70cm Magnetic loop version #2

Netherlands,

70cm Magnetic loop - Version #2

Following the first version of my magnetic loop for 70cm (for use on my Standard C-528 HT), I tried and implement some improvements. The result is shown on this page. Using version #1 of the loop, I really felt the loop should gain a little height to minimized the hand-effect from being close to the radio.

Using the same copper pipe I used for the construction of version #1 - 6mm - I cut a piece of 8cm in length and soldered that to the top of a BNC-male connector. I used a piece of PTFE coax to run through the 'mast' up to the loop where the braid got soldered to the top of the copper pipe. I left enough length for the inner conductor to form the coupling loop. Both loop halves were soldered on top of the vertical piece and the variable capacitor was put back in place.


This is the loop sitting op top of the HT with a directional coupler in between to measure the VSWR. I did not solder the inner conductor of the PTFE coax yet, I wanted to find the point of lowest VSWR on the loop circumference first. It proved to be in the middle, where the loop is grounded, resulting in a coupling loop of 10mm. This is exactly the same size I had used in version #1 of the loop.	The loop in detail. The whole contraption is about 13cm tall, easy to use on the HT. Note that the vertical piece has been silverplated :) The measured VSWR 2:1 bandwidth turned out to be 7MHz. When tuned, the loop has a 1.0:1 VSWR.