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KX2/3 w/tuner owners: what antenna do you use?


#1

I’m adjusting to QRP operation and reviewing my antenna options with an eye to getting as many of my 12 watts airborne as possible. I am interested in hearing what other owners of KX2/3 w/internal tuners use for activations.

For what it’s worth: I’d be replacing a Buddistick setup and an EARC style 9:1 w 30ft radiator. The Buddistick has moments of brilliance, but is much more suited to setting up for 24hrs. Switching bands can take a long time, and when it’s 0f and you want to get off the hill asap it can seem like eons. The EF has served me well in QRO operation, but I suspect it’s not as efficient as I would want given some reading I’ve been doing.

Thanks for the help.

73,
Joe / N0MAP


#2

I think the EARC antenna is okay if you keep the coax quite short. But you can’t run 30ft of coax to it.

You can run a random wire/counterpoise right into the rig and eliminate feedline loss. Or you can run a balanced feedline from random center-fed doublet (e.g., 44ft doublet)

73, Barry N1EU


#3

Hi Joe

I use a KX-2 + EARC 9:1 and a long wire (i use the longest wire possible in each summit). No counterpoise. The feeder is a RG-174 (6 m +/-). The pole is a 5m high glass fiber (fishing rod).
I run several tests with and without counterpoise without noticing any difference. I believe the 6m (~30 ft) of RG-174 are acting as a counterpoise.

FB antenna with great results. Several QSOs, while activating summits, with other continents, including VK, ZL, W, etc.

Most operation 60-17m, mainly 20-30-40m.

The EARC was homemade.

73 de Pedro, CT1DBS/CU3HF


#4

I should have noted that I use a 12’ run of coax. I could probably get by with 6’ if needed.

I also should have noted that 95% of my operation is on 20m and 40m. I am starting to use 30m as I do more CW on activations.


#5

Thanks Pedro. Yes, my EARC is also homemade. Ferrite core toroid.

So re: the longest wire possible. Do you just bring a spool of wire and roll out whatever fits on the given summit? I suppose that would mean having a spooling mech that is light enough to go up on the fishing rod?


#6

That’s the way to go, especially if it’s RG58 and not RG174.

53ft of wire is a recommended length for 40, 30, and 20M.

73, Barry N1EU


#7

Other way around with the coax, right? Isn’t RG174 more lossy? In any case, I do have a 6’ RG174.

GTK on the length. I’ll give that a try. I’ve been using 30’ which is probably too short for 40m. It tunes up, but I consistently get much poorer signal reports on 40 compared to 20. Given my qth and time I’m usually activating (~1500z), 40m is my bread and butter. 20m tends to overshoot the east coast and the west coast isn’t in the shack yet.


#8

I made one of these, but out of speaker wire. Except for the end insulators breaking off every 100 or so activations, it has served me well.


#9

the way to go is RG58 (or RG8X) is what I was trying to say

sorry, despite Pedro’s good experience, you can do a lot better than running 30ft of RG174 between rig and transformer. There is high SWR on that feedline on many bands and the losses will be high.


#10

Speaker wire is a poor (lossy) xmsn line above 10MHz due to the dielectric properties of the insulation. It will work, but you can do much better using window/ladder line, teflon insulated twisted pair (from high speed CAT5e/6 cable), etc


#11

Doesn’t surprise me, but the antenna still works fine. I have plans to put together a trapped EFHW for 40/30/20 so I can stop carrying a separate tuner.


#12

I have been using a 20/40 trapped dipole from http://www.qrpkits.com/dualbanddipole.html feed point about 18’. I just made and yet to try a 25’ wire with a 25’ counterpoise as per the KX2 manual. I plan to try on Friday. I’ve tried a random wire end feed but for the life of me I could get good results with it with shorter lengths of wire…

