The Challenge of a New QTH

A decade ago, my wife and I spent four years in Floyd County in one of her church postings. We loved the area, and imagined we'd retire there.

In November we took the first step. Bought a house in Floyd County near Rome, GA. House is on the top of a small mountain - Ward Mountain, rising 300 feet above the valley floor below. From the front porch, there is a gorgeous view to the West. On a clear day we can see 35 miles to Lavender Mountain, which is practically in Alabama,

The house is a little smaller than we'd like at 2100 square feet, but there's over 11 acres of land. A small office outbuilding with one room and a tiny bathroom has become the ham shack.

We've owned the house in Gwinnett county for 30 years. Now we are transferring things to the new house. There's a lot to do. We'll sell the Gwinnett house in the next months. In the meantime, I'm focused on building up the Floyd QTH when I have the energy.

Antennas are the first order of business. I first put up an 80/40/20m Trap Dipole. It's up about 12m in the trees. I erected a 160m Inverted-L with two elevated radials. It's a bit noisy, so receiving antennas are likely needed to make the most of that. I plan for three beverage antennas. A 6m dipole barely 4m up in the trees offers me an option on that band.

I've also put together the HF4B. I've mounted it on a 19 foot pole lashed to a deck post. It needs adjustment to work well. It's OK on 10m, but 15 and 20m aren't quite right.

I'm planning to put up a tower. I'll need to take down the tower in Gwinnett first. My plan is 70 feet of Rohn 25, with the A3S/A743 on top. 35 feet below that will be an A3S, pointed at Europe. This would give me a stack toward Europe, plus coverage in other directions with the top antenna. Horizon is unobstructed in every direction except to the NorthEast, where the two additional summits of the Ward Mountain chain are. Those peaks are just 100 feet and 140 feet higher, but they are 1 km and 2 km away, respectively.

I'm already seeing good results with the 80/40/20m trap dipole. There are benefits to being on the top of a mountain. Even a simple tower should be awesome.

For 6m, I'm on the lookout for a 5-6 element beam. The Cushcraft A50-3S i've been using in Gwinnett just doesn't have enough gain to work the intercontinental paths. 

On the office building, I've already moved in an operating desk with desktop shelves, and another luncheon table that serves as a workbench. The main part of the floor is a little more than nine feet square, And almost six feet of the rest of the building is split between the tiny bathroom and the rest of the floor. The desk and workbench are a bit of a squeeze.

A wire shelving rack takes up some of the space opposite the tiny bathroom, and gives me room to store things. I don't know how I'm going to get a whole basement of ham gear into this little building.

Such is the challenge of a new QTH.

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. 

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.

WARC Dipole Repair Complete

Yours truly mounting the antenna near the
top of the tower.

Well, if that didn't seem like it took forever. Back in early September, I took down the WARC Dipole. Although I quickly determined that one of the 17m traps was irreparably damaged, I didn't think it was going to take more than a month before I got the antenna fixed and back up in the air.

I made two new traps using identical lengths (35.5") of RG-58 coax. I didn't bother to try to trim these to any precise frequency. I just made the two traps as identical as I could, and that seemed sufficient.

With the traps back in place I didn't want to re-mount the antenna until I was sure all three bands were squarely in a useful part of the SWR curve. To accomplish this, I used the rope and pulley I had attached near the top of the tower. I used a carabiner through the U-bolt to lift the assembly near the top of the tower.

This actually worked pretty well, as I was able to get the apex of the antenna within a foot of it's mounted height. A 55 foot piece of coax allowed attachment to my MFJ-259 antenna analyzer.

First measurements showed the antenna to be off on all three bands. That wouldn't do. Since I had originally hacked in the 12m traps to a 17/30m dipole, I hadn't done a good job of making the wire lengths symmetrical. This was contributing to bad SWR at resonance. So my first trimming was to make the two legs equal, and subsequent trims were to both legs.

The process goes something like this. Attach the antenna to the carabiner, haul to top of tower. Take rope from one leg and attach it to end of old playground. Pull the other rope through a pulley on the other side of the house until it is above the roof line. Attach the coax to the antenna analyzer, take measurements of resonance and the 2:1 SWR points. Loosen the rope on the side of the house and get the antenna past the roof line. Untie the other rope from the playground. Lower the antenna to the ground. Untangle it all and drag it into the basement so it can be trimmed. Repeat this process.

