Beverages -- The Big Mix-Up

Can you spot what is wrong in this picture?

No, this is not like ordering Coke and getting Pepsi. This is a bigger problem. Not a drinking beverage, but the receiving antennas designed over 100 years ago by Harold S. Beverage.

Last winter, I wrote about erecting three Beverage antennas to the NE, NW and SE on my property. Each is 500 feet of wire. For each I built small plastic boxes containing terminators and transformers for the beverages. 

The antennas I put up impressed me. Noise levels were easily 1-2 S-units below the transmitting antenna, and I could hear and copy stations that were not copiable on the transmitting antenna. I managed to add four new countries to my DXCC totals on 160m. 

They were working great. Or so I thought.

Regular Maintenance

Since I've been sick with my liver infection, it's been hard to keep up with the required antenna maintenance. I noticed a month ago that the NW beverage feedpoint and first 30 or so feet of wire was lying on the ground. My friend Renee noticed that the NE beverage was touching the ground as it headed down the crest of the ravine. We didn't manage to fix these until this week.

The NW Beverage had a failure of the insulator at the feedpoint. I replaced the single insulator with two, which should give better support. Also, I changed the angle of the tensioning rope so it was more in-line with the antenna. We walked the first 100 feet of the antenna, and was able to spot the next 75 or so feet, and everything looked copacetic. I'll save walking the entire Beverage for another day.

The NE Beverage had a similar problem -- the insulator right at the crest of the ridge had failed. Replacing it was easy. Working about 75 feet back toward the feedpoint, we also added a rope catenary to support the Beverage where it passed too far away from trees to mount an insulator. This largely solved the problem with the pull we saw at the feedpoint, and re-adjusted the tension rope.

At some point, Renee had asked "What's in the little black boxes?" When we got back into the shack, I showed her. Although I erected only three Beverage antennas, I built enough termination and transformer boxes for five Beverages. The transformer box was easy enough to explain. I had to pry open the terminator box to get a view of what was inside.

The Huge Error

When planing my beverages, I gathered the best possible information and built everything accordingly. Tom Rauch, W8JI recommended the use of metal-ceramic composition resistors for the terminators -- specifically the Ohmite OY series devices. These guys were not cheap, costing over $2 apiece. But they had the best qualities -- non-inductive, low-noise and durable in the presence of overloads due to lightning strikes. So, that's what I ordered about a year ago.

Take a close look at the picture at the top of this article. Notice anything? I've known how to read the resistor color codes since I was about 9 years old. You'd think that 55 years later, I would have noticed these resistors are Yellow-Purple-Yellow-Silver. That's nominally 470,000 ohms. Not the 470 ohms they are supposed to be. 

Once I noticed this, I opened the other termination box I had, and it held the same resistor. I went back and reviewed what I had ordered from Mouser -- sure enough, it was the Ohmite OY474KE resistors - 2 Watt, metal-ceramic composition resistors of 470,000 ohms, with a 10% tolerance. 

My terminator boxes weren't terminating at all -- the resistors were a thousand times too large.

Why Did They Work At All?

My next question was easy -- if the resistors are wrong, then how did the Beverages work at all? Why did they show clearly 1-2 S-units lower than the transmitting antenna? And how did they fool me into thinking they were working great?

The answer is simple. With such a high resistor value, my Beverages were basically unterminated. This means they were bi-directional -- receiving equally well along the line of the antenna, and less so at right angles. Therefore, there was some reduction in noise, but not nearly as much as there should be with proper termination. 

I have ordered proper OY471KE resistors. Let's hope they get here soon. I can't wait to hear what proper termination sounds like.

Demise of one 80/40/20m Dipole

I was QRV in Gordon county briefly - only a couple of weeks. I managed to erect the 80/40/20m dipole I had up in Warren county, which previously flew over Fulton county. It was a cobbled-together mess, made from wire left over from the original 80/40m dipole, newer traps, and old insulators and rope.

Using the Mark III Antenna Launcher, I did a good job casting over a tree in the front yard. Weight sailed up over the tree and came right down beside the trunk. The 1/16" guide line went back out to the antenna launcher, and then the 1/4" nylon halyard came back over. Perfect.

