activity" and also had an adjustment (think it was a pot) for IIRC
"bias". Also an output jack to feed say a frequency counter.

I imagine that he got the circuit from either an issue of QST or the
handbook. Searched the web, though I found many circuits, none looked
like this one. Anyone recognize from my sketchy description the circuit
my father used, and any links to where I can get a schematic so I can
build my own? TIA

Pierce oscillator circuit will do what you want, and you should
find it in some editions of the Handbook. I know Hints and Kinks had
an updated version using a MOSFET, but to be honest anything with a high
impedance input and some gain will oscillate that way.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

As Scott said, any amplifier with gain can be used. Generally, oscillators
do not work over infinite frequency range. If you wanted to check out the
low frequency surplus crystals, you built one with a lot more inductance in
the "plate" lead. Most hf crystals will check out fine in a single
oscillator.

I have built some using an fet for gain and a led to indicate current flow.
Although I have some with meters, generally you are looking for a go / no-go
type of indication. Heath grid dip meter works well, but you need to build
a socket adapter.

I built a single fet gate dip meter using an MPF-102 out of the Handbook. I
used an FT-243 crystal socket for the coil. It works great as a crystal
tester and the meter indicates activity. Great to let me know I have a
dirty crystal. Although it does not work on low frequency crystals, it
works well otherwise.

My favorite is one from Ham Radio. It was a solid state oscillator with an
isolating amp for the counter. It has a built in switched capacitors for
change crystal loads and if you plug in an inductor, it will read out in
inductance. I made adapters for various types of crystal sockets.

It reads overtone crystals quite well.

The big problem is sorting out the drawers full of crystals. The
mathematical odds that you will have and can find just the crystal you need
decreases as the number of crystals increases.

Colin K7FM

Doug DeMaw W1FB (SK) developed a "Tester for Crystal F, Q and R" that
appeared in the January 1990 QST (pg. 21) and was reprinted in his
"W1FB's Design Notebook" (pg.192). I just finished building this
project and it works very well. FAR Circuits has a PCB available.

Dino KL0S/4


In article k.net,
"COLIN LAMB" wrote:

As Scott said, any amplifier with gain can be used. Generally, oscillators
do not work over infinite frequency range. If you wanted to check out the
low frequency surplus crystals, you built one with a lot more inductance in
the "plate" lead. Most hf crystals will check out fine in a single
oscillator.

I have built some using an fet for gain and a led to indicate current flow.
Although I have some with meters, generally you are looking for a go / no-go
type of indication. Heath grid dip meter works well, but you need to build
a socket adapter.

I built a single fet gate dip meter using an MPF-102 out of the Handbook. I
used an FT-243 crystal socket for the coil. It works great as a crystal
tester and the meter indicates activity. Great to let me know I have a
dirty crystal. Although it does not work on low frequency crystals, it
works well otherwise.

My favorite is one from Ham Radio. It was a solid state oscillator with an
isolating amp for the counter. It has a built in switched capacitors for
change crystal loads and if you plug in an inductor, it will read out in
inductance. I made adapters for various types of crystal sockets.

It reads overtone crystals quite well.

The big problem is sorting out the drawers full of crystals. The
mathematical odds that you will have and can find just the crystal you need
decreases as the number of crystals increases.

Colin K7FM

"robert casey" wrote in message
ink.net...
Many years ago my father (now a silent key) built a crystal tester that
pretty much worked with any crystal you stuck into it. Low frequency,
high frequency, name it. It also had a meter that indicated "crystal
activity" and also had an adjustment (think it was a pot) for IIRC "bias".
Also an output jack to feed say a frequency counter.


Bob

A simple Pierce or a Colpitts osc. would do the trick. The oscillator
will only work in the fundamental mode. I suspect they
built a simple oscillator, and probably added a germanium
diode (detector) on the output to drive a meter to indicate
the relative "activity" of the crystal under test. I checked
my Bill Orr handbooks and didn't find anything similar.

Pete k1zjh

I have tested crystals on an MFJ antenna analyzer. Watch the needles and
listen with a receiver.

PP

Bob, try searching for this item, you may locate one on an auction site.
SECO Transistorized TWO WAY RADIO TEST SET CRYSTalignMETER MODEL 500. It tests all crystals, various sockets, fundalmental, 3rd overtone,
has R.F. Indicator Activity Meter, Signal Generator function with Modulated & Unmodulated RF, Jacks for Freq Counter connection. Operates on 2-C cells.
I've been using one the workbench since the the 1960's.
73, Don