Rebuilding the WARC Trap Inverted-V

Inverted V just below beam.

Fifteen years ago, I put up a trap Inverted-V antenna for 30/17m roughly the 12.5m level of the tower -- right above the rotator where the tower necks down to a single tube. A couple of years latter I added 12m traps to have  coverage of all the WARC bands. 

It was my first experiences building trap antennas. Naturally, I did everything wrong.

I originally created the traps using series-wound coax cable traps. They seemed easy enough to make, and pretty weather-proof. I also made the traps resonant in the band.

This article by Tom Rauch, W8JI showed me the error of my ways. 

Coaxial cable traps actually have a rather low Q. And any trap that is resonant in the band in use is going to induce more loss. Tom's advice is to make traps with discrete components, and put the trap resonance outside the band. 

Old coaxial Traps. The 17m traps are only 5
years old, but they are badly weathered.

From the modeling work I've done, a trap antenna works with the trap resonance just about anywhere between the two bands. I tend to push the resonant frequency close to, but just below the frequency - usually by 3-5%. They key is to make pairs of traps identical, so their resonant frequencies are  the same. 

I used a rather small value for the capacitor in the trap. The actual value isn't critical, anything will work. A smaller capacitor tends to couple less energy out past the trap above resonance. You'll always get some current in the entire antenna (unless you operate at trap resonance - but then you'll get the most trap loss, too). 

A smaller capacitor means a larger coil, and on the lower frequencies, this inductive loading shortens the antenna a bit. Pick a coil diameter so that the length / diameter ratio is somewhere between 1/2 and 1, as this generally results in higher Q. 

New traps, 17m on left, 12m on right.

The replacement traps are constructed on 1 1/2" schedule 20 PVC, which is roughly 1 5/8" OD as follows:

• 12m - 6 turns 14 gauge THHN and a 22 pF 6 kV capacitor, resonating about 24.4 MHz
• 17m - 9 turns 14 gauge THHN and a 27 pF 6 kV capacitor, resonating about 17 MHz

I used the existing length of 14 gauge THHN wire for the 12m segment, which, unfortunately, I did not measure. I'd start with 112" each side. the 17m segment is 18 1/2" of 12 gauge THHN each side, and the 30m segment is 93" 12 gauge THHN each side. The 30m segment is doubled back about 8" each side, twisted to connect to the end insulators. The total length of the antenna is about 37 feet.

I trimmed the Inverted-V by running it up the tower to about the 35 foot level using a rope and pulley. I learned this technique from the last time I repaired this antenna. This round, trimming only took four attempts. 

The antenna SWR curves fit perfectly on 30m and 12m, where the SWR is less than 1.5 and 1.2 across the entire band, respectively. 17m the SWR is closer to 2:1, with the lowest SWR at 18.010 at 1.58:1. In retrospect, perhaps I should have trimmed another 1/2" off the 17m segment. 

The apex of the Inverted-V is about 12.5 m high on the tower, about 8 feet below the A3S/A743. I used my RigExpert AA-55 to measure the SWR curves of the A3S/A743 before and after installing the WARC Inverted-V. There was no appreciable change in these curves on any band, which indicates there is little interaction between these antennas. 

4U1UN (and 4U75UN)

A little more than a year ago, I was looking at the Most Wanted list in ClubLog. I noticed that the United Nations HQ entity was number 30 on the list. In all my years of ham radio, I had never heard them on the air, much less worked them. I wondered if I'd ever have the opportunity to work them at all.

Well, the 4U1UN club has been busy, and late fall 2019, they finished their installation which allows them to remotely operate a transceiver near the top of the UN towers from a room on the ground floor of the building. Since that time, they have been sporadically active. 

I don't know what the rules are for operating 4U1UN, but the station has been active at least some time every month during the past year. They have gone from an entity you'd wonder if you'd ever work, to one that can easily be worked by anyone with a bit of determination.

