Gerard:
Bob Larkin has a number of good tuneup procedures for these PLL's, along
with suggestions on what to do here. Check out his web page, and
suggestions from N7HPR's assembly procedure as well.
I found that it was most-useful to break the PLL from the VCO, and make
sure you could tune the VCO without the PLL pulling on the circuit any.
I replaced the tuning voltage of the PLL with a variable resistor.
Tuning the resistor, I could check the range of the 124 to 128 MHz VCO.
Once I was satisfied that the re-tuning of the circuit would lead to a
decent tuning range, I re-introduced the PLL.
Please feel free to refer to my notes on the website:
http://users.easystreet.com/rhayward/dsp10/index.html
and
http://users.easystreet.com/rhayward/dsp10/pll_tuneup.html
You will probably have to perform some re-tuning to both VCO's in order
to get their specified range to operate within the center-voltage from
the PLL.
73,
Roger Hayward
ARS KA7EXM
-----Original Message-----
From: dsp-10-admin@mailman.qth.net [mailto:dsp-10-admin@mailman.qth.net]
On Behalf Of G=E9rard Parat / F6FGZ
Sent: Sunday, January 04, 2004 2:23 PM
To: dsp-10@mailman.qth.net
Subject: [DSP-10] PLL problems
Hello,
HNY 2004 !
To begin this new year with a good news, my kit is complete. The
adjustment
procedure has just started and I have some trouble with U104. The
locking range
is around 113 MHz (FREQ sent with UHFA.EXE) with L102 at middle, far
away from
the 126 MHz. I assume to have all the last mods since I review the web
site
with the kit I purchased one year ago.
The second PLL is running around 16 MHz (unlocked) so it seems to have
the same
desease :)
My guess is that the 10 MHz Xtal is not at 10 MHz but I haven't done an
accurate measurement because of the lack of a counter. I'll try tomorrow
to do
this. Anyhow, if someone had already seen this problem, any hint is
welcome
--
73 G=E9rard F6FGZ
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