At the far end, I had more trouble. Not wanting to crawl over a fence, I cast sideways to branches overhanging the edge of the yard. The first toss wasn't great, so I pulled it down. Second toss got stuck in the tree, and I lost the weight. I was down to my last antenna weight. I confidently tied it on, pulled back, let it fly, only to watch it sail off the end of the fishing line and into oblivion. Nuts. 

With no weights handy, I couldn't use the antenna launcher. I opted to use a small hammer and toss the halyard over a branch about 20 feet up in the tree. At least I didn't lose the hammer. 

The resulting installation sloped the dipole from about 25 feet on the south end, to about 60 feet on the north end. No matter - it would work. At least, until I could make more weights and get it higher in the air. 

I used it to make about 100 contacts for the NAQP Phone in August, plus a little casual operating. Then I found most of it lying on the ground after a few windy days. Inspecting the remains showed that the wire between the 20 and 40 meter traps had broken. That particular segment was pretty old, being part of the original 80/40m dipole, and might have used wire from the ancient untuned doublet before it.

This meant that one of the 40m traps was still up in the tree. Looking carefully, I could see it about 50 feet up. Untying the rope, I could not get it to drop, and instead pulled the halyard to recover the rope. The wire ended up coming off the insulator, leaving wire and one trap stuck in the tree. Drat.

The rest of the antenna lay across the yard and lower driveway. I don't use that driveway, so I didn't think about it. However, some folks came to visit the parsonage and apparently didn't see the traps laying there. Two of the trap forms got crushed in the process. Doggone it.

I guess I have to rebuild this antenna from scratch, using new wire and traps. That will take some doing, as most of the parts are back in Gwinnett county. Plus, I have to make more antenna weights to put it back up. 

In the meantime, I'm off the air in Gordon county.

A3S/A743 Refurbished - Rotating Once Again

A3S/A743 QRV @ 15m

Since I took it down back in October, the A3S/A743 is once again proudly back at the top of my tower. It's been something of a long ordeal.

Refurbishing the antenna was delayed when I had to wait eight weeks to get traps out of MFJ -- they, like many companies have been greatly affected by the Coronavirus. Indeed, their biggest problem is getting parts from their suppliers, who are likewise affected.

Even after getting the parts, I had a lot of trouble tuning the A3S somewhere close to the bands. That required a lot of jockeying on the tower. It did give me a lot of time at the top of the tower, something that is always a confidence-builder.

I had a little trouble with the rotator yesterday -- one of the connector lugs came off the pigtail. This meant that while the rotator was in place, it wouldn't turn. I was tired from the long climb yesterday, and fixed it today. 

The good news is the antenna seems to be working correctly. I haven't worked a lot with it, but I'm sure I'll get a chance during the RTTY Roundup this next weekend. 

Hopefully, this antenna should serve me well for many years to come -- the initial installation worked for over fifteen years. Fifteen more would be fine by me.

Next project will be to fix the WARC trap dipole and put it back up.

Re-writing the K9AY Controller

 I was quite happy earlier this month to get the K9AY Loop Controller working. After using it in the ARRL 160m contest, I decided I needed to make some changes to the firmware.

That presented a problem. You see, while Microchip has made some excellent developer tools available for their PIC series of microcontrollers, like all software, it is updated from time to time, and things change.

When I used MPLAB X three years ago to write the controller firmware, I used the PIC assembly language tool MPASM. That was with version 3 of MPLAB X. I recently updated to version 5 of MPLAB X, and MPASM was no longer supported. Instead the new assembly tool was called pic-as. And, of course, it was syntactically different than the old MPASM.

I made an attempt to edit my existing code into something acceptable to pic-as. While I got it to build, I found it didn't run correctly. Rather than try to debug, I figured it might be easier to start over.

Microchip has a good C compiler. I decided to start there. I'm well experienced with C, but this left open a lot of questions. The PIC has a number of configuration registers that must be set at startup. How does one do that with C? 