Honestly, I didn't think I would have to do this eleven times! Both 12m and 17m were resonating slightly low, so I carefully trimmed the 12m portion until resonance occurred in the band. Then repeated the process with 17m. Once each band was in the right place, I soldered the connections between the wire and the trap. Trimming past the trap does not appear to affect the inner doublet, which is what we expect.

30m was a problem. It was resonating slightly high. I ended up splicing in about 14" of wire, split between the two legs. This was too much. In the end, I only needed 3 1/2" added, and that only to one unbalanced leg.

Managed to work ZD7BG just a few minutes after getting this antenna back up on the tower. It's really nice to have a working antenna again. Now the next repair is to figure out what's wrong with the A3S.

Back in the Harness Again

Yours truly on the tower.

When I moved back from Floyd County a couple of years ago, I did a tower inspection. When I got to the top section joint, about 10 feet above the roofline, I lost my nerve. I checked the bolts, then came slowly down the tower. I haven't climbed since. Until today.

I really had to. All the antennas on the top of the tower show signs of being messed up. Mission today was the WARC dipole. While still resonant on 12m, 17m showed no match, and 30m was way out of band.

I took the ends of the dipole loose, you can see two of the traps around my foot level on the tower. Then the climb to the 44 foot level of the tower. The center of the dipole is a NEMA box U-bolted to the tower leg.

Being up there is a little unnerving at first. You try to stay as still as possible, because each move causes the tower to sway.

Of course, as soon as I got up there, I find I don't have a screwdriver. This is why you always use a ground crew. My daughter Lauren did an excellent job in this department.

With the lid to the NEMA box off, took off the U-bolt, and lowered the dipole to the bottom of the tower.

Once back on the ground, a quick inspection showed what was wrong. One of the 17m traps had a clear open, and it wasn't something that was easily fixed. After 12  years on the tower, the shield braid from the trap coax had disintegrated. The trap needs to be rebuilt. It's companion doesn't look much better. In the interest of keeping them symmetrical, I decided to rebuild both the 17m traps. The 12m traps are a couple of years younger, and look to be in good shape.

After I get the traps rebuilt, it will be back up the tower to re-install. And then I need to lower the A3S down so I can check out the driven element -- figure out why I've lost resonance on 15m and 40m is so messed up.

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.

Uh-Oh.

There's that moment -- that moment of pure clarity. The pure clarity that occurs when you realize you've done something really stupid -- something stupid you can't take back.

This happened yesterday. You see, I got off work early and thought I'd spend the afternoon chasing a little DX. I managed to work VP6J on 12m CW, and later they moved down to 17m RTTY. I've never worked Pitcairn using RTTY, so I was watching their frequency closely. They weren't strong, but I went ahead and set up the amplifier on a clear nearby frequency. The day was waning, and I figured if they ever came up a bit so I could get clear print, I'd want to give it my best shot.

In the meantime, I moved down to 30m and worked some other stations. Of course, I switched the AL-80A to standby, and cranked up to 100 watts.

Everything was fine. Until later I went back to 17m to see how VP6J was doing. Their signal had come up a bit, and I could actually read the print well enough to try for a contact. I reached over and flipped the amplifier to operate, and clicked the button to send my call.

That's when I had my moment of clarity.

There was a loud noise from the RF compartment of the AL-80A, along with several sparks, and abruptly, it went dark. An acrid burning smell hung loosely in the air. Certainly, something had gone wrong.

I knew right away what I had done. I had transmitted 100 watts into an amplifier designed to take only 50 watts input.. An amplifier whose original design had not included 17m, and was happier with 40 watts on that band.

Roasted plate choke in AL-80A.

I switched the amp off and then back on, still dark. Clearly, I've blown a fuse. A quick check verified that one of the two 10A fuses had blown. It was replaced, and the amp came back to life. But as it turned on, there was a tiny arc coming from the plate choke. I switched it back off, turned the meter to the HV setting, and briefly switched it on again. The High Voltage looked fine, but I was going to have to get the amp on the workbench to see what was wrong with the choke.

Once I got the cover off, it was easy to see the problem. The plate choke has a black burnt mark. Looking closer, the turns of the choke had melted and separated. The choke would need to be replaced. From the location of the burn, it looks like it had arced from the end of a screw on the plate tuning capacitor to the choke.

I took the tube out and gave it a quick check with an ohmmeter. No grid to cathode or grid to plate shorts, which was good. The Taylor 3-500Z is pretty darn tough, and likely shrugged off the abuse I had just put it through.

