[DSP-10] DSP-10 15kHz off frequency

Wed, 30 Apr 2003 21:14:31 -0700

Tyson:

I was expecting one of the real experts to chime in today at some point.  In
lieu of that.....

Have you done any checking on any of the sub-systems themselves?  For
example, is the 19.68 MHz PLL actually running at 19.68 MHz?  Is the 124 -
128 MHz oscillator giving you the frequency you expect?  If the 10 MHz
oscillator is off by a little bit, this can in essence amplify to perhaps
the 15 KHz offset you are seeing at 2m.

My first hunch / guess would be to examine the 10 MHz oscillator and make
sure it is on, either with a frequency counter or an oscilloscope (it will
be easier with a counter).  Measure on or around R150, and adjust C110 until
you see 10.000 MHz (the closer the better).

For the 19.68 MHz PLL, you should be able to see this frequency at U8 pin3,
or U9 pin 3.  The tuneable PLL should show 124 MHz at U105 pin 3.

See Bob's web page for discussions on how to download code into the EZKIT to
set the PLL's to a given frequency for tuning purposes.  I have a couple of
programs of this sort as well at
http://users.easystreet.com/rhayward/dsp10/index.html that might be of some
use.

Hope this helps you out.

72.
	Roger Hayward
	ARS KA7EXM

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Tyson Baker
Sent: Wednesday, April 30, 2003 1:14 PM
To: [email protected]
Subject: [DSP-10] DSP-10 15kHz off frequency

I have the dsp-10 assembled and working, but it is 15kHz off frequency  (too
low).  Initially, I substituted the less expensive epson crystal and it was
slightly off so I purchased the international crystal one.  That hasn't
fixed the problem.  Anyone have a suggestion as to why it would be 15kHz off
frequency in all modes tx&rx?  I think I have the pll's tuned to spec and
the radio seems to work fine (USB has amazing sound).

Thanks,

Tyson - W5TJB

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