[Elecraft] K3 Reference Oscillator

[Ian White GM3SEK]

Greg Wrote:

>> Hi Gang:
>> Need help insetting up the TCXO 1ppm oscillator.
>> I was trying to get Method 3 to work in setting up the oscillator.
>> I can get to the menu CONFIG:REF CAL but when I tap  1 I do not get EWF
>> xxC. I assume tap  1 is the #1 key on the key pad? Any help will be great.
>> Ed
>> WA3BZT
>Ed,
>
>Please review your errata sheet that came with the radio.  The firmware 
>is not yet ready for this calibration method.
>

For the record, here is another method for anyone who has an accurate 
10MHz frequency standard and an oscilloscope with X-Y inputs.

1. Set up the 'scope to display a Lissajous pattern in its X-Y mode, 
with sampled RF at 50MHz into the Y input and your 10MHz standard into 
the X input.

2. Set the K3 to 50.000000MHz CW. Key down. You should see a slowly 
rotating 5:1 Lissajous pattern.

(The pattern looks something like
http://www.math.com/students/wonders/lissajous/lissajous.html
with the following user settings:
xFreq = 10 000
yFreq = 50 001
hue Freq - any setting
Samples = 500 or more.
In this simulation, the offset between xFreq and yFreq gives a pattern 
that goes through one complete evolution in about 20 seconds. Click 
yFreq down to 50 000 to freeze the pattern at its current phase 
difference; this corresponds to 'zero beat' between the two 
frequencies.)

3. Use the VFO A knob to 'tune' the CONFIG: REF CAL setting until the 
Lissajous pattern is rotating as slowly as possible. Using this visual 
method you should be able to zero-beat the two frequencies much more 
accurately than by ear  (Method 1). The practical limitation is the 1Hz 
granularity in REF CAL settings.




-- 

73 from Ian GM3SEK