This actually turned out to be very easy. Microchip has a tool called the MPLAB Code Configurator (MCC). It provides a number of graphical tools and wizards that specify the chip configuration, down to the pin assignments and interrupts. MCC then generates the appropriate C code. This is a good thing. One of the hard parts of working with the PIC is figuring out how to set all the internal registers. MCC does this part for you.

My second question had to do with interrupts. How do we process interrupts in a C program? This also turned out to be easy, because MCC generates code to handle interrupts, too. When properly configured in MCC, one need only write a simple void function to process the interrupt. My controller uses a timer interrupt every 2 ms to check the state of all the buttons and update the LEDs and relays appropriately.

Re-writing the controller program in C ended up taking less time than figuring out the assembler syntax changes between MPASM and pic-as. 

And the best part is, it worked! 

Tuning the A3S/A743

Adjusted A3S/A743, ready for rotator.

After adjusting the A3S/A743 on the ground and getting it back on the tower, I was very disappointed to find the SWR dips for each of 10, 15, 20 and 40m were all outside the band. They were all too low. This surprised me. When I measured the antenna with the beam facing upward, the dips were very close to the band. Now that the antenna was on the tower, it was going to be more difficult to adjust.

Rick Dougherty, NQ4I, gave me an important tip. Always measure horizontal antennas horizontally. Don't attempt to make measurements with the antenna vertical. With the antenna 6-8 feet off the ground, you can get a good sense of the measurements, knowing that the antenna will rise in frequency as it moves away from the ground. Generally by about 100-300 kHz at the 30 or 40 foot level. As you move further from the ground, the effect lessons. 

Rick knows his stuff -- he built a superstation in Griffin, GA, and has experienced this phenomena putting up dozens of antennas. 

OK, I didn't follow Rick's belated but sage advice - what should I do now? I didn't want to take the antenna off the tower again, it was a lot of trouble to get it up there in the first place. I decided I could make adjustments similar to how I added the A743 option originally - by tipping the Driven Element (DE) vertically and climbing down the tower.

On the tower adjusting
the now vertical DE.

One the first climb to make adjustments, I could already see part of the problem - some of the DE joints had slipped outward while the antenna was waiting to be installed pointed vertically. The extra weight of the A743 parts probably had something to do with this. 

Loosening the U-bolts for the DE and the support mast, the DE tipped over easily and I was able to climb down the tower and adjust. I had to make some of the adjustments somewhat blind, since I could not easily put a measuring tape against the elements. 

I ended up with the 10m traps out about 83.5" (A), the 10 and 15m traps spaced as 6" (B), and the 15 and 20m traps at 18.75" (C) -- this was the lower limit, since the tubing ends were contacting each other inside the support tube. the 40m portion I extended to about 66". These measurements are for each side of the DE.

This took two climbs, and ended up with the 10, 15 and 40m SWR curves well centered in the bands, and 20m right at the bottom of the band. This isn't perfect, but it is usable. Note I did not make any adjustments to the Reflector or Director, as they are well out of reach.

Next time I set up an A3S/A743, I think I will adjust the 10 and 15m portions to the MID-band settings, and split the MID and CW settings for 20 and 40m. That's roughly where I ended up anyway. 

I'll also consider replacing a lot of those stainless steel worm clamps. After being out in the weather for 30 years, a few of them would not tighten the way I would like. 

The A3S/A743 should be ready to go after one more climb to raise the antenna and install the rotator. I also plan to tweak the support mast a bit higher to keep water from accumulating in the 20m (TK) traps, since that's likely how they failed in the first place. 

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.

K9AY Controller and Antenna

K9AY Controller at operating position.

In 2007, I put up some K9AY loops. They were a little less than half-sized, about 33 feet in each loop. They worked pretty well on 80 and 40m, although they were a little weak on 160m. After about three years, they stopped working. At the time, I was using a rotary switch to change directions, but I really wanted a push-button controller.

In 2015, I designed a controlled based on a 74LS175 Quad D-type flip-flip. It was pretty simple in concept, but, it didn't work. The bounces from the switches changed directions rather randomly.

Which lead me to write this article, about a solution - using a PIC micro-controller to solve the bouncing switch problem. 