Over the past year, I've kept a running DX Watch query going to see when they were on the air, and worked them any time I could hear them. They've been easy to work even with compromise antennas.

They confused me in September, as I thought they had gone silent. No, they just switched callsigns. They are celebrating 75 years of the UN with the call 4U75UN. There's a special certificate for working them. They should continue with that call until December 31st.

They'd be pretty easy from the USA on 160m, but I don't believe anyone has ever operated on that band. I doubt they have an antenna, and I head the noise level in NYC is extraordinarily high.

They QSL promptly through LoTW (be patient, it may take a week or two to be uploaded). I've gone from wondering if I'd ever work them to having them confirmed on nine bands (80m-6m) and three modes: CW, Phone and Digital. 

Keep an eye peeled on the spotting networks, and perhaps you can work a new one.

VP6D on 30m CW

Odd things happen. During a long DXpedition, like the current VP6D expedition to Ducie Island, they are bound to happen. They happened during the K1N Navassa Island expedition, for example.

Last night I'm trying very hard to put VP6D in as many DXCC slots as I can. I hadn't worked them on 30m, and they were running RTTY. 30m is often tough, since everyone runs 200 watts, tops, and my 100 watt signal doesn't really stand out. RTTY makes it even harder. I called for a half an hour with no luck. And then VP6D disappears.

I continue calling for a little bit. It's a sort of anxious hope that sometimes works. Maybe they had a generator die, and the first thing the operator will hear when the generator comes back to life will be my callsign. Right? Well, it could happen.

After a couple of minutes I stop calling. I'm sitting there with the headphones on. The left ear is listening to 10142 kHz at about 450 Hz wide, the right is listening up around 10144.5 kHz, about 2 kHz wide. And, I'm hearing nothing. Nothing at all.

About three minutes after I stopped calling, I heard a signal. It sounds like a CQ. A CW CQ. It's off frequency, so I can't really tell. I'm not set up for CW. I'm in DATA mode, with settings all flipped around with wide filters. But - there it is again - in my right ear, it sounds like VP6D calling CQ, in CW.

Switch things around to CW, with a narrow filter, and then tune for the right frequency. I'm sure I'm going to miss it, but no, I find him. There he is CQ VP6D UP2. Plain as day on 10144 kHz. That's not where you'd expect him to be at all. No, the published CW frequency is 10105 kHz. This frequency is out of position for CW, but there he is, calling CQ VP6D UP2. And no one is answering. No one.

This is my chance. I go into split, up 2, and give him a call. But, again, CQ VP6D UP2. A couple of times. No answer. So, I figure, hey, maybe he's actually listening up 1 and doesn't realize his memory keyer doesn't match. I dial in up 1, and call. No dice. After a few calls, I wonder where he's listening really. Maybe he's listening up 2 from 10105 kHz. I give him a call on 10107 kHz. Nothing. Perhaps he's listening on his own frequency?

At this point, he's been calling CQ on 10144 kHz for two solid minutes and no one has answered him. I figure it's worth a try without being a DX lid. I turn off split and dump in my call: AA4LR. AA4LR 5NN comes the response. R 5NN TU, I reply.

And bam, quick as that, he's in the log.

He goes back to calling CQ VP6D UP2. I listen for a couple more minutes, but no one is calling him. I post a spot on dxwatch.com and listen for a couple more minutes. Still no one. I begin to wonder if he's just clueless to where he is in the band, and that no one is looking for him there. So, I dare to send again on his frequency: FREQ? He responds to my question by sending 10144 twice. So, yeah, he knows where he is. I post another spot, hoping some other DXer will find him, too.

After about 10 minutes of this, he goes silent. A minute after, I find him down on 10105 kHz, once again calling CQ VP6D UP 2. And, people are calling him, and he's answering. Good, that's what's supposed to happen.

Looks like I'll may be the only one who worked VP6D on 10144 kHz CW. Cool.

5BDXCC? - Well, Not Really.

