This is pretty standard stuff in the FMT community. In my IC 751, which
have used in the FMT's, I simply placed a small styrofoam "box" around
the ref crystal. It is the temperature induced short term drift that is
the problem, not the absolute accuracy. I can measure where it really
is but it needs to stay there. Any way you can isolate the crystal from
temp changes will help to stabilize it. Some use a plain resistor as a
heater inside the insulation..a la crystal oven. Some just use the
insulation and let the ambient temp do the heating. THe trick is to get
the oven temp above the ambient inside rig temp. Of course, you can use
a $1000 dollar closed loop temperature control also, like the HP
reference ovens. ;)
I'm sure some insulation would help the TR-7.
Curt
KU8L
Jim Shorney wrote:
Some days I am more easily amused than other days.
http://www.k0to.us/HAM/FT1000MP/Temperature%20Stabilized%20FT1000MP%20REF%20oscillator_files/Temperature%20Stabilized%20FT1000MP%20REF%20oscillator.htm
What led me to the above link was a discussion of drift in the IC-706 radios on another
list. It also reminded me of the ongoing discussions on this list of huff-puff
stabilizers for our "drifty" TR-7s. What's new is old, what's old is new.
All kidding aside, this idea might be a good approach to tame those pesky 40
MHz reference oscillators in slaved 7-Twins. I'll have to put it on my round
tuit list.
73
-Jim
--
Ham Radio NU0C
Lincoln, Nebraska, U.S.S.A.
TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A,
HyGain 3750, IBM PS/2 - all vintage, all the time!
"Give a man a URL, and he will learn for an hour; teach him to Google, and he will
learn for a lifetime."
HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
http://incolor.inetnebr.com/jshorney
http://www.nebraskaghosts.org
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