This week I created a simpler lighter PEX wideband loop. It has half the weight and better stability than my first version. Looks better, too.
Last weekend, I erected my first outdoor wideband receiving loop. With mostly plastic construction, the one meter loop included a vertical PVC brace and weighed in at around 1.2 pounds. In addition, my amplifier was mounted vertically in a box at the base.
I found this version to be a bit heavier than desired and also somewhat top heavy. That got me thinking that perhaps I could streamline my approach by removing the PVC brace and just using a plain loop of aluminum core PEX. So, that’s what I did.
First, I designed a new base box / amplifier enclosure, shown above. Now, the LZ1AQ amplifier is mounted horizontally. This has the benefit of reducing the distance between the ABS mounting pipe and the PEX loop down to about an inch. Lower center of gravity.
Second, I reduced the PEX holding hole diameter in the 3D printed base. Now a plain PEX loop has a tight friction fit with the base and I no longer need the vertical PCV brace. Weight reduction of nearly 50%.
Works great. But I will have to wait for some high winds to see if this simpler lighter PEX wideband loop holds up from a structural point of view.
Simpler Lighter PEX Wideband Loop – Early Results
Performance is good up to 10 MHz with the loop mounted on the chain link fence beside my house. I can even get a good null on neighboring interference from across the street (halogen light power supply.)
But my setup in the shack needs big improvements. I need better shielding in the control box to reduce local RFI, especially from my wireless router. Signal strength seems good from the loop compared to my “real” antennas. But local RFI proliferates.
The loop is connected to a linear power supply feeding 12-13 volts, and the LZ1AQ amplifier is drawing about 150 mA, so that’s good. But the CAT signal pair is just connected to an RG6 patch cord going to my Perseus receiver.
The local RFI is constant whether I turn the loop amplifier on or off. So, that needs to be fixed up as I go along.