Back in December, I made my annual submission to the DXCC desk. In addition to adding a few endorsement entities to my DXCC Mixed, CW, Phone, Digital, 40m, 20m, 15m and 10m, I also submitted enough credits for DXCC 30m as well.

Let's see, thats 40m, 30m, 20m, 15m, and 10m. That's five bands! 5BDXCC, right?

No, not really. 5BDXCC requires DXCC on 80m, which I haven't accomplished yet. Getting there.

DXCC - Meeting the Challenge

Since I started uploading my logs to the ARRL Logbook of the World in November 2003, I've been working toward the DXCC Challenge. I've been carefully trying to work DX stations on multiple bands, hoping to get my current entity-band totals past the Challenge threshold of 1000.

Well, sometime this weekend, I received enough confirmations to get me past the 1000 mark. At the moment, I have 1003 entity-bands confirmed.

I guess I'll be submitting an application for the DXCC Challenge this year! That along with 30m DXCC.

UPDATE: I also notice that I have exactly 239 current entities confirmed for Mixed DXCC. This means I'm exactly 100 entities away from working all 339 current entities, or 91 away from the DXCC Honor Roll.

The Venerable TS-430S

The Venerable TS-430S with AT-250 antenna tuner.

I realized earlier this week that my backup rig, the Kenwood TS-430S, turns 30 years old this month. Yup, I bought that rig back in September of 1985. For the next 16+ years, it would be my only HF rig.   I held on to that rig so long, by 1995, I was already calling it "venerable."

How I got to that point is an interesting story. My original Novice setup was an SB-301/SB-401 combo. In my second or third year of college, I sold my SB-401 to my brother Ben (now NJ8J). I still had the SB-301, and eventually I set it up in one of my college apartments. But I lacked a transmitter.

One summer, I attempted to rebuild my Novice transmitter using a 6GK6 and 6146 design published in the ARRL handbook. I added a lot of extras, like a built-in VFO and a KOX (key-operated-switch), with automatic T/R switching. (the VFO and KOX board were salvaged from a home-brew 40m QRP rig project that I assembled, but never could get to work) I never could get any output from that 6146 rig, and it chirped pretty badly.

Shortly after I finished college and moved into an apartment, I borrowed a friends FT-101E. The rig worked great. Because of my crummy antenna situation, I had a lot of trouble making contacts. Eventually my friend asked for his FT-101E back.

Since he bought the SB-401, my brother wasn't using a Heathkit DX-60B he had, so I borrowed it. I pulled the VFO out of the Novice transmitter, mounted it in a box with the KOX circuit board, a power supply and connectors for the DX-60B. This actually worked! I made a handful of contacts, but again the antenna situation really limited me.

In the summer of 1985, I moved to a new apartment much closer to work. It was two stories tall, and there were a number of trees about 30 feet away from the back. I took a couple of 100 foot spools of #26 wire wrap wire and strung them into the trees from my second-floor shack window, fed from the back of a crappy MFJ tuner with a balun. This formed a crude doublet.

For an operating table, I bought a door, placed it on two short two-drawer filing cabinets, and finished it with stain and polyurethane. I did a good job, because this door is still my operating table to this day in Gwinnett county.

I still needed a rig. I decided I didn't want to fool with tube-type radios any more. (That urge would return later) I wanted something that was all solid-state, had a direct-reading frequency display, supported the new WARC bands, and didn't cost terribly much.

At that time, the top contenders were the Kenwood TS-430S and the Yaesu FT-757GX. Both had a reasonable feature set, and were similarly priced around $600. I don't know what tipped me toward the Kenwood. In retrospect, based on what I know today, the FT-757GX had more features -- it does full QSK and has a built-in keyer, as well as supporting computer control via the CAT system. Computer control would be something I would pine for a few years later when I got into contesting.

Back in 1985, I wanted to get the best deal on my TS-430S, and I must have called a dozen different dealers for a price quote. The deal I found was a TS-430S for about $630, including the optional FM board. I placed the order with my credit card -- and this was perhaps the first time I would go into debt for my hobby.