I built that prototype, and wrote about it three years ago. One problem was that the wiring appeared flaky, it wasn't always dependably switching. I figured I needed to design a PC board. 

While I've been working on that, I had a thought a couple of weeks ago -- maybe I could piggyback a second piece of perfboard to my prototype and keep the board from flexing, and that would avoid the flaky wiring. Easy enough to try.

K9AY Antenna box
at base of tree used as
support

Sure enough,  doubling up the perfboard helped. I determined that the wiring wasn't that flaky. Part of the problem was that the NW and SW switches and LEDs were reversed. Pressing the SW button sent the NW voltage, and vice versa. 

With that fixed, I couldn't find any reason not to put the K9AY back up. I used 42 feet of wire in each loop. This is a good compromise length for 160, 80 and 40m. 

Some on the air testing shows that it works pretty much as expected, and the push-buttons make it really easy to change directions. 

Schematic for the Little 40m Receiver

I'll admit that it has taken far too long for me to publish this schematic. I wrote the original article about a small solid state receiver in January of 2009. I promised a schematic, but I never published it. 

The original sketches of the schematic are too embarrassing to publish directly, so I had to re-draw the schematic neatly.  I started on it last summer, but I finally finished it very recently. 

Just click on the image to the right. 

A couple of notes on the schematic.

The IF Out label on the right side of the page connects to the IF Out label in the lower middle of the drawing. 

I didn't have a 7808, so I used a 7805 regulator with a stack of four 1N4001 diodes that gives about a 7.5 volt supply. You could use a 7808. In fact, I purchased one a while ago, but I've never modified the rig to use it.

You might have to adjust the values in the S-meter circuit if your meter movement isn't a 600-ohm 250 uA device like I used.

I don't have a block diagram, but the sections are straightforward:

• SA612 Mixer / Oscillator
• Crystal ladder filter
• MC1350 IF Amplifier
• SA612 Product Detector / Oscillator
• LM 386 AF Amplifier
• LM 358 AGC Amplifier / S-meter driver
• 2N3906 Mute driver

I built the rig in stages, starting with the AF Amplifier, then the Product Detector, IF Amplifier, Crystal Ladder filter, Mixer. I then added the AGC Amplifier and the S-meter driver, and finally the mute driver. 

The Crystal Ladder filter is based on 4.915 MHz crystals. The Oscillator is 7 MHz above that, nominally tuning 11.915-12.065 MHz. I've been thinking about adding a switch with a different oscillator and bandpass coil to cover 30m. 

Rebuilding the A3S/A743

I've had the A3S/A743 down for several weeks now. I've gotten it mostly rebuilt, but I'm waiting on parts. More about that in a moment. 

I wrote previously about my inspection of the traps. The 20m TK traps are completely toast. But the TA (10m), TB and TC (15m) traps appeared to be fine. All the plastic end caps, however, were toast.

This particular A3S/A743 has been up for a while. I originally purchases the A3S in 1991. It spent three years in the air at the old Stone Mountain QTH, then several years in my basement in Gwinnett. Then it spend a couple of years on W1YM's tower while he was waiting for his Skyhawk to be delivered. And nineteen years at the Gwinnett QTH. All told, that's twenty-four years exposed to the elements. The A743 40m option has only been up fifteen years. 

A few years ago, I bought another A3S at a hamfest for $100. Such a deal! This unit was manufactured in 2007 and does not appear to have been outside for any length of time. The plastic end caps on the traps look practically new.

During the rebuild, I decided to use the TA, TB, and TC traps from Cushcraft #2 on the Cushcraft #1 tubing and vice versa. Cushcraft #2 isn't going up any time soon (perhaps when I move to another QTH and can build a 70 foot / 35 foot stack). I figured I would use the least weathered traps on the antenna that I'll be using. 

I used No-Al-Ox liberally when I assembled the A3S nearly twenty years ago. After nineteen years in the weather, much of the original application had evaporated, but the sections came apart easily after unclamping. The traps from Cushcraft #2 had never seen a drop of No-Al-Ox, unfortunately. So, as I intermixed the parts, I made sure I applied some to every joint. 

