I started this afternoon testing various end fed wire antennas when I hit 29ft with a 9:1 being to be the perfect combo with 50ft of coax and a ugly balun at the beginning. Then I got to thinking of the antenna Gary gave me and the extra bits too. So I stacked a 29ft aluminium mast and stuck the 9:1 on it. It worked pretty good albeit very directional. So I'll test again with my fans of 1m radials. Nice to put something together that actually works for a change and zero maths applied to it.
So the chain goes like this right now
Radio -> coax -> ugly balun -> 50ft coax -> 9:1 Unun -> 29.5ft aluminium straight up.
Note: I needed that ugly balun there so the coax shielding reflection would work as a counterpoise for the antenna. That's why it was very directional.
This is the first test in the line of probably many. I have spent quite a bit of money playing around with failed antennas. So this time around I'm trying to almost solely use junk to prove it works first. I got a few variable caps from Milton the other day, unfortunately they just weren't big enough for this project. However they do work for fine tuning. The cheapest cap I could find online for power was 55$. Nope, not spending 55$ to find out it really doesn't work. So I came up with this idea for a capacitor. Not sure what it's capacitance is as the battery in my meter went dead this morning while testing it. It currently works only on 20m even though it's design is for 40m. Later today I'll setup in the yard to test it on battery power. Maybe try the LiFePO4 batteries too.
I did take it to the yard and got one QSO with AF6O in California. That was the point I realized I wasn't feeling very good and packed it all up and went back inside.
Got bored this morning so I built me a multi-balun out of the loose junk I had.
This is the next antenna I'm building. The only piece I need is the variable cap. I plan on making the frame from PVC that fits in my tripod and making it remote tune-able
I'm grabbing this now as we all know how the life expectancy of a tripod website. Remember geocities,
----------------------------->8 Clipped from website 8<-----------------------------
UPDATE: Math from 66Pacific which I will try first before committing to the original design I found. I'll make a second loop to get me 80m and if it fails then build another 40m and sell it as such.
Antenna efficiency: 36% (-4.4 dB below 100%)
Antenna bandwidth: 15.4 kHz
Tuning Capacitance: 122 pF
Capacitor voltage: 2,912 volts RMS
Resonant circulating current: 15.6 A
Radiation resistance: 0.074 ohms
Loss Resistance: 0.132 ohms
Inductance: 4.25 microhenrys
Inductive Reactance: 187 ohms
Quality Factor (Q): 454
Distributed capacity: 16 pF
Antenna "circumference": 20 feet
|Side length: 2.50 feet|
Antenna diameter: 6.0 feet
Well I revisited the inverted v dipole I had previously made and with the help of a couple of calculators came up with an off center feed dipole. But this time instead of cutting my wire to the length required I started from the terminals of the 4:1 jetstream balun to the receiving part of the dogbone. One element 23' 2" 3/8 and the other element 46' 3" 5/8 and holy smokes what a difference. 40m, 20m and 10m I get 1:1 SWRs. Which really doesn't mean much as my can-o-dummy gets 1:1. I haven't had a chance to test it's range. Nor have I plotted it in MMANA. This was just an impulse brain fart. But I calculated 1/3 wave for 7.074 and doubled that for the other side. Before that I was trying to find a happy middle between digital and phone, but that's a difference of 3 feet from end to end. And neither side feeling the joy of resonance. So since I do more digital I sided with the lengths for digital modes. I may fire up the smelter furnace and do some lost PLA casting to make an octopus antenna using ham stix this summer for my next project.