<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000066" bgcolor="#FFFFFF">
Hi Brian,<br>
Thanks for sharing your experience concerning the freq jumping of
the internal 10MHz tcxo.<br>
I have done some research for the 10MHz tcxo (FOX924b) that is used
and have come to the conclusion <br>
that is a low-cost one, with not very high spec's<a
href="http://www.foxonline.com/pdfs/fox924.pdf">
http://www.foxonline.com/pdfs/fox924.pdf</a>.<br>
So first thing I will try is to replace it with an other one, I
think maybe the CFPT-9301 ( <a
href="http://www.farnell.com/datasheets/43326.pdf">http://www.farnell.com/datasheets/43326.pdf
</a>)<br>
It has better temp stability then the FOX924b and the fase noise
spec's in it's data sheet.<br>
<br>
Bert<br>
<br>
<br>
<a href="http://www.farnell.com/datasheets/43326.pdf"></a>
<blockquote
cite="mid:CAE3hgTeZDKhSxiNK1SdnBc-P1o3hs1E=hcNtQ5TMvx0RUBKn6Q@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="HOEnZb">
<div class="h5">
<br>
</div>
</div>
<br>
<div text="#000066" bgcolor="#FFFFFF">
<div>Hi Helmut,<br>
<br>
Yes I know this 'buffer' does clamp the ref. input
between 0 and +/- 3.5V.<br>
I did try to change R142 to 120Ohm, then I get a kind
of symmetrical 10Mhz square wave @+/-2tt, out of my
sinus wave 10MHz.<br>
But unfortunately that did not cure the jumping in
freq, with the external 10Mhz standard. <br>
Yes that 10Mhz standard is stable and does not show me
that jumping.<br>
I almost start to believe there is a FGPA firmware
problem some how not looking correct to the 10MHz
reference all of the time....... <br>
</div>
</div>
</blockquote>
<div><br>
</div>
<div style="">I spent a month or so on this problem with
Apache Labs and with Phil a couple of months ago. Phil
spent a LOT of time trying to figure it out. Like you I
proposed that there might be a problem with the DPLL as
coded into the FPGA but after extensive review and
testing, Phil determined the DPLL is working properly. He
finally determined that the problem is *definitely* the
10MHz internal reference. It is quite easy to hear the
frequency jumps if you listen to a high-order harmonic of
the reference oscillator. The problem does not appear when
the 122.8MHz clock is free running. It appears that the
problem has to do with the digital temperature correction
of the reference oscillator. It stays well within its
specifications even with the frequency jumps, but the step
function used for temperature correction is *REALLY*
annoying. The whole process got Apache Labs looking for a
better 10MHz oscillator that uses analog temperature
compensation. Abhi told me that my 100D was being shipped
to me with a different 10MHz reference and my preliminary
tests have shown that the frequency steps are gone on the
100D. I don't know but I presume that they are using this
new reference on new production radios. </div>
<div style=""><br>
</div>
<div style="">As for the problems with the external
reference input, I experienced those as well too. Changing
R141 solved the problem. I am now using my LPRO-101 Rb
reference without difficulty or problem. Because of the
frequency jumping I now use the Rb reference 100% of the
time with my ANAN-10. </div>
<div style=""><br>
</div>
</div>
-- <br>
Brian Lloyd, WB6RQN/J79BPL<br>
706 Flightline Drive<br>
Spring Branch, TX 78070<br>
<a moz-do-not-send="true" href="mailto:brian@lloyd.com"
target="_blank">brian@lloyd.com</a><br>
<span><span id="gc-number-9" class="gc-cs-link" title="Call
with Google Voice">+1.916.877.5067</span></span><br>
</div>
</div>
</blockquote>
<br>
</body>
</html>