[DSP-10] Need some help with initial setup

[Roger Hayward]

Greetings.

I'm speculating that the 10 MHz crystal oscillator in the DSP-10 may be
off a little-bit.  This forms the frequency-phase reference for both the
19.68 MHz VCO and the 124 MHz VCO.  My crystal oscillator was off by a
little bit until the reference was tuned in.

C110 (Figure 7 from the September 1999 issue) provides some slight
tuning to Y101, the 10 MHz crystal oscillator.

If you have a frequency counter or an oscilloscope, you can measure the
10 MHz frequency by probing at pin 1 of P106.  If not, a slight
adjustment to C110, followed by comparing against the '897 should do it.

If you haven't swept the full tuning range of the 124 MHz VCO using
UDIAG3, this will be a good thing to confirm.  It is helpful to verify
this VCO will sweep its entire 124 to 128 MHz range.  In addition, it is
useful to verify the 19.68 MHz LO is indeed on-frequency.

See the notes on UDIAG3 for more assistance:

	http://www.nwham.net/ka7exm/dsp10/index.html

73.

	Roger







-----Original Message-----
From: dsp-10-bounces at mailman.qth.net
[mailto:dsp-10-bounces at mailman.qth.net] On Behalf Of John Scherer
Sent: Friday, October 22, 2004 7:01 PM
To: Discussion of DSP-10 2-meter transceiver
Subject: Re: [DSP-10] Need some help with initial setup

Ok, I can't seem to get the radio to tune accurately across the 2-meter 
band.  I'm off by about 5 Khz.  Any thoughts?

Here's the breakdown:

USB test

DSP-10		FT-897
144.120.00 = 144.120.00
147.570.00 = 147.575.15


FM test

DSP-10		FT-897
144.120.00 = 144.115.00
146.520.00 = 146.525.00
147.570.00 = 147.570.00


My reference radio is a Yaseu FT-897 with the TCXO installed.





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