I ordered all new trap end caps, boom and element end caps from MFJ, along with new TK traps. Laird communications sold off Cushcraft several years ago to MFJ. I was happy that parts were still available. However, the ordering system left much to be desired. MFJ is in the middle of a web site re-design, and there's no way at present to order individual parts. Their older web site would list parts on the same page as the product, and you could click through to the parts link to order each one. Why they would switch to a new web site that doesn't have this capability is beyond me. 

A call MFJ with all the proper part numbers, I ordered everything pretty easily. Then it got weird. The gentleman on the phone didn't tell me the total of my order, he just guessed it would be $130-140, which is about what I expected. He estimated my order would ship in two weeks, and that I should see an order confirmation email and another email when the order shipped. All good, I thought.

Then I noticed my credit card was charged $169.90 almost immediately after I got off the phone. I waited a few days, but I received neither a order confirmation or shipping confirmation email.

This is not right. Indeed, this may be illegal. You're not supposed to charge someone for an order unless their goods have shipped. That's how it is supposed to work. I called and asked about it, and they said they corrected my email address and I should get a confirmation. My order hadn't shipped yet, because the TK traps needed to be manufactured, and that would take at least two weeks. Fine. But, then I didn't receive any order confirmation emails. A week after my original order, I called again, had my email address corrected again, and asked that a confirmation email be sent. This time, I received it. At that time, I was told my order would ship in ten days. 

And, sure enough, ten days later, they shipped something. I was surprised when I received a very small box -- clearly not large enough to contain the two TK traps. Opening it, I found my entire order of plastic end caps. But no traps. 

It's now been four weeks since I placed my order, and no indication they are shipping the traps that take them two weeks to manufacture. There have been at least two good weekends for putting the tribander back on the tower, but without traps, I can't finish the assembly.

Keep your fingers crossed I actually see these traps sometime soon.

A3S/A743 On The Ground

A3S/A743 on the ground

I've known for some time now that my A3S/A743 has problems. Back in March 2019, I noticed that one of the 20m traps was arcing. Then a couple of months ago, I could see that several of the trap end caps were either missing or damaged. 

It's taken me several tower climbs to bring this antenna to the ground, but this weekend, we were finally able to successfully lower it down without incident.

My daughter Lauren acted as my ground crew and did an excellent job. I couldn't have done it without her.

Antenna mounted on tripod

Once the had the A3S/A743 on the ground, the next process was to carefully mark, measure and inspect the antenna. I didn't want the antenna lying on the ground. I had a roof tripod I'd picked up somewhere along the way, and with a short piece of mast, it allowed me to work on the antenna horizontal at ground level.

As soon as we had the antenna on the tripod, I marked all the traps. The original Cushcraft trap markings weather off rather easily. I used a sharpie to indicate the element, trap band, and an arrow pointing toward the boom. It will be important to reassemble the antenna with the traps in the correct direction.

DE traps showing disintegrating
end caps.

Next step was to mark all the element distances. This just required a quick sharpie mark at each tubing junction. 

After this, I got out a clipboard and a measuring tape, and took measurements of all element segment lengths for all three elements. I wanted to see how the antenna measurements matched up with my records. As it turns out, even after 19 years in the weather, the director and reflector elements were spot on. The driven element was a little asymmetric -- that likely happened when I added the A743 kit in 2005. 

DE support rope covered 
in lichen.

With the marking and measuring done, it was time to inspect the antenna. Overall, all of the aluminum tubing appears to be in fine shape -- nothing bent, warped or cracked. The traps were a concern. All of the trap end caps were either missing, damaged, cracked or weathered. Three of the element tips were missing, even the boom end caps bad broken. 

My daughter Lauren noticed the lichen growing on the antenna. Lichen covered a few trap end caps as well as the entire DE support rope.

I was surprised to find the bead balun in such good shape after 19 years. The feed line it surrounded seemed rather weathered, and it is my intention to replace it.

Next, I disassembled the antenna. Because I used No-Al-Ox 19 years ago, separating the sections was easy. Once a clamp was loose, they slid right off. I removed the traps and outer sections, leaving the center part of the elements intact. The outer sections I stored in my basement, and the traps went to the workbench. The boom and center part of the elements, I lashed to my back porch for now. 