I didn't do a lot of operating from that apartment, but I did enjoy the TS-430S. The crude doublet actually worked pretty well. I spent a fair amount of time on 30m, which was a relatively new back then, but I also hung out around the Novice bands on 80, 40 and 15m.

I moved to a house in Stone Mountain, GA, and the TS-430S was my main rig. My antennas progressed from a 300 long wire to a loop skywire, to a 125 foot doublet, eventually complemented by a Butternut HF4B beam on a roof tower that eventually gave way to a Cushcraft A3S. I started contesting in 1986 with CW Sweepstakes. The TS-430S paved the way for a whole lot of radio experience for me.

As a rig, the TS-430S is not a bad performer. There are two key deficiencies that were fixed by it's successor, the TS-440S: a) computer control, b) 100% duty cycle. The TS-440S adds a host of other features (100 memories, internal antenna tuner, selectable filter bandwidths, FSK, selectable AGC) Ironically, the TS-440S would be introduced at Dayton in 1986, just a few months after I bought the TS-430S.

CW performance is reasonable, depending on your expectations. There is no QSK, but the VOX operation from the key is quick and reliable. You can at least listen between words. AGC action is fast. The 500 Hz CW filter is a must-have.

SSB works well. VOX is fully adjustable, and the speech processor produces reasonable results on air. Choosing LSB or USB, though selects the slow AGC, which is annoyingly sluggish.

FM is interesting. I played around with 10m FM in the late 80s. There used to be a few guys in the Atlanta area that would hang out there back then. I think it may have faded, along with a lot of 2m FM.

Receiver performance is pretty good considering the up-conversion design and the vintage. There's certainly some front-end IMD, which you hear as a "sparkle" sound, especially on 10m when it is open during a contest. Usually hitting the attenuator knocks that out. The notch filter is pretty good, provided you are only dealing with one carrier. Of course, you have to adjust it manually. Noise blanker is one of the better ones.

Some contesters would be displeased with the manually-centered RIT. Never bothered me. IF Shift can sometimes help fight QRM -- but not in really crowded conditions.

This rig has some features I have rarely used. General Coverage Receive is one of them. Program scan has got to be the most useless of all -- since you have to manually hold the scan if you hear a signal.

I have made a handful of mods to my TS-430S. I did the 10 Hz frequency readout right away. (Why they didn't ship it from the factory this way, I'll never understand) Back when I used transverters for 2m, I enabled all-frequency transmit. Oh, and I did a simple mod that allows the YK-88C 500 Hz CW filter to be used for SSB narrow. This is useless for Phone, but makes easy work for RTTY.

Running RTTY is a mixed blessing. With the 500 Hz filter and the IF Shift adjusted, it does respectably on receive. The slow AGC is a little bit of a problem. Transmitting, though, should be limited to about 50-75 watts. Be sure to turn off the speech processor.

This rig has been with me at five different QTHs, as well as a host of Field Day operations. Although I long ago bought an MB-430 mobile mount bracket, I have never mounted it in a mobile.

Considering all the rapid changes in electronic and radio equipment in the late 70s to mid-80s, what with the transition from tubes to transistors to integrated circuits, plus the addition of new amateur bands -- it is amazing this rig still holds its own. I certainly didn't expect to be using it 30 years later.

K1N - Fabulous DXpedition

My Results from K1N

Well, it's over now. The much-anticipated K1N DXpedition to Navassa Island is now over. Lucky for me, I made it into the log multiple times, which makes me quite pleased.

Granted, it was a pretty easy shot from here in northwest Georgia to Navassa Is compared to other parts of the world. They were quite strong on just about every band, with the exception of 10 and 12m. I never heard a peep from them on 6m.

The pileups in the low bands were completely crazy in the evenings. All of my contacts 30m and below were made in either the 0900z or 1000z hour -- 4 or 5 AM local. That's one of the secrets of working DX -- be on the band when others are not! The one exception was 60m, and, honestly, the channel was so crazy I'm not entirely sure how I made it into the log.

