Using my 6500 as a Frequency Counter

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Need your opinion .. Working on some old radios that require PLL adjusting. It’s calling for a frequency adjustment within 25 hz. I’m not totally confident that my counter is that close, but I know my Flex 6500 is! Has anyone used the receiver as a frequency counter, with source coupled through a small capacitor (for protection)? Best mode to be in, I’m thinking AM?






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WA2SQQ

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Posted 3 months ago

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Ken - NM9P, Elmer

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I would suggest that you use SSB and set filter Low Cut to 0 and tune for zero beat. 

Alternately (Better, but more complicated.) you could use CW and wide filter....Then activate the CW side tone without engaging the transmitter and tune so that the beat frequency between the signal you are receiving and the side tone beat against each other.  If you have musician's ears, and can hear the low frequency beats, you can come within a few Hz, even a 1/4 of a Hz accuracy just by listening to the two tones beating against each other.  It is how musicians and piano tuners get in tune with a frequency standard or tuning fork.

Ken - NM9P
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k3Tim

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Would 'calibrating' the freq counter work?  Use the Flex to transmit a low power signal into a dummy load or the XVRT port, couple to the freq counter and determine the offset == calibration factoer. Then use the counter ad normal except adding in the cal term.
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WA2SQQ

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Two great ideas thanks