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Re: [KX3] Need Advice - Xmt & Rcv frequencies differ but RIT turned off

Posted by tcollen on Aug 13, 2014; 2:49pm
URL: http://elecraft.85.s1.nabble.com/KX3-Need-Advice-Xmt-Rcv-frequencies-differ-but-RIT-turned-off-tp7592042p7592061.html

Don,

Thanks for setting clearing this up for me.  Very helpful.

Regards,

 Tony


On Wed, Aug 13, 2014 at 8:04 AM, Don Wilhelm <[hidden email]> wrote:

> Frequency stability is normally expressed in terms of ppm over a specific
> temperature range.
> For the KX3 it is +/- 1 ppm over 0 to 50 degC.
>
> I believe the statements below confuse tuning frequency calibration
> inaccuracy with stability - one has nothing to do with the other.
> Problems with the KX3 being consistently off frequency can normally be
> resolved by doing the Reference Frequency Calibration (see the Caalibration
> section of the manual).
>
> 73,
> Don W3FPR
>
>
> On 8/12/2014 3:14 PM, tcollen wrote:
>
>> Hi Jerry,
>>
>> My TS-590 exhibits almost a similar situation, without the SO-3
>> high-stability oscillator installed. The specs say the 590's frequency
>> stability is within +- 5ppm, and I've found the higher in frequency I go,
>> the further up I need to tune to zero-beat a station. On 20m, I've found I
>> have to consistently tune up a bit to center.
>>
>> Doing the math, it looks like your KX3 is at least consistently off by 25
>> or
>> 26 ppm:
>>
>> 133 / 5.0 = 26.6 ppm
>> 190 / 7.335 = 25.9 ppm
>> 250 / 10.0 = 25 ppm
>> 384 / 15.0 = 25.6 ppm
>>
>> 25-26 ppm definitely adds up, and it seems to me the unit is
>> mis-calibrated,
>> but I don't know what the KX3's tolerance for frequency stability is.
>>  I'm a
>> new KX3 owner myself so I haven't had enough experience with it to figure
>> out if my unit is off by a small bit or not.
>>
>> Does the behavior change when the unit has been off for a while, vs when
>> it
>> warms up?
>>
>>
>>
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