Odds are they're both wrong. The Cobra 2000 has two small plastic-housed ceramic trimmer caps. One on the USB carrier crystal and one on the counter's reference crystal.
We routinely find these have oxidized and become erratic. If you tune in the 7.8015 on a receiver set for SSB, you'll hear that scratchiness as the pitch of the carrier tone changes when the trimmer screw is turned. A shot of control cleaner tends to clear this up after it gets twirled all the way around both ways a dozen or so times. Once you can hear a smooth change in pitch from the receiver's speaker when the trimmer is turned, there's a good chance that trimmer will stay set where you adjusted it.
But until this gets done, any effort to adjust it may or may not stay adjusted where you set it.
Pretty much every one of these radios we see have noise you can hear in those two trimmer caps when they are turned.
Getting the external counter calibrated calls for a reference that you can trust. For that matter, if the trimmer cap in the external counter is old enough, it could have this issue as well.
What you need now is a frequency reference of some sort that you can trust to be accurate. No other way to calibrate a counter. Can't remember the frequency of the reference crystal in that counter. HP counters will have a socket for using an external reference clock. We found that the 1 MHz internal clock would leak into this socket. Hooking it to a "T" connector, a receiver that can tune in WWV and the antenna gave us a beat note between WWV's carrier and the clock frequency leaking out of the counter. Setting the counter's trimmer cap to zero beat with WWV would put those counters back in calibration.
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