Magnetic Loop antenna

3 Foot Magnetic Loop Antenna Complete	Magnetic Loop ready for test
Test Setup Variable Capacitor control panel and indicator lights Icom740 Transceiver and SWR meter	Initial testing of the antenna
Collins Vacuum Variable Capacitor RF voltages can be extremely high at the capacitor when running over 10 Watts Thus the need for a vacuum variable with remote tuning	Close-up of the DC motor, gear drive and connection method before soldering
Another view of the connection to the loop	Vacuum variable mounting scheme. It came with a nifty silver plated clip for one end
Setting up to solder the loop to one end of the capacitor. The capacitor did not come with any easy way to connect to the other side.	Connecting to the other end of the capacitor. Note the silver-plated clip
Shot of the RF feed and control cable plugs	RF Feed method 1
INITIAL OBSERVATIONS 3 FOOT MAGNETIC LOOP 9/19/16 Test setup: IC-740 with 20 ft RG8 coax to antenna. Remote toggle to run the vacuum cap motor. End of travel LEDs wired. 1-The antenna appears to have good sensitivity, hearing lots of strong signals while tuning around the 10 and 14Mhz bands ~4PM. 2-Sharp but shallow nulls while transmitting 1-2 Watts. 3-SWR still off scale most HF Bands --14Mhz Band-- Running the cap through full end-to-end travel shows a sharp null but SWR still off scale. Noted that low end of 20m band is better than high end. --10 Mhz Band-- (design goal) Running the cap through full travel gave sharp nulls but unable to tune a low enough SWR to operate Could achieve a 4:1 match @ 9900 Khz (low end of band) Cap appears to be mid-range. Could not tune a match at 10559 Khz (hi end of band) --7Mhz Band-- Again seeing extremely sharp nulls while running the cap through its travel. Able to achieve a 4:1 match at 6900 Khz (low end of band) Could obtain a 2:1 match at 7599 Khz. (hi end of band) This was the best match on any freq	Wiring the test control panel view the wiring diagram
Back to Ham Radio Page 09/22/16	Diagram of the Magnetic Loop antenna