[TenTec] My Orion's "Dial" Accuraccy

Dan n7nmd at arrl.net
Wed Jun 4 15:59:11 EDT 2003


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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>
>  
>





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