With the outside work done, it was time to inspect the traps. I pulled all twenty-eight end caps off. Maybe four or five were intact, but even those are heavily weathered. I blew all traps out with compressed air, finding surprisingly little material come out, which I took as a good sign.

The two 20m (TK) traps were a concern. These traps I saw glowing back in March 2019. One of the end caps had melted. With the end caps off, I could see the outer end insulator on both traps had melted.

Only a little char on this one.

To know how bad it was, I had to disassemble the 20m traps. Disassembling these traps is a difficult proposition. The outer end of the trap cover is dented inward in four places to hold on to the end insulator. Because of this, it can only slide outward. The inner end of the trap cover has a double-z bend to make connection to the element tubing. If you undo the bend, the cover will slide off outward. But undoing the bend will likely break the aluminum. 

A lot of char on this one...

For the 20m traps, the outer insulators were toast anyway, so I didn't have any trouble sliding the trap cover inward. I just had to remove the screw at the double-z bend first. 

What I saw inside was not pretty. Both traps were damaged due to arcing and will need to be replaced. 

I also disassembled one of the 15m DE traps. Of course I broke the double-z bend in doing so. However, the inside of the trap looked clean, and, unlike the 20m trap, the coil windings were protected with resin. I didn't think it was worth disassembling any more traps and breaking more double-z bends.

I believe the 20m traps may have suffered from too much droop on the elements and collected a lot of moisture inside the trap. Once fired up with RF, it arced and toasted the traps. 

Some of the traps had corrosion evident around the hold-down screw on the trap covers. I removed the screw and put a thin layer of No-Al-Ox between the z-bend and the trap element tubing. This should limit further corrosion in this joint.

80/40/20m Trap Dipole

80/40/20m dipole strung from tower.

I've had good experience with trap antennas. I built an 80/40m trap dipole a decade ago, and it served me well at four different locations. That is, until it met an untimely demise when a rope was cut and the mowers encountered the antenna on the ground.

Wanting to build a three-band dipole, I did some experiments with computer modeling. I found that there was a lot of interaction between the values used for the traps and the wire lengths used. I fussed around with a model for a while. Eventually, I decide it would be simpler to just build one.

I started with the traps. They are made from short sections of 3" schedule 20 PVC. (Having an outer diameter of about 3.25") The exactly frequency of resonance doesn't matter terribly much, just so the traps are identical.

For the 40m traps, I used 9.75 turns of #12 wire with a 56 pF 6 kV disc ceramic cap. This resonates at about 6.88 MHz, just below the band. I started out with 10 turns, but they resonated around 6.5 MHz, which was too low.

On 20m, 6 turns of #12 wire with a 27 pF 6 kV disc ceramic cap. Resonating at about 13.84 MHz, right below the band.

Early version of traps, showing construction.

I then put it together to form a dipole with the following segment lengths on each side:

20m: 17 feet
40m: 17 feet
80m: 20 feet

This made the whole antenna nearly108 feet long. The ends of the 80m segment are looped back on themselves by about a foot and twisted to anchor to the end insulator. I strung it between the tower and some trees in the back yard. It's roughly 10m high. 

The dipole is fed with good quality RG-8X using 16 Fair-Rite #43 1/2" ferrite beads as a current balun. 

Then began the tedious process of trimming to resonance. I started with the 20m segments, then worked out to 40m and finally to 80m. Patience is warranted here, because it is too easy to cut too much off.

I ended up with these segment dimensions, resonance points and SWR:

20m: 16' 4" - 14.125 - 1.45:1
40m: 10' 4 - 7.165 - 1.2: 1
80m: 21' 8" - 3.76 - 1.1:1

And, yes, I added 20" to the end of each 80m segment. The resulting antenna is about 96 feet long. It covers all of 20m and much of 40m with a 2:1 or better SWR. 80m, by comparison is very narrow. I didn't have much of a chance to use the antenna, but it appears to hear very well. 

I've got a second one I've cobbled together for the Fulton County QTH. I'll need to wait until the tree lose their leaves so I can get it up to operating height for final trim. 