Low voltage cap blown to protect meter.

While I had the amp on the bench, I checked out a couple of other things. Looks like one of the protective caps I placed on the B- rail to ground failed. Probably helped to protect the meter movements.

I'll be replacing that cap, along with the 1N4007 rectifier, since it must have gone open for the capacitor to fail. I'll replace it with the recommend 1N5408 rectifier, which can handle a whole lot more surge current.

Melted switch contacts.

Another mystery of this AL-80A I solved -- why it wouldn't tune up on 160m. An inspection of the front switch wafer shows that the switch contacts for the additional plate tuning cap have completely melted away. Since I've never used the amp on 160m, this was not me -- this was an existing problem. The switch contacts, or perhaps the wafer will need to be replaced to restore service on that band.

I ordered a replacement plate choke from Ameritron. They don't carry the original AL-80A part, but instead use a single choke (Part number 10-15197) for virtually all their amplifiers, including the more modern AL-80B. I've read this part avoids resonances on 17m which may be present in the original single-winding choke.

In the meantime, I'll have to chase DX without an amplifier for a while. Perhaps there won't be as many fireworks.

Update: I've been told that part of the problem with the 160m switch contacts is the lack of a corona washer. The picture clearly shows an absence of this part. I'll be adding one when I make the repair.

Sunday Afternoon Dxing

It's mother's day. My wife is taking a well-deserved nap, I've watched all my shows on the DVR, so what to do? I decide I should mosey outside to the shack and see if there's any DX to work. I'm hoping maybe there might be a 6m opening, since it is the Es season.

A quick check of 6m shows nothing happening, so I turn to dxwatch.com and check out some of the bands. I see a spot for V73NS on the west coast on 12m CW. Hmm. Maybe I should listen. At first I hear nothing.  Then, barely above the noise, I definitely hear "73." Intrigued I listen further.

It's just before 5 PM local time. V73NS is definitely in there, and he's calling CQ with no answers. QSB has him coming and going. I drop my call in, he immediately comes back to AA4, but he doesn't have my suffix. A couple more calls, and it's clear he can't hear me as he fades back into the noise.

Noting the QSB, I keep trying. Eventually, as he come back up, he's giving someone a report -- 229. Pretty bad. Oh, wait, here he is again -- he's calling ME with that 229 report. I give him a 559 twice, at the top of the QSB. I get a confirmation. Bingo - in the log it goes.

Wow, just about ESP-level, but a definite contact running over that QSB.

And, today, I get a confirmation in LoTW. Marshall Islands now confirmed on 12m, and CW, and the DXCC Challenge.

It doesn't get any better than that.

Finishing the R7000 Rebuild

At our last installment, we were going to re-assemble the R7000. But, I forget to mention one other rebuild step I performed. When I took the R7000 down, the center insulator was looking green. As in slimy mildew green. Yuck. That growth was going to slowly destroy the insulator.

Refinished R7000 center insulator.

Disassembly was the first step. I thought I might be able to separate the insulator from the aluminum tubes, and I removed the screws holding them together. With the original R7000, there are eight short screws inserted from the inside of the tubes. I'm sure they use some special jig for this, because once you remove them, you can't get them back in. That's OK, because later versions of the R7000 simply used four 2 1/2 inch 8-32 screws.

Even with the screws out, I couldn't separate the insulator from the tubing. It was just too tight a fit to try and separate and risk damaging the insulator.

With all the hardware out of the way, the next step was to clean the green slime off the insulator. Soap and water took care of that with a little gentle scrubbing with a sponge. The fiberglass was a little frayed on the surface, but the insulator looked practically new. 

To prevent a new growth of green goo, I painted the insulator with a thick layer of flat black spray paint. The photo shows the screws re-assembled. 

R7000 Assembled. The chair keeps the
capacity hat rods from bending.

Following the measurements in the manual, I re-assembled the antenna in the driveway. Although the manual directs you to install the radial rods first, it's much easier to work with the antenna if you leave them until later.

Once you put the capacity hat rods on, you'll need to elevate the antenna to keep them from bending. I used a patio chair for this purpose. 

After finishing the assembly, I double-checked the tubing lengths, just to be sure. This is an important step. When I first assembled my Cushcraft A3S, for example, I got the lengths on the director element about 6 inches short on each side.

Before doing all the work of putting the antenna back on the mast, I wanted to make sure it was working correctly. I figured if I could hold it a foot or so off the ground, I ought to be able to see the resonance dips near each amateur band. 

