[ICOM] 706 MK II off frequency

[Buck - N4PGW]

Thank you, Clete,

I just used the Telephone version of the test.  I was able to put the mic to
the phone over the speaker of the radio and adjust the volume of the radio
so it didn't drown out the phone version.  The phone picked up the
oscillation difference much more quickly than my ear did.  When the tones
were out of synch but close, they phone skipped a bit.  Once synchronized,
it sounded like one tone when I lowered and raised the volume of the radio.


I tried closing my eyes and tuning around until it sounded synchronized
several times.  Each time I ended up dead on 10.000.00o.  My rig has been on
for about 5 hours or so, so it was plenty warmed up when I did the test.

As best I know, I don't have the extra stable crystal installed.

Thank you again,
73 for now,
N4PGW






> -----Original Message-----
> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
> On Behalf Of C Whitaker
> 
> de WB2CPN             2005.07.06
> 
> The frequency error when the 706 is receiving
> can be measured by comparing the audio frequency
> of WWV, when the receiver is in the SSB mode, with
> the WWV signal from a second receiver which in the
> AM mode.  The WWV telephone line, 303-499-7111 can
> be used instead of a second receiver.  Unfortunately
> this method only works for those of us who can pick
> up a decent WWV signal.  Further down I'll tell you
> how to use stations other than WWV.
> 
> If you tune the 706 to WWV, SSB mode, readout set to
> 1 Hz resolution, (See 706 manual Page 1 "Front Panel"
> Item 5, "Tuning Step Switch" for setting 1 Hz), and
> place the speaker to the left or right of you,
> then get WWV on the phone, or tune in WWV AM on a
> second receiver, so that you can hear it
> using your other ear.  You'll be hearing two sources
> of the WWV audio tone; one from the phone or AM
> receiver, and one comming from the 706.  Adjust the
> volume of the 706 so that the levels in both ears are
> about the same.  You, the human, are the comparitor.
> 
> If you vary the 706 frequency slightly you should hear
> a beat between the two audio sources.  You want to
> carefully adjust the 706 so that the beat is close
> to zero, and experiment with that by bracketing the
> frequency on the 706 until you get a feel for where
> the 706 frequency is that produces two audio tones
> that are near-coherence.  I expect the 706 to be a
> few Hz off WWV's frequency, so now you know what you
> 706 frequency error is at that WWV frequency.
> 
> That error can be interpolated to other frequencies
> in that if the error at 10 MHz is 12 Hz, the error
> at 20 Hz will be 24 Hz, and at 5 MHz it will be 6 Hz.
> 
> 
> 73   Clete
> 
> 

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