CatSnoutSoup
NES Member
My current antenna for 40m/80m is an Alpha Delta DX-DD dipole it is 82 ft. long and set up suspended from a rope that is sloping down from my 54 ft. tower, Tashijian (Tri-Ex) LM-354. It slopes down to the handrail of the second floor deck on my house 156 ft. away where it is tied off at about 19 ft. above the ground. That is the suspension rope, the antenna itself starts about 5 ft out from the tower at 53 ft. and slopes down till it ends at about 35 ft. above the ground. The feedline is coax RG-8X dropping from the center point of the antenna and then Davis BuryFlex from there to the shack. Due to the length of the run it is not a super efficient feedline setup, unlike the LDF4-50A, HELIAX that runs from my tower to the shack. Never did get around to getting that Array Solutions RatPak remote switch I wanted for sharing that hardline run.
That old antenna has been up since 2009 and I feel it is time for a change. So I am returning to the same antenna I used for 80m/40m before it got shredded in a direct lightning strike some years ago. That antenna is the 140 ft. Cobra UltraLite Senior from Granite State Antennas (K1JEK).
The Cobra is fed via ladder line (450 ohm window line actually) and it matched well through the 4:1 balun in my external tuner when I owned the antenna in the past.
But I had the antenna located differently back then and the antenna's preassembled 81 ft. of ladder line is not going to be long enough to make it to the shack this time. So to add on to the stock ladder line I have some 450 ohm, 16AWG, 19 strand, CCS ladder line from Davis RF.
Now I could just use some crimp butt splices to connect the stock ladder line with my extension. But I also thought maybe I would get creative and turn the splice into a optional disconnect. So I went looking for a knife switch to perform the task and knew I found it when the first Amazon review I read for this change-over switch was from a ham doing almost the same thing with it.
The contacts are quite solid and it should handle a KW of RF power passing across. The plan as seen in the text I added to the photo I took is to the have the stock ladder line from the antenna enter the center contacts, then if the knife is closed to the left makes the connection to my extension line to the shack. If however the knife is closed to the right I will send it to a ground rod with some 4 or 6 AWG copper I have.
I will smear the contacts with some dielectric grease (Superlube same thing I use on guns) then install the switch in a water resistant enclosure (plastic drinks cooler weighted down with gravel) so when not operating I can leave the antenna disconnecting to ground before the line even gets to my surge suppressor at the shack entrance.
The only question is what kind of impedance I am going to end up with at the shack. Ideally you want as close to 200 ohms as you can get presented to the tuner's 4:1 current balun.
I guess we shall see, and if it does not work out I can always fall back to those $0.02 crimp butt splices.
BTW if this post hasn't revealed what a geek I am then how about this... A screen shot of me rough modeling the tower, house, and old antenna in AutoCAD before drawing in the new antenna to figure out rope and feedline lengths.
In my defense it is a chilly weekend, I am inside and this is fun (at least to me). But I did talk my wife into coming out and holding the end of a 300 ft. engineers tape so I could take measurements.
P.S.> If you are not using Davis RF for your cable and wire needs then you are missing out on fair prices and the opportunity to support a local (NH) company.
That old antenna has been up since 2009 and I feel it is time for a change. So I am returning to the same antenna I used for 80m/40m before it got shredded in a direct lightning strike some years ago. That antenna is the 140 ft. Cobra UltraLite Senior from Granite State Antennas (K1JEK).
The Cobra is fed via ladder line (450 ohm window line actually) and it matched well through the 4:1 balun in my external tuner when I owned the antenna in the past.
But I had the antenna located differently back then and the antenna's preassembled 81 ft. of ladder line is not going to be long enough to make it to the shack this time. So to add on to the stock ladder line I have some 450 ohm, 16AWG, 19 strand, CCS ladder line from Davis RF.
Now I could just use some crimp butt splices to connect the stock ladder line with my extension. But I also thought maybe I would get creative and turn the splice into a optional disconnect. So I went looking for a knife switch to perform the task and knew I found it when the first Amazon review I read for this change-over switch was from a ham doing almost the same thing with it.
The contacts are quite solid and it should handle a KW of RF power passing across. The plan as seen in the text I added to the photo I took is to the have the stock ladder line from the antenna enter the center contacts, then if the knife is closed to the left makes the connection to my extension line to the shack. If however the knife is closed to the right I will send it to a ground rod with some 4 or 6 AWG copper I have.
I will smear the contacts with some dielectric grease (Superlube same thing I use on guns) then install the switch in a water resistant enclosure (plastic drinks cooler weighted down with gravel) so when not operating I can leave the antenna disconnecting to ground before the line even gets to my surge suppressor at the shack entrance.
The only question is what kind of impedance I am going to end up with at the shack. Ideally you want as close to 200 ohms as you can get presented to the tuner's 4:1 current balun.
I guess we shall see, and if it does not work out I can always fall back to those $0.02 crimp butt splices.
BTW if this post hasn't revealed what a geek I am then how about this... A screen shot of me rough modeling the tower, house, and old antenna in AutoCAD before drawing in the new antenna to figure out rope and feedline lengths.
In my defense it is a chilly weekend, I am inside and this is fun (at least to me). But I did talk my wife into coming out and holding the end of a 300 ft. engineers tape so I could take measurements.
P.S.> If you are not using Davis RF for your cable and wire needs then you are missing out on fair prices and the opportunity to support a local (NH) company.
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