[time-nuts] Small quantity custom crystals
w8nf at yahoo.com
Thu Sep 30 21:36:15 UTC 2010
When I was in the television transmitter biz, we ran 5th, 7th and 9th up to 216MHz using JFET Pierce oscillators. We used the same oscillator for low VHF to high VHF and only changed an LC circuit to make sure the oscillator would "take off" on the correct overtone. Our supplier of choice was Piezo Crystals. Ovenized at 65C and IIRC we used SC cut crystals. Not cheap, but we never had crystal problems. Also, a design engineer at Piezo named Lynn Heischman was always available as a consultant for osc and crystal design, even though we were a small quantity purchaser.
--- On Thu, 9/30/10, Rick Karlquist <richard at karlquist.com> wrote:
> From: Rick Karlquist <richard at karlquist.com>
> Subject: Re: [time-nuts] Small quantity custom crystals
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Date: Thursday, September 30, 2010, 12:12 PM
> Mark Sims wrote:
> > I need to build some small tracking transmitters
> (using a circuit similar
> > to http://www.jbgizmo.com/page4.html
> > This circuit uses a fifth overtone crystal to get an
> output in the 216 to
> > 220 MHz range. The circuit is rather finicky about
> the crystal and
> > transistor... most don't work.
> AFAIK, that is way too high a frequency for 5th
> overtone. Has
> something changed? Are you sure there isn't a
> frequency doubler
> after the oscillator?
> Anyway, you can get a complete synthesizer on a chip from
> Devices that uses very low power (see the ADF4360-8) so
> might want to consider that as an alternative.
> Rick Karlquist N6RK
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