Malen
VE6VID


#13

A unun is unnecessary with the KX2 or KX3 internal tuners. I routinely use a 58-foot radiator and a 13-foot counterpoise connected to the radio with a BNC-to-dual-post adapter without a coaxial cable. Make sure the radiator does not touch the ground, including boulders. If you can lob the radiator really high over a tree branch, this antenna system will cover 80 m through 10 m okay. If you cannot get the radiator very high, then the antenna still works fine from 40 m through 10 m. To get coverage on 80 m and 60 m with the radiator relatively low above the ground, then an 84-foot radiator and a 17-foot counterpoise works best for all HF bands. You’ll have lower losses if the leader and not the radiator rests on the tree branch. For less wear and tear on the tree, remove the rock or the fishing weight which you tied to the brightly-colored lobbing leader before retrieving the antenna. I tie the leader to a fist-sized rock using a scaffold knot (Google it!). If there is snow on the ground or if I’m operating in a mature forest with heavy organic material covering rocks, then a brightly-colored fishing weight is worth the extra pack load. I use a figure-eight loop which I thread through the heavy wire loop in the fishing weight and lock with a girth hitch. Since I value my brain, I wear a helmet for the David-sling-style lobbing operation. I chose an orange climbing helmet so I can wear it during the hunting season. In a treeless area you need something to elevate the radiator. Check sporting goods stores for a nesting pole. I bought a Chinese-made one from the internet, but I can’t find a URL for it. The labels include DIAO BUDUAN and 720 and TXDU. Perhaps somebody else can locate it and post the URL. 73, Bruce Prior N7RR


#14

Joe,

The 9:1 un-un and wire is a great antenna with KX2/3. The quick setup will get you on the air fast and be making contacts while a (possibly) more efficient (i.e. dipole) install would be wrapped around every sticker bush in the county! Plus the band switches are instantaneous. Bottom line, more contacts in a short amount of time with that antenna vs dipole/buddipole/etc (IMHO).

One comment would be to lengthen out your antenna to 35.5 feet. See the numerous “best long wire length” charts on the web. Recommended lengths are: 35.5 41 58 71 84 107 119 148 203 347 407 423 (all feet). Going with 35.5 vs 30 does mean it is slightly longer than a 10M SOTAbeams pole, but I just slope the bottom end out. Note I tape the wire to the top and then about 7 and 14 ft. down from the top.

As far as coax goes, it is recommended to have a 25 ft of coax as the coax acts as the counterpose (info here: https://kx3helper.com/endfed-40-6m-antenna/). I started with 25ft of RG-58, but now use RG-174 for my ultralight setup. Can’t really tell the difference (58 vs 174) and solid into the skimmers as always. http://www.cablesondemand.com/pcategory/20/category/CO50OHM/URvars/Catalog/Library/InfoManage/50_OHM_COAXIAL_CABLES.htm has been a good source of both.

In the end, the KX2/3 will tune up without an antenna connected (the tuner is amazing). Like N7RR said (also see WG0AT setup) you can direct connect wire to the KX2/3 and it works great. I think you will like the endfed for ease of setup, band changes and it really does get out great from a summit. Even works with it laying on the ground with the mast falls over :wink:

73, Jim/K7MK


#15

Exactly the set up I use Bruce, works really well

Terry G4POP


#16

What’s an “end insulator”? :wink:
I use short loops of woven Dacron fishing line, preferably in fluorescent orange so they are harder to misplace. And/or plastic Nite Ize S-Biners. Occasionally the larger #275 paracord. Never 550 paracord for portable work.
I often clip things together (guy lines, support lines, stuff to squid poles like transformers, etc) with stainless steel Nite Ize S-Biners, size #1, sometimes size 0.
I find that size #1 are easier and quicker to operate while still being light and low bulk. Fast setup, even faster bugout. I always pack a few spares.

In the US, Home Depot carries an assortment locally or mail order them from your favorite online vendor.

I also use the Nite Ize plastic Mini CamJams with #275 paracord (fluorescent orange of course) for tensioning ropes and attaching squid poles to various objects.

No association to Nite Ize, just a very happy repeat customer.

BTW Homebrew: 67 feet 24 gauge Tefzel EFHW, 64:1 FT140-43 transformer, 30ish feet LMR195, coax/counterpoise, squid poles, etc.

I sometimes get reports of RF in my audio (band and coax length/position specific). Moving the coax around often solves the issue. 3 turns of coax through a large type 31 clamp-on ferrite solves the problem but adds weight.

73,
Bruce W2SE


#17

In a recent SOTA antenna test, all the wire antennas were pretty much the same except for the EARCH antenna, which was much worse.

wunder


#18

This is one of the bits of info which gave me pause. That said, even the tester notes that the EARC setup was sub optimal. He was running 10m of RG174 to it. I don’t know where that leaves the comparison.


#19

Hmm, 58’ with 13’ counterpoise. Off I go to cut more wire to give it a try on Friday. Use a golf ball with an eye bolt in it, bright green as a throw weight.


#20

Pretty hard to lose that many dB in 10m of coax, even with a bad match.

I’m guessing that the EARCH transformer is lossy. That would make it broadband, but at a cost.

wunder