OK, That's Not Good

Noticed today while I was mowing grass that two of the traps on the A3S/A743 -- the 15m trap on the director and the 20m trap on the driven element -- both have end caps that have come off the traps. 

This means the traps are exposed to the weather, insects and what not. 

That's not good. 

Indeed, from the ground, this antenna isn't operating correctly, either. The SWR is over 2 to 1 on 15 and 10m, and the antenna doesn't seem to be that effective on those bands, either. Only a little bit better on 20 and 40m.

The A3S has been up since 2001. I added the A743 in 2005. That's been 15 to 19 years exposed to the elements. It's not surprising this antenna needs maintenance.

I've got the gin pole on the tower, just need a couple of days at the Gwinnett QTH with a little help to get that antenna on the ground.

Replacing the AL-80A Bandswitch

The AL-80B bandswitch, compared to the existing switch shaft.

With my wallet being $115 lighter, the AL-80B bandswitch arrived within a week. Now, it isn't the same as the original AL-80A bandswitch.

There are two key differences. First, as you can see from the picture, the shaft layout is different. In the original AL-80A bandswitch has the input network switch wafter in front of the bandswitch, whereas the AL-80B has it behind the bandswitch.

This means you can't just replace the AL-80A switch with the AL-80B switch. The best you can do is to unstack the wafers and put them on the original AL-80A switch shaft.

AL-80B switch with AL-80A wafers.

The second difference has to do with the switch wafers. Electrically, they are identical. The AL-80B switch has the 160m padder cap and the Pi-L network wafers reverse. Since we're going to re-stack the wafers anyway, this doesn't matter.

The Pi-L wafer is positioned differently. The contacts are two positions counter clockwise (as viewed from the front of the shaft) from the AL-80A. This means that a bit of re-wiring is necessary to make the connections.

Wafer-less switch.

Removing the switch wafers isn't a big deal, since I have done this earlier. The rear wafer comes off with all the coils attached, and the padding caps unscrewed, there being only one wire that needs to be unsoldered, and it slips off. The middle wafer has a similar wire to be unsoldered, and it comes off as well. The front wafer has one wire to the padder cap, and it comes off as well.

With all the wafers off, the new switch wafers are stacked on. Because the Pi-L wafer has contacts rotated two positions, they are a little harder to access between the switch and the loading capacitor.

New wafers in place.

Once all the wafters are on and screwed down, the next step is to re-solder all of the connections. I took lots of pictures before unsoldering the old wafers, so I had a pretty good idea of what goes where.

Front switch wafer anchors the coax shield, and adds the 160m padder cap. The Pi-L switch wafer was the only one that gave me trouble. Since the contacts are rotated from the original, this required a bit of extra wire to make the required connections. The rear switch wafter has five connections tot he coil assembly. It took a bit of work to unsolder. This sort of thing is best not rushed and done with great care, to avoid damaging the coils. Everything goes in the same place on this last switch wafer, which was easy once I got all the coil wires into the right positions in the narrow switch contact lugs.

The finished product. Reassembled with new switch wafers.

Sounds easy, eh? But realistically, it was nearly three hours on the workbench.

Moved it back to the operating desk and tested for full output into a dummy load on all bands. No problem on 160, 80, 40, 20, 15 and 10m.

For 17m and 12m, I proceeded more cautiously. The AL-80A is designed to operate on 12m using the 10m switch position. It works on 17m using the 20m switch position. But it has often been on 17 or 12m that I've had the most issues with arcing in the PA circuit.

For this reason, I've decided to reduce drive to about 30 watts for 17 and 12m. It's a little less output power, but also less of a chance of burning up a $115 bandswitch.

With the testing done, it was time to button up the amp. Took me about 20 minutes to find 10 of the 13 screws that hold the cabinet top on. I had removed them a year and a half before, but finally found them in a neat pile on the workbench.

The AL-80A is back up and running on all bands!

Digging back into the AL-80A....

Front switch wafer - showing contacts burned
completely away.

