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<DIV><FONT face=Calibri><FONT face="Times New Roman">My Apache Labs
Hermes/Anan-10 has, what looks like, frequency instability or<BR>drift that
seems to be caused by temperature changes.<BR><BR>I use an external GPS
disciplined 10 MHz reference oscillator. The internal<BR>Hermes reference
oscillator is not functional due to jumper selection. The </FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">GPSDO is turned on 24/7 and
all diagnostic software shows the unit is</FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">functioning flawlessly. It
is an HP 58503A. The disciplined 10 MHz </FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">oscillator is so close to
standard, the difference is measured in parts</FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">per billion. I am quite
sure the 10 MHz signal from the GPSDO is </FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">on the money. I peat this
with WWV and watch the phase. <BR><BR>I first noticed that the receiver
calibration was off each time I checked it so<BR>I studied the
problem.</FONT></FONT><FONT face=Calibri><FONT face="Times New Roman"> I
use WWV as my calibration standard. Calibration</FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">is off when cold
by .100 Hz roughly.</FONT></FONT><FONT face=Calibri><FONT
face="Times New Roman"> To begin I note the external
(skin)</FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">temperature of the case
using an infrared thermometer. The tests </FONT></FONT><FONT face=Calibri><FONT
face="Times New Roman">start at switch </FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">on, skin temperature 66
degrees F and a frequency correction factor of</FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman">.9999977100000. I view
Phase 2 and adjust the dot rotation until it<BR>slows to a crawl. Almost
instantly the calibration starts to shift.<BR><BR>After one hour the skin temp
rises to 92 F and correction factor is now<BR>1.000003125.<BR><BR>After two
hours skin temp is 101 F and correction factor is 1.00000327.<BR><BR>At hour 3
and 4 the skin temperature stabilizes at 103 F and the correction<BR>factor
stays steady at 1.00000327 nominal.<BR><BR>All tests taken with one receiver and
no transmit activity. Highest skin temp<BR>area found on the right side of the
box facing the front.<BR><BR>I have a small fan for peace of mind when using a 4
watt carrier. No fan was<BR>used during these tests. No air obstructions. No
heat source below the radio.<BR><BR>My questions are, what might be causing this
problem and can it be
corrected?<BR>Thanks!<BR><BR>Mike</FONT><BR><BR><BR></DIV></FONT></BODY></HTML>