Page last updated 06 Jul 2006

ATS3 Calibration Procedure

Almost everyone has a computer and receiver these days. This calibration procedure requires a receiver capable of receiving WWV at 10MHz and a computer to receive the audio. Using Spectrogram, Spectran, baudline or equivalent you can calibrate the frequency and offset pretty accurately. A noise generator can be helpful or just a noisy band.

Prestep: Peak the IF transformer for peak noise. (Use noise generator if you have one or just a wire connected to the antenna connection. This is for the ATS-3 only)

Step 1: Tweak the trimmer cap on the ATS main board to position the filter shape to where you want it. (Generally centered around 600Hz and a noise generator helps). Do this with the audio from the ATS rig connected to the computer and spectro program.

Step 2: Connect the receiver audio out to the computer audio in and start up your spectro program (free shareware version of Spectrogram 5.17 available at www.n0ss.net ). Tune the receiver to 10MHz WWV and set the carrier of WWV to 600Hz (606.8Hz is the actual sidetone on ATS rigs with my firmware) on the spectro display. A general coverage receiver works FB!

Step 3:  Put the ATS rig in calibration mode "CF". With a short wire (3"-12") on the appropriate test point (TP1) you should see a signal on the computer screen. Click the tune up/down buttons till the new signal matches the WWV carrier. In CF mode the rig will broadcast a near 10MHz signal from TP1. If your receiver is unshielded or is fed by a non-coax fed antenna, your receiver should pickup the tone broadcast via TP1. With the up/down buttons on the ATS rig, superimpose TP1's signal on top of the previously set tone of WWV. Do not power down the ATS rig, but go to the next step.

Step 4: With power still on, connect the ATS rig audio out to the computer audio in and click the menu button to activate CO mode. Move up/down buttons to center the tone on the previously chosen frequancy. Once tone is centered click menu and you are done. You can easily tell what freq to use by keeping your ATS audio connected to the computer and letting the rig send audio (click menu once so that the freq is announced). The screen will tell you what sidetone the rig is using.

Now your freq is spot on and your offset is such that if you hear a station at 600Hz you will be right on top of them (zerobeat).

FAQ

Is peaking at PIN 1 while in CO mode necessary? 

You will notice that the peak for Pin 1 in CO mode is very broad and I would rather my offset match my sidetone to make zero beating easier than be perfectly peaked. Use the BFO trimmer cap to center the bandpass filter on your sidetone of interest using baudline or Spectrogram (Step 1).