Remember your soundcard may have a frequency offset in it too.
-Dan N7NMD
Jim Reid wrote:
>Hi,
>
>Posted the following about 90 minutes ago, after the
>radio had been ON for about 90 minutes at that time.
>
>
>
>>Sitting here now watching the accuracy of the Orion sub
>>rcvr, using the method George, W5YR described earlier
>>today. At turn on, the indicated inaccuracy was about
>>-17 Hz, as the rig warmed, it drifted upwards reaching to
>>about + 20 Hz. Now after about 90 minutes, the reading
>>is 1027.0, or 27 Hz high. Am going to let this run on
>>for a few hours.
>>
>>
>
>For the last hour+, the indicated MixW signal is at 1026.5 Hz.
>The rig is set to LSB, and the tuning reads 10.001.000, or
>1 kHz above WWVH.
>
>So, I take it via George's method, my readout is 26.5 Hz too
>high.
>
>The Orion's two receivers are coherent in that a single frequency
>reference is used. It is a temperature-compensated crystal
>oscillator (TCXO) that drives both the sub receiver's phase-
>locked loop (PLL) and the main receiver's direct digital
>synthesis (DDS) LO.
>
>Presumably then, both rcvr's indicated frequency readout's
>are high by this same amount. Of course, by ear, when I
>return the rcvr mode to AM, I can tell no change in the signal
>whatsoever with the RIT moved + or - 20 or 30 Hz.
>
>
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