I went to the qrp guys web site to see if the triband end fed had been moved from in development to for sale yet, and discovered that they have added another in development product…
They are listing a center loaded vertical for 80m using a coil form instead of toroids like the triband model.
It still fits on a 17’ fishing pole.
While likely rather inefficient it’s a novel idea.
I’m guessing a tap could be added to add 60m on the coil form as well…
I emailed the “guys” and told them I thought they were missing the opportunity to include 60m in the same antenna. I did the math and based on rough calculations I determined approx where they should tap the coil a second time to be centered on channel 3.
Ken tested it out and found it matched well on 60m, although not quite where I thought it would be (in my defense I didn’t have the coil form dimensions or a mock up in-front of me).
If you look online the antenna is now advertised as 80/60m and the instructions include the 60m tap location. I think its pretty neat that the company puts out in development products so we get to see what’s cooking before it comes out. In this case a suggestion made it into the final product before it ever got sold
I will likely have different tap locations on my example as I use a 20’ pole, not a 17’ pole that the antenna is designed for. Since I have the real estate I will be adding 1.5 feet to either side of the coil. That 120% of the original design’s vertical radiator, so slightly better efficiency on both bands.
I’m guessing the fact that they have a 20/30/40m vertical designed to fit in the same space is the reason why I didn’t suggest adding taps for those bands. Also, to get the coil to fit in the PCB at the bottom, you have to be careful with how many taps you add and where you put them.
With that said, if I modify mine to be closer to 17’ overall length you should be able to bypass the coil completely for a 1/4 wave on 20 meters. Adding a tap for 40 may be worthwhile, depending on how you feel about the efficiency of the toroidal base loading of the other design. A center loaded air coil should be more efficient than a base loaded toroid, assuming the same amount of vertical radiator.
yes, center loading is a superior design. It makes all the sense in the world to me to make a 20-60M (don’t care much for 80M daytime use personally) single antenna solution for SOTA
How is the coil held in place over the pole?
Can you please post a link to the eBay pole that this works with? Are they the “7.2M” fiberglass poles from China?
Congrats on a really great product idea and great price!
Just to clarify, I only suggested the 60m tap. They are the ones who designed everything else.
The coil is designed to slide over the fishing pole in question to prevent movement in the wind, and there is a tiny PCB used as an end insulator that also fits over the pole. Finally, you can rubber band or tie off the base to the pole for a third point of contact. Any day that isn’t “windy” this isn’t really needed. Even just using the end insulator is likely sufficient.
I’m having trouble finding the 17’ fishing pole they reference. 20’ Crappie fishing poles (the B&M brand is what I use) are easy to find for around 20 dollars, sometimes cheaper.
try searching on “7.2M fiberglass fishing pole” - these are really much shorter than 7.2M (5.4M actually=17.7ft), go for about $10 and are probably the correct ones. They’re 26in long and weigh .5lb so they are very pack friendly as well.
I got it after reading (here) several people saying they were using them w/o problem. I tested it briefly as a sloper and vertical and it seems to work as my fiberglass mast does. YMMV I suppose.
Yeah, if I had to guess, I’d say the only carbon fiber bit is the last section which is the one that’s too thin to support anything (Fred KT5X suggests gluing it in the next section down to add stiffness).
I keep reading people saying this. I’ve just got the verniers onto my 5m travel pole, the top section is 2mm OD at the top before the metal eye and 3.8mm at the bottom. As this telescopes down to about 55cms (23in) the top secition is about 30cm (12in) long. I happily support verticals with a loading coil 1/3rd up or an inv-v dipole for 60/40/30m with 10m of RG-174 feeder. I don’t have any worries about it not supporting thin wire.
What are you guys hoisting up your poles? Elephants? Rhinos? Hippos? I think we should be told.
I’m pretty sure you have to put a goat on the pole or you won’t get any spots, right? Maybe I’m doing it wrong.
In any case, recommendations for sources of poles that collapse smaller are welcome. I like the sotabeams compact 10m mast but I’d be happy to find something a little shorter with even smaller segments.
Seriously though, this might be a matter of EF sloper vs dipole. 60’ of wire pulling in one direction with no counterbalance, even if light gauge wire, is a bunch of weight. The tip section of the one I just got is scarcely matchstick thick.