All of these contacts were made with 100 watts and wire antennas, either the Inverted-L or the 80/40m dipole. Working DX does not require huge amplifiers and large antennas.

The team on Navassa Island did a fantastic job handing out contacts despite unruly pileups, deliberate QRM and the usual craziness. I witnessed on CW pileups that extended over 30 kHz with people continuously calling. Finding the listening frequency in the second receiver was an incredibly difficult task, and quite often I was just guessing -- but a few times I got lucky.

As I told my friend Mike, W1YM, now that I have Navassa Is on nine bands, I'm planning to volunteer to operate the next time team heads to the island. Perhaps in 10 years....

Forth Quarter in Centennial QSO Party

No, I don't use paper any more....

We're now well past half-time. It's the beginning of the forth quarter.

Honestly, I'm amazed at the Centennial QSO Party. I have really enjoyed the W1AW-portable operations. I checked my records and I have made nearly 900 QSOs with W1AW-portable stations this year. 820 of those from Floyd County.

I'm kicking myself for not starting this right off the bat January 1, and pursuing these portable operations on every band/mode combination. Nope, I ignored these operations until February, and at first I was only trying to fill in bands - like 30m, 17m, and 12m - that I didn't have confirmed already.

Now, I'm having too much fun. I'm ducking into the shack each day to try and work a few band/modes that I can. It's been fantastic practice trying to break into the pileups.

I'm really, really impressed at how much I've been able to work with just 100 watts and wire antennas.

And the WARC-band WAS? I'm advancing. 30m - 45 confirmed, 17m - 40 confirmed, 12m - 29 confirmed. And there's still W1AW-portable logs that still haven't been uploaded.

If you haven't tried working these, there's still three months of fun left. Join in!

Half-time at the ARRL Centennial QSO Party

This logbook was last used in 2006.

OK, we are now half-way through the year, and that means we are half-way through the ARRL Centennial QSO Party, with portable operations of W1AW visiting all fifty states!

As I wrote earlier, the Centennial QSO Part is a great opportunity to get nine-band WAS confirmed, since all of the W1AW-portable operations are being loaded up to the Logbook of the Word (LotW).

So, it is half-time! How are we doing?

Well, I can say for one that I have been having a blast trying to work the W1AW-portable operations from Floyd county. With the dipole down, I have been forced to make all contacts with the 160/80/40m trap inverted L. The Floyd county station only has 100 watts (so does Gwinnett county as well, since I blew up the amplifier -- but that's another story).

Sometimes, I've been very successful working stations in every band and mode possible. Other times, it has been very difficult. Just recently, I worked the Alaska operation on exactly one band/mode. One. Conditions just weren't optimal for that circuit. Conditions can also be very weird. I had pretty good success with the W1AW/9 operation in Illinois, working them on all modes from 80-17m. But, I hadn't made any contacts on 15m or above. Then, yesterday morning, I worked them on 15m RTTY early in the morning. Late that the evening, at around 0200-0300z, I worked six more contacts for 15m CW, 12m SSB, and 10m SSB, CW and RTTY. Who would have thought that the band would be open on 10m two hours after sunset?

What's the secret? Well, you have to know how to bust a pileup. Other than that, it's just perseverance. Like working a Dxpedition, early in the week of operations, it is tougher to get through. By Friday or so, it is usually easier. By Sunday, they often are begging for contacts. I temper my patience by calling on Wednesday or Thursday, but I don't waste a lot of time.

And, how am I doing on the whole WARC-band WAS? If you remember, I had no states confirmed on 30m and one each on 17 and 12m when I started. Today, I have 34, 30 and 21, respectively. And there's still more logs to be uploaded from the last month of operations.

So, if you haven't jumped in to the fray, perhaps it is time. Enjoy.

How NOT to Run a W1AW/-Portable Operation

OK, I've been chasing some of the W1AW-portable operations. The light dawned on my back in February, when I realized that these operations could help me achieve WAS on the WARC bands of 30, 17 and 12m.