I used a wooden stepladder and bungee cords to  hold the antenna just off the ground. Using an antenna analyzer, I found resonance dips roughly where they should be. Having the antenna so close to the ground means it's going to be slightly out of tune. But it was a good enough test to give me some confidence the antenna would be working as it should. (or, so I hoped)

Wooden stepladder used as a test stand.

After this, I re-mounted the antenna to the mast and raised it back up in position. Initial tests seemed to show good results on 10 and 12m. 15m - 20m were a bit out of whack, and 30m and 40m were pretty much unusable.

Hmm. I contemplated this problem for about a week. I figured it might be a problem with the CT1 trap. In the meantime, however, my replacement capacitor came. I replaced my chain of 4 100 pF caps with a single 27 pF 1 kV capacitor.

After replacing the MN7000, I was shocked to see no SWR dips at all on the antenna analyzer. However, punching the antenna with a little bit of RF remedied that. In fact, the antenna appears to be resonant on each of the expected ham bands with a reasonable SWR.

I used this antenna in the recent NAQP CW. It performed decently. I even managed to hold a run for about a half hour on 40m. I'd say it's now working as  designed. I don't know if it will break any pileups, but having a decent radiator on seven ham bands with one eleven foot support is nice.

Rebuilding the R7000

Given the number of times that Cushcraft has re-designed it's multi-band, no radials vertical, I'm not sure it has been their most successful product. The R5 / R7 designs had problems with trap stability and mechanical complexity, so Cushcraft introduced the R7000, using enclosed traps very similar to designs they used on their very successful trapped tribander series. Later this became the R6000 / R8, where some traps were exchanged for multiple vertical elements. 

The R7000 also went through a trap re-design in mid-1998. There are three different manual available, the original from October 1996, one from June 1998, and the last from May 1999. The latter two are hardly different -- only a slight difference in assembly hardware. However, the 1996 and 1998 versions don't even share the same dimensions.

For those of us using the original version, there's at least one change from the 1998 version that might be worth adopting. When adding the R80 80m add-on kit, there are two tubes BH and BI that are inserted into the ends of the CT1 trap. This strengthened the tubes on the trap, which can help avoid fold-overs like this. The 1998 changes incorporated these tubes as part of the standard product. Since this only requires two pieces of 5/8 inch tubing about 6 inches long, it should be recommended for any rebuild. (Provided you can find 5/8 inch tubing)

First step on any rebuild is disassembly. My unit had seen 15 years out in the weather, but was actually in pretty good shape considering. No parts missing, and only a very slight bend in the bottom of the CT3 trap tube.

When I opened the MN7000, I found several spiderwebs and debris. Getting the circuit board out of the box requires unsoldering the SO239 center contact -- this requires a large soldering gun. Once I lifted the board out, I was surprised to find a very live spider who was not happy I disturbed his home. Sorry, fellow, but the eviction has been posted.

MN7000 after re-assembly.

I found the MN7000 in pretty good shape. None of the components seemed charred, cracked or damaged. Some of the connections on the circuit board showed a bit of corrosion, and I re-soldered some of the connections. 

Unfortunately, in trying to shorten the leads on the 27 pF capacitor, I ended up destroying it. In the picture, you can see my substitute -- four 100 pF 50V capacitors in series. As soon as I get the correct part, I'll swap these out.

Pay attention when disassembling the MN7000. I found some of the hardware to be slightly corroded, along the brackets. Remove as much of this as practical.

The general advice is that high SWR on all bands means an MN7000 failure of some kind -- but I couldn't find anything wrong, other than a few questionable connections.

Not sure if the MN7000 was the problem, I turned my attention to the traps. After a short debate, I decided to disassemble all the traps. 

CT3 trap disassembled. The 20m trap is on the bottom
(right) of the assembly, and the 30m trap on the top (left).

The traps consist of two nylon bobbins that are held inside the aluminum tubes by four self-tapping screws and four dimples. You have to drill out the dimples with a 1/8 inch drill bit. The top rubberized weatherproofing was removed by slitting it part way up the non-connected side (the smaller lump) and pulling it off. Try to cut as little of the weather proofing as possible. Remove the screws and pull the bobbins out, or you can tap them through (but be sure to move the aluminum wire out of the way).

CT2 trap half-way assembled. 15m trap is inside the tube,
17m trap waiting to be installed. 

