[Lowfer] HC-49 Crystal on 1856 khz

[Bill Ashlock]

Lee,

Another advantage to your Xtal approach is that you can add FM modulation to that Xtal osc by simply connecting a series 2pf - 5pf cap to the hot side of the Xtal and a GP rectifier diode to gnd (cath to cap) at the other end of the cap. The modulation is applied via a ~1 meg series resistor to the diode. The diode acts as a poorman's varricap but you will find there is plenty of freq change on a typical QRSS30 screen with a simple 1N400X and will likely have to increase the value the resistor to keep it under a deviation of 1Hz.

Bill

> From: pulsarxp at embarqmail.com
> To: lowfer at mailman.qth.net
> Date: Thu, 5 Aug 2010 20:14:17 -0500
> Subject: [Lowfer] HC-49 Crystal on 1856 khz
> 
> A short while back I ordered some parts from Dan's Small Parts and Kits. 
> Among other things, he has HC-49 crystals on 1856 khz.  The price is 
> 5/$1.00.  I ordered 5.  They look great but I have not tried them.
> 
> I was thinking, if you want to make a Lowfer transmitter without an Epson 
> osc, you could use one of these crystals into a divide bye 10 chip and come 
> out with a Lowfer freq signal.  You can hardly beat 5 for a buck.
> 
> Lee, w0vt
> 
> 
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