Delta Loop - Revisited
When I did my last transformer for the Delta Loop, I used a 4:1. It was pretty good. But it was too much transformation. I decided to rebuild a 2:1 transformer and it proved to be a much closer match.
The Transformer
I used my same cutting board balun test setup that I used for the 4:1, except this time I used binding posts I got at our last Swap Meet. This is much nicer for testing than wingnuts, especially when you need to adjust wires. I did have to trim a couple inches of wire to tune it up and lower the top height of the loop down a section on the mast. The core is the same Type 61 {Size: 1.400” (35.56mm) OD. Core: 5961002701}. I set it up in the backyard for a quick test n’ tune.
NanoVNA
The sweeps were good and a noticeable improvement over the previous 4:1 build. This reinforces the idea that loop antennas are indeed around that 100 ohms or so mark. The 2:1 transformer is bringing it down to around 50 ohms resistive with a smidgen of reactance. Not too shabby at all. When I used the 4:1, it took it down to around 30 ohms which proved to be too much transformation. The 2:1 ratio is baby bear’s porridge - just right!
Conclusion
This is a step in the right direction for the Delta Loop antenna. If I build more loops going forward, we are going to use the 2:1 as a benchmark and go from there.
POTA Activation Results
This POTA Activation got cut short due to a dead battery that I thought was charged… ug. 26 Contacts in about 27 minutes and exceptional audio. This is a very clear and quiet antenna! It was positioned running East-West so that South was perpendicular to the loop (broad side). The pattern is interesting with no straight East or West contacts, possibly indicating a bit of a null off the ends.
POTA Activation Results 2
I went back for revenge after the previous battery debacle. With a fully charged battery I got 107 contacts in 1.5 hours, including some nice DX Contacts. The map goofed the location because the TransCanada Trail defaults to Newfoundland. But I was operating from Moose Jaw, SK for this activation. World Radio League wouldn’t let me change it for some reason. Very even coverage for the contacts with a noticable cluster into Illinois!
73 de VE5REV