The traps were in pretty decent shape. The top trap bobbins were clean, with the bottom trap showing a bit of insect debris. The bottom traps showed a bit of yellowing as well. A few checks with an ohmmeter showed the connections between the wire and inner trap tube were good. 

Re-assembly was easier than disassembly. Since the dimples were drilled out, I substituted 3/8 inch long #6 self-tapping screws. The alternative would be to cover the dimple holes with tape, but using screws seemed to add to the structure of the trap.

CT1 trap, reassembled on the antenna with a protective
layer of electrical tape.

Weatherproofing is held in place with a layer of tape, wound from the bottom to the top. I also added a layer of tape over the bottom screws, in order to keep the weather off the aluminum wire connection.

With all the components cleaned and re-assembled, it is time to assemble the antenna. Which we will do in our next installment.

R7000 Moves to Micro-Shack

Putting up the R7000 at the Micro-Shack took a bit of doing. I didn't want to leave any concrete monuments in the yard, so I had to look for something a bit more temporary. Fortunately, there's an outbuilding behind the house that appears to be made of salvaged lumber. This little shed has seen better days, but looked sturdy enough to support wall brackets. A few 2x4 reinforcements inside the framing received lag bolts for a couple of wall brackets I had on hand.

The hard question was -- what to do for a mast? The 1 1/2 inch rigid EMT I used worked ok for 15 years, but EMT isn't meant to be a mast product. Plus, it wasn't the right outside diameter to fit the mounting U-bolts for the antenna. A 12 to 15 foot piece of 2 inch galvanized, chrome-moly steel would have been ideal, but not easy to come by.

Top end of mast, showing R7000 attached. Notice the R7000
radials are not installed. They get in the way so it is easier
just to put them on just before raising the antenna.

I ended up using an different combination. First, a 10 foot piece of 1 1/4 inch steel pipe, a 1 1/4 to 1 1/2 inch adapter, then a 12-inch long 1 1/2 inch steel pipe nipple, and finally a pipe cap. Steel pipe is quite a bit thicker than rigid EMT, and a lot more expensive. A 10 foot 1 1/2 inch pipe would have been almost $40! The 1 1/4 inch pipe was just over $25, and the 1 1/2 inch nipple made it 11 feet total height. 

The 1 1/2 inch nipple fit the mounting U-bolts much better than the old rigid EMT did. Close, but not as perfect as a 2 inch mast would be.

It just took a warm afternoon to put up the brackets, assemble the antenna and raise the mast. Unfortunately, the antenna did not show the characteristic low SWR on the ham bands. Some work with an antenna analyzer showed relatively high SWR on every frequency from 7 to 26 MHz. Only on 10m did it show a slightly lower SWR of about 3:1. 

Uh-oh. Looks like this 15-year-old antenna needs a rebuild.

R7000 History

After my move in November 1994, it took over a year before I put up any antennas -- I was much too busy with young kids, new job, finishing the basement, etc. In January 1996, I put up a 125 foot doublet up about 15 feet and operated the NAQP CW contest. That doublet got mounted higher by the NAQP phone, and was joined with some attic antennas.

By the fall of 1996, I was in the market for an antenna that could reasonably support several bands, including the WARC bands. The R7000 seemed like a pretty nice solution -- seven bands with an option to  add 80m as well. I bought one in November of 1996.

To mount it, I joined a 10 foot piece of 1 1/2 inch rigid EMT to a 12 inch steel pipe nipple and planted it 3 feet in the ground using two sacks of concrete. The pipe union was buried in the concrete. The resulting vertical pipe was about 1.9 inches in diameter -- almost large enough to fit the mounting U-bolts -- and nearly 8 feet tall.

While not as optimal as the specified 2 inch mast, this support worked very well for 15 years. I only stopped using the R7000 a couple of years ago when the coax to it was cut when the cable company re-buried the cable. (That one was cut by septic tank workers repairing the system)

The R7000 was not a great performer, in my opinion. I first called it the R7000 attenuator. I later discovered that it was designed to work at a height of 18 feet, not the 8 feet I had installed it. After a few years, I got the idea to add some radials at the base of the mast. Seven 20-foot radials made the antenna appear to work a lot more reasonably.

Since I wasn't using it at the old QTH, the R7000 seemed like the perfect antenna to move to the Micro-Shack. It required only one support, covered seven bands, and with a few radials seemed to work OK. A mediocre antenna seemed better than none at all.

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.