Re: RX888 MkI frequency discrepancies in recordings


Larry Dodd
 

I keep a 12 volt fan running in my RX888 receivers at all times to attempt to stabilize the temperature Not unusual for an oscillator to drift at first start up. The drift test should not be started until after it’s up to stable operating temperature.  At least 10 to 15 minutes. 
Larry

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On Sep 11, 2022, at 7:41 PM, D R via groups.io <robsond90@...> wrote:



[Edited Message Follows]

Hi Simon,

I did a drift test earlier, but it turned out to be not very scientific due to both RWM and WWV fading rather too much.  It did, however, reveal that the MkI calibration drifts a lot in the first hour - about 40Hz - but the IF Display errors settle down after about 20 minutes.  I'm going to do a proper test tomorrow using a 10MHz signal from a GPSDO to see exactly how long it takes the unit to fully stabilise (or if it ever does!).

In the meantime, a screenshot of what happens to a 10MHz signal in the IF Display when the waterfall is shifted R - Centre - L in 1MHz hops: the apparent frequency changes in 70Hz steps.  I'll check in the next test whether that step size is temperature related, or whether it's just a function of the waterfall display width.

Regards,
Dave

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