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Author Topic: Rig Frequency Reading Vs Tuner Frequency Reading  (Read 788 times)
W3AGT
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« on: February 28, 2013, 03:35:56 PM »

 Running Yaesu FT-100 100 Watts no amplifier using an MFJ-993B Auto Tuner.

I notice a difference in the frequency the rig reports and the tuner.

For example: transmitting USB on 14.280.000 (rig) shows as 14.281

Now if I set the freq to 14.279.30 and transmit voice on USB the MFJ tuner shows 14.280

This differential happens on all freqs and all modes including digital irregardless of power settings.

I'm not having any issue with my qso's and the reports I get are almost always good so I'm wondering if I should be worrying about anything.

Huh

Al
W3AGT
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I am the King of My Castle When the Queen Lets Me
AB1MN
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« Reply #1 on: February 28, 2013, 03:43:03 PM »

Well, when transmitting on SSB (USB or LSB), there is no carrier for the frequency counter to count. When you talk, the transmitter will output a range of frequencies and it sounds like the tuner is displaying something based on the voice input. What do you see when in tune or cw mode?

Also, keep in mind that the frequency counters derive their clock from an oscillator and there will be some tolerance that will affect the accuracy of the readout. Maybe another possibility?

Bob, AB1MN
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KE6EE
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« Reply #2 on: February 28, 2013, 03:44:24 PM »

You can calibrate the frequency counter of the tuner to indicate the same as the frequency of your transceiver. See pg. 31 of the tuner manual.
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K2DC
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« Reply #3 on: March 01, 2013, 03:29:07 AM »

Al,

  Keep in mind that you rig is displaying the frequency of the suppressed carrier, and on USB all of the modulation occurs above that frequency (which your tuner is detecting and displaying).  You may be able to calibrate the tuner to display the same number as the rig for USB.  But if you do that, the minute you switch to CW or LSB, they will show different frequencies again.  I'd leave the tuner cal alone.

73,

Don, K2DC
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AC2EU
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« Reply #4 on: March 01, 2013, 06:18:02 AM »

switch to cw mode and check the frequency readout with the key down.
If they are different, then you have an issue.
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W3AGT
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« Reply #5 on: March 01, 2013, 08:45:29 AM »

Thanks to all for the great advice and tips.

Really appreciate it.

Al
W3agt
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I am the King of My Castle When the Queen Lets Me
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