Managed to work quite a few, some with great ease. Some of it has to do with favorable propagation during the week they were on, but most has to do with the quality of the operators and their scheduling.

Others, I struggled to work at all, and in some cases barely made contacts on some bands. If this is the kind of operation you prefer, here's my list of tips on how to best optimize that outcome:

• Don't operate on the WARC bands. If you're not familiar with them, they are 30, 17 and 12m. These aren't terribly popular, since they have only been ham bands for a couple of decades now. I'm sure some folks don't even have equipment for these bands. Best to stick with the harmonically related bands of 40, 20, 15 and 10m, although I'm not to sure about 15m....

• Don't operate on 160 or 80m, even when it is dark. Rates will certainly be better on 40 or 20m, right. Few hams have the real estate for the enormous antennas required to operate these bands. Best to stay on the higher bands even after the sun goes down -- until the bands close, at least. 

• Don't operate exotic modes, like RTTY. Not many hams will have that fancy RTTY equipment. So, you're sure to work many more stations using good old-fashioned CW or SSB. If you must work a digital mode, make sure it is one of the new-fangled ones, like PSK 63 or JT 65.

• Don't operate split. Takes up too much bandwidth. We hams can't figure out how to set up our rigs for split anyway. Who cares if the rate really stinks, since everyone is calling on top of you. That will make getting the QSO all that much more challenging, right? 

• Don't operate between midnight and 7 AM. We hams certainly need our beauty sleep. They'll be no one to work anyway, right? Everyone should be asleep. And there's no need to start operating early in the morning, especially before sunrise. No one is awake then anyway, right?

• Don't operate more than one band at a time. Hams will get too confuse if you appear on more than one band at a time. Besides, there's probably only one band that's really open, so there's little need to move around.

OK, OK, I kid. I know, these operations are run by volunteers, and not everyone is an expert operator.  It just amazes me at how poorly scheduled a few of these operations were. It was especially frustrating wanting to work these operation on the low bands, and staying up late, or getting up early, only to find they were QRT.

I've slowly been increasing my LoTW totals for WAS from Floyd County. 

W1AW Centennial Operation - The Way To 9B WAS

OK, it took me a month to catch on. I read about the ARRL Centennial celebration. If you haven't heard about it, take a moment to check out the link. What you want to see is the Centennial QSO Party.

I'll wait.

Now, I didn't get very excited about the Centennial Points Challenge. I'm sure I'll work a few points this year just as a natural side effect of operating in contests and other events throughout the year. When I read about the W1AW portable operations from all fifty states (plus US territories), I didn't get all excited either. After all, I already have 6-band WAS. It took the LoTW and many years of work to complete that, doing mostly contest operation, so I didn't make the connection at first.

The W1AW portable operations make it easy to achieve 9-band WAS.

I think it hit me one night when I was looking at spots for FT5ZM. (Great DXpedition, if you didn't manage to work them, well, it wasn't their fault...) I saw spots for W1AW-portable. Some of them were on 30, 17 and 12m.

Now, I said I have 6-band WAS. That's because there are no contests on 30, 17 and 12m. I do operate there, but it's been mostly DXing. I do a little casual style operating with USA stations, but many of these rag chewers don't tend to QSL via LoTW.

I then made the connection -- these highly visible W1AW-portable operations are the perfect way to fill in all the holes in your LoTW WAS confirmations. All of the W1AW-portable contacts will be confirmed on LoTW. They will operate from each state twice throughout the year for an entire week, being on the air virtually all the time. Perfect.

Since then, I've been sneaking into the shack working W1AW-portable on all the bands that I need. I have two award accounts, one for Floyd County and one for the QTH in Gwinnett, so I have a chance to fill in the holes for each.

Don't have WAS? Or need WAS on a hard band like 80m, 15m or the WARC bands? This is your chance. Good luck.

