I got some toroids in from Mouser today.
Not happy with the need for an antenna tuner, I decided to gut one of my 9:1 EARCHI antennas and put in a new 49:1 UnUn using a different 43 mix ferrite that people have said is good to use instead of the FT 240-43.
I had a hard time winding the toroid because the hole was smaller. So instead of crossing over 1/2 way through, I kept going.
After re-drilling since I was putting in slightly larger M5 hardware, I dry-fitted everything, bent the wires into place, then removed everything and used a sanding wheel on my Dremel to remove the enamel off the ends.
All the hardware is identical in every way to my existing 49:1 except this plastic case is different. Same wire, same capacitor, stainless hardware. The only difference is the different toroid, the way its wound, and the plastic case. So we’re really doing an experiment to see what the effect of using a different toroid is in terms of what my NanoVNA thinks.
Then I went and attached my NanoVNA and did a 40 to 20 meter sweep for a baseline.
Then I went outside and swapped the 49:1’s using the same wire and coax and did a sweep of the same 40 and 20 meters. Pretty much identical. I might have tripped over the too-long 50 foot coax and cause another loop to form or open 😉
Just for grins I did a 6-50Mhz sweep, too, just to make sure it looked sane.
So the 2 seem identical in the eyes of my NanoVNA. I’ll probably do some WSPR, FT8,JS8Call, and SSB tests tomorrow to see if there’s a measurable difference or not using my 100W max Icom 7100 and 200W max boat anchor Kenwood TS-180s. Not that I intend to use full power – to the contrary – but I like my transformers to be able to handle it if needed.
I do need to modify the wire length so that it resonates a little lower on 40 and 20 meters. At least I don’t need to lug an ATU downstairs when I want to ham it up from the kitchen table or backyard.
73
ÆØRS
