Meteor calibration System by Dave Swan (UK)

How to build ?

Take a 50/75 ohm plug and solder one end of a 50/75 ohm resistor to the centre pin and the other end to the outer case.

1. Connect up the system and set the receiver to the frequency in use.

Terminate the receiver antenna input in its Characteristic Impedance, this is usually 50 ohm for professional or scanning receivers and 75ohms for Band 2 FM stereo receivers. Use only carbon resistors not wire wound.

Reset the system and adjust the Threshold controls above and below the displayed Noise level so that the system is not triggered into producing a count. If the system is triggered adjust the necessary threshold to prevent this. When the system is running with no triggering observe for at least 30 minutes to confirm no random triggering of the system.

If random triggering persists the probable cause is man-made noise getting through the power lines or computer hash usually the monitor, fit an appropriate filter.

If an RF Signal Generator is available, see Annex A.

Continuing from 3. Observe the displayed noise level and remove the terminating resistor and refit the antenna, if the antenna is a good match and there is no man-made noise present, you should see no major increase in noise.

Reset the system, and you are ready to start observing.

Changing any of the system components will require system Reset.

This set-up is to ensure that the system itself is not generating false counts!

Annex A: At this point the system sensitivity can be measured.

If any problems occur with this procedure contact: dave@radiodesignservices.co.uk