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Old August 22nd 03, 11:47 PM
arnold russell worthington
 
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Default Service Monitor Calibration Question

You could try tuning in a broadcast station. They are generally very close
in freq. I use a GPS based 10 mhz reference. Calibration of deviation is
more difficult but setting up known deviations with a good fm signal
generator and a spectrum analyzer using bessel zero or carrier null method
will produce very accurate deviations without the need foe another deviation
meter to compare with

Russ - WA4POD

Richard W. Solomon, W1KSZ wrote in message
...
How do you go about calibrating the frequency accuracy of your Service
Monitor ? I know I could go to a local Cal Lab and pay the price, but
I like the idea of doing it myself. I do not service and commercial or
Public Service radios, only HAM so the critical nature of accuracy is
not that severe.
One idea a friend had was to set the Monitor to receive and pick a
signal off the air. He suggested the Mass. State Police as they are
locked to GPS (according to him) or one of several paging systems that
he said were also locked to GPS.
That seems to be a good idea, especially since you are looking at
freqs in the 800-900 MHz region. Of course, one needs to know the
absolute frequency, just being locked to GPS is meaningless unless
they really are "on freq".
Curious what other folks do.

Thanks, Dick, W1KSZ




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Old August 23rd 03, 12:19 AM
KLØS
 
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Some service monitors will accept an external frequency reference, usually
10 MHz....my IFR 1500 has a port on the back that accepts a 10 MHz
signal....I use a pair of HP Z3801A GPS frequency references to drive the
IFR and several other pieces of test gear on the bench.

Dino KLØS/4

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Old August 23rd 03, 08:50 PM
arnold russell worthington
 
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I am the one who suggested using a broadcast station in lieu of a local std.
WWV or CHU would be considered such a station. Earlier today I was looking
through n IFR 1200A maunal and they recommended just such a procedure by
loosly coupling the 10 mhz time base outpot intp the ant port along withan
antenna so as to pick up WWV and adjust the time base for zero beat.
you would need a good stable signal free of fades for best results
Russ - WA4POD
C.L. wrote in message
...

"Richard W. Solomon, W1KSZ" wrote in message
...
How do you go about calibrating the frequency accuracy of your Service
Monitor ? I know I could go to a local Cal Lab and pay the price, but
I like the idea of doing it myself. I do not service and commercial or
Public Service radios, only HAM so the critical nature of accuracy is
not that severe.
One idea a friend had was to set the Monitor to receive and pick a
signal off the air. He suggested the Mass. State Police as they are
locked to GPS (according to him) or one of several paging systems that
he said were also locked to GPS.
That seems to be a good idea, especially since you are looking at
freqs in the 800-900 MHz region. Of course, one needs to know the
absolute frequency, just being locked to GPS is meaningless unless
they really are "on freq".
Curious what other folks do.

Thanks, Dick, W1KSZ


As one other party suggested, Broadcast Radio Stations are pretty

accurate.
Used to be - they were referred to most in any literature for such things

as
Home Built Kits from Eico and so on, as to their Signal Generators to get
them close to accurate. Also, another method no one pointed out, which can
be done with an antenna on the unit, is to pick up the WWV signals on 5,

10,
15 MHz (the ones most easily picked up) also there are others. 7.335 CHU
Canada is one. They are all very accurate and MANY places use them as Time
Base Frequencies. So give them a whirl and see what happens. Personally -

I
would use them far quicker than any 2 way radio signal. C.L.






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