Straight Key Night 2012

Novice transmitter, receiver, and the venerable TS-430S with
the AT-250 auto antenna tuner round out the operating bench.

Yes! Straight Key Night. 2012 makes the sixth year in row I have operated this event. Once again putting  the "Novice" Transmitter on the air, paired with the very capable superhet receiver.

This year, I didn't have any technical problems with either the transmitter or receiver. In fact, they worked pretty much flawlessly (other than the fact that I was missing the stereo to mono adapter for the receiver and had to copy everything with one ear). The interesting thing this year is where they were.

Of course, I had set this equipment up in the Micro-Shack. While not much more than a storage closet, it actually does have just enough room to set up and operate a modest amount of radio.

With a little bit of help from a space heater, it was actually quite cozy during the January 1st operating event. Not much in the antenna department. I believe I favored the low 80/40m dipole rather than the R7000.

As I've written before, being crystal controlled means you have to call CQ. After making a couple of contacts, I decided it would be fun to make at least one contact with every crystal in my arsenal. My ten crystals span the 40m band from 7001.25 to 7121.1 kHz. Some of the frequencies are quite popular, whereas others are pretty far away from heart of SKN activity. Oddly enough, it was the popular frequencies that were the hardest to complete -- they were almost always in use.

I was successful in not only making at least one contact on 7001.25, 7006.7, 7010, 7038, 7042, 7047, 7050, 7061.1, 7075, and 7121.1 kHz, but also making one contact on 10108 kHz. I had just gotten two crystals for 30m this past Christmas, and they tuned right up in the "Novice" transmitter. Of course, the little receiver couldn't be used, so I used the TS430S for that role.

Fifteen total contacts, to twelve different states: VA, MI, FL, GA, TN, TX, PA, MN, IN, AL, NY, NC. My best ever SKN outing.

WARC Trap Dipole

Although I've had good success using an untuned doublet on the WARC bands, I made up my mind that it would be nice to have an antenna that didn't require a tuner.

Initially, I built this antenna has a 30m / 17m dipole. The traps are made from 1.5" Schedule 40 PVC pipe, which is about 1.9" in diameter, wound with RG-59U coax. I built them in much the same manner as those I used later in the 80/40m dipole.

The 17m traps are 35 1/2" of coax wound as 4.8 turns. I trimmed these traps to 18.1 MHz. I actually built three traps, the first was a dummy form so I could figure out where I had to drill the holes to pull the coax down tight.

The 30/17m version uses 12 1/2 feet of wire in each leg, and the outer segments are 8 feet. You may have to trim the lengths to resonate the dipole in the band.

Adding 12m requires two more traps. These were made from 26 1/2" of coax wound in about 3 and 3/4 turns. Trimming the 12m traps right on frequency takes some doing, as small changes in length can shift the frequency of the trap considerably.

I inserted the 12m traps 9 feet 5 inches from the center, and then trimmed the length of the outer legs to bring resonance within the bands. I did not do a great job of measuring -- the 12m traps ended up in slightly different locations in each leg. It does not appear to affect the antenna much.

You should measure the antenna at some height, as the tuning will change as the antenna is raised. I did my initial trimming at 15 feet, and when raised to 42 feet, the resonance frequency rose over 200 kHz on 30m, and slightly less on 17m.

I built a current balun into the center mounting box for the dipole, using 10 type 43 1" ferrite beads, slipped over coax inside the box.

Since the WARC bands as so small, antenna SWR bandwidth isn't a consideration. At 42 feet, there's a little bit of a broadside pattern on 30, more so on 17m and 12m. Since I installed this antenna as an inverted V, the pattern is a bit more circular. The traps can easily handle the 700 or so watts on 17 and 12m.

The WARC bands are a lot of fun with a decent antenna. I've worked several DXpeditions with this dipole on 17m. Without sunspots, there hasn't been a whole lot of activity on 12m yet.

This sort of antenna is easy to build and install. There's no reason lack of antenna should keep you off the WARC bands.