[ARC5] Crystal Tester

[Fuqua, Bill L]

  If you look at some of the military crystal impedance meters the usual way they work is by having a tuned non-inverting amplifier with a crystal
in series between the input and output. This makes the crystal oscillate in the series resonant mode. The current is measured thru
the crystal and then you can substitute a resistor for the crystal, not changing the frequency of the amplifier, and adjust the resistor until
you get the same current. This  is the series resistance. 
  You can measure the frequency with a counter. And the if you can measure the Q you can calculate all the other parameters such as 
the motional inductive and capacitive reactance. 
  I have an old military crystal impedance meter but now  use by digital ones. 

73
Bill wa4lav

________________________________________
From: ARC5 [arc5-bounces at mailman.qth.net] on behalf of Richard Knoppow [1oldlens1 at ix.netcom.com]
Sent: Monday, June 13, 2016 1:20 AM
To: arc5 at mailman.qth.net
Subject: Re: [ARC5] Crystal Tester

    There must surely be instruments which will do this. An ordinary
Boonton Q-Meter would not without some help since it will measure Q up
to about 1000 and crystals have Qs of perhaps then times this or more.

On 6/12/2016 10:07 PM, Fuqua, Bill L wrote:
>    What is needed is a simple measurement of series resistance and Q.
> 73
> Bill wa4lav
>
> ________________________________________
> From: ARC5 [arc5-bounces at mailman.qth.net] on behalf of Kenneth G. Gordon [kgordon2006 at frontier.com]
> Sent: Sunday, June 12, 2016 10:49 PM
> To: Arc5 at mailman.qth.net
> Subject: Re: [ARC5] Crystal Tester
>
> On 12 Jun 2016 at 21:37, Robert  Eleazer wrote:
>
>> Also crystal tester articles in 73 mag, August 1996 and Nov 1971.   The Aug 96 article
>> includes some advice on how to restore FT-243 crystals to operation.
>
> Both of those are solid-state circuits with voltages and currents too low (IMHO) to
> adequately test FT-243 or other large crystals.
>
> But thanks for the links anyway.
>
> Ken W7EKB
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--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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