Saturday, March 26, 2011

Frequency Calibration, the Easy Way

Frank, W3LPL has introduced me to a really easy way to calibrate your RBN CW Skimmer or SkimServ. It goes like this.

1. Set a filter on to pass only spots from your continent, and only on 12 and 10 meters. The reason to use these bands is that any error in calibration increases as you go up in frequency.

2. Wait till the time of day when those bands open, and compare the frequency reported by your Skimmer with those reported by others in your area. The vast majority of Skimmers in Europe and North America are accurately calibrated now, so that if your calibration is off it will probably stand out among multiple spots of the same station.

3. Calculate a correction factor by dividing your displayed frequency by the true frequency. For example, if you spot a station at 28005.4, and the majority report 28005.1, then the resulting correction factor would be 1.00001071.

4. Now open either CWSkimmer.ini or Skimserv.ini, depending on which Skimmer software you are using. You can use Notepad for this purpose.

5. See if you have a line that reads "FreqCalibration=....". If you do not, then add that line, with your correction factor from step 3 inserted to the right of the "=" sign. If you do, then multiply the correction factor by the number you find there, and enter the new number instead.

6. Now save your change, close Notepad and close your Skimmer. When you reopen the correction will be added.

7. Recheck your calibration. You should be very close. If you are still off in either direction, repeat the steps in 3-5 above, making sure to multiply this new correction factor by the value already in the .ini file to derive the new FreqCalibration value.

That's all there is to it. Please check your frequency calibration and help us build the RBN's reputation for producing accurate spots for all users.

Thanks and 73,

Pete N4ZR