Crystal info needed... - Electronic Circuits Projects Diagrams Free

captainkirksdog · 23rd March 2005, 09:02 AM

Hi all,
Does anyone have any info on how to "fake" a specific frequency crystal?
I need a 14.00000MHz rock and I can't afford to have one made. Prices on custom crystals have jumped over 4000% in just the last five years. So, is there a way to take some other frequency, do some circuit magic, and stuff it where it's needed? Thanks.

fredsm · 23rd March 2005, 09:27 AM

Why "fake" it?
Old PeeCee mainboards have salvageable assemblies.
14.318 MHz was a common frequency.

Mouser has HC-49/U AT-cut 30ppm rocks for US $0.40 -
much cheaper than they used to be.
And a CSA-309 type at 28 MHz at US $0.83 that could
be used with a /2.

The parts needed to construct a tuned oscillator, although
easily done, would cost more than a crystal, and be much
less stable and more temperature sensitive.

<als>

**Nigel Goodwin** · 23rd March 2005, 09:56 AM

Yes, there are lots of alternatives, such as using a PLL locked to a higher (or lower) frequency crystal.

But a lot depends what you want the crystal for?, isn't 14MHz an amateur band? (or at least part of it).

captainkirksdog · 25th March 2005, 07:28 AM

Quote:

But a lot depends what you want the crystal for?, isn't 14MHz an amateur band? (or at least part of it).

Hi,
Yes, I believe you are correct, but I'm not using it for that. I have a SW converter that outputs to an old AM radio. It has a 1.00000MHz offset, and since I already have 2.5, 5 and 10MHz time signals from WWV on it, I wanted to get 15MHz, too. I don't want to have to fool with it too much, so obviously, the best way would be a 14.00000MHz crystal. Any thoughts?

**Nigel Goodwin** · 25th March 2005, 08:12 AM

Quote:

Originally Posted by captainkirksdog

Quote:

But a lot depends what you want the crystal for?, isn't 14MHz an amateur band? (or at least part of it).

Hi,
Yes, I believe you are correct, but I'm not using it for that. I have a SW converter that outputs to an old AM radio. It has a 1.00000MHz offset, and since I already have 2.5, 5 and 10MHz time signals from WWV on it, I wanted to get 15MHz, too. I don't want to have to fool with it too much, so obviously, the best way would be a 14.00000MHz crystal. Any thoughts?

In that case, how about a 14.318MHz crystal? - these are standard and freely available. It would move your converter output to a different frequency though.

If that isn't possible, use a PLL and lock a free running VCO to a different crystal frequency - say 1MHz, with divide by 14 from the VCO to the phase comparator.

fredsm · 25th March 2005, 12:27 PM

A converter covering that range will almost
certainly include switch-selectable tuned
circuits for the particular band. Changing
the injection frequency will not be the only
modifications necessary. Find an old ARRL
Radio Amateur's Handbook; there used to
be (and probably still are) circuit examples
for WWV converters for 5/10/15/20 Mhz.
<als>

23rd March 2005, 09:02 AM	(permalink)
captainkirksdog Experienced Member	Crystal info needed... Hi all, Does anyone have any info on how to "fake" a specific frequency crystal? I need a 14.00000MHz rock and I can't afford to have one made. Prices on custom crystals have jumped over 4000% in just the last five years. So, is there a way to take some other frequency, do some circuit magic, and stuff it where it's needed? Thanks. __________________ <ckd> "Chance favors the prepared mind."--Louis Pasteur (1822 - 1895)

23rd March 2005, 09:56 AM	(permalink)
Nigel Goodwin Super Moderator	Yes, there are lots of alternatives, such as using a PLL locked to a higher (or lower) frequency crystal. But a lot depends what you want the crystal for?, isn't 14MHz an amateur band? (or at least part of it). __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

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23rd March 2005, 09:27 AM	(permalink)
fredsm Experienced Member	Why "fake" it? Old PeeCee mainboards have salvageable assemblies. 14.318 MHz was a common frequency. Mouser has HC-49/U AT-cut 30ppm rocks for US $0.40 - much cheaper than they used to be. And a CSA-309 type at 28 MHz at US $0.83 that could be used with a /2. The parts needed to construct a tuned oscillator, although easily done, would cost more than a crystal, and be much less stable and more temperature sensitive. <als>

25th March 2005, 12:27 PM	(permalink)
fredsm Experienced Member	A converter covering that range will almost certainly include switch-selectable tuned circuits for the particular band. Changing the injection frequency will not be the only modifications necessary. Find an old ARRL Radio Amateur's Handbook; there used to be (and probably still are) circuit examples for WWV converters for 5/10/15/20 Mhz. <als>