Back in July of 2018, I was chasing the KH1/KH7Z expedition on 17m, and the AL-80A stopped producing any output. I dug into enough to find that the Pi-L output switch contacts had arced and burned. So, I jumpered the switch so the amp was only usable on 40m and above. And it has worked OK since then - but not on 80 or 160m.

It's way past time to fix this, so I recently got started. I figured that I just needed to replace a switch contact or two like I've done before.

Back side front switch wafer showing more
contacts completely burned away.

Once I got the lid off and removed the switch wafers, well, the photographs tell the sad story.

Middle switch wafer. You can see my jumper
between the to contacts on right. There was not
enough material on the switch wedge to make
contact with the 40m contact.

Replacing the contacts won't be enough. Plenty of the switch wiper was gone on the Pi-L (middle) switch wafer -- especially the corner that used to short out the Pi-L coil on 40m. And the 160m padder capacitor (front) switch wafer isn't any better.

No, this means I'll have to replace the switch entirely. I've ordered one from Ameritron, with shipping it came to $115! This is the AL-80B switch, which is similar, but not identical.

Schematic for the "Novice" Transmitter

Schematic for the "Novice" Transmitter

I guess it has taken a while. I wrote about my Novice transmitter over ten years ago in January of 2019 as one of my first articles in this blog. But I never published a schematic.

Well, the wait is over. This summer I took some time to hand-draw a schematic reasonably neatly. At least neatly enough for someone else to make heads or tails out of it.

The result is in the image on the right. The circuit is pretty simple.

A couple of notes on the tank circuit. The coil is 1 3/4" diameter, 12 turns, about 7/8" long, which computes to be about 6.4 uH. A typical pi network for a 6146 at 7 MHz should be L = 6.2 uH, C1 = 90 pF, C2 = 500 pF. So it seems my design is pretty close.

The keying arrangement is unique. The oscillator is cathode keyed, but the PA is biased beyond cutoff for Class C operation. When properly the grid tuned circuit is properly adjusted, there is little to no chirp.

This radio works pretty well on 30m, too. The crystals I have for 30m are HC-49U crystals soldered in FT-243 housings. These drift a little bit key down, likely due to the high crystal current. I added a 100 ohm resistor in series with the crystal to limit the current.

Demise of the 80/40m Dipole

Sad to say, I recently lost my 80/40m trap dipole. Which is too bad, because it was a good antenna. I used this antenna from four different locations in Georgia: Gwinnett, Floyd, Walton and Fulton counties. I made thousands of contacts on this antenna. It had been the first antenna I put up at Floyd and Walton counties, and the only antenna at Fulton county.

It was last up at the parsonage in Fulton county. Apparently a group of teens was doing some volunteer work near the parsonage. They saw the rope tied off to the parsonage fence and thought it was something other than it was, so they untied it.

After this, half the antenna fell down to the ground and was left there. When the landscapers came by to mow the grass, they ran over it....

So, about 80 feet of rope, insulator and one of the traps was completely destroyed. The other half of the dipole is still intact, up in the trees. But most of one element is gone -- clearly the landscapers threw it away.

Plan is to design an 80/40/20m trap dipole, using traps made with coils and capacitors, since they have much higher Q than the coax cable traps. I'll also place the traps on frequencies well off the operating frequency.

Uh Oh. Not Good.

Well, if it isn't one thing, it's another. After celebrating getting the A3S/A743 rotating again, I've found a problem. The SWR shifts I mentioned? On a dark night, I went outside and looked up at the antenna while WSJT-X was transmitting on FT8 trying to contact someone. I tried this on 40 and 20m.

I observed one of the 20m traps on the driven element light up with arcing using 100 watts. It was visible in the drain holes and end caps of the trap.

At the very least, I'll need to take the driven element down and rebuild it.

Update: I've tried this experiment on 15m, and I see no SWR shifts even using 500 watts. I think the problem may be confined to the 20m trap(s).

Rotating Again!

Well, it didn't take months after all. As I wrote last month, my A3S/A743 had been stationary since December. But with the beautiful spring weather here in Georgia, I managed to get to the top of the tower and finish the installation.

It's now rotating freely, as expected. It's really good to be able to use the beam as intended, and not have it fixed roughly east.

I do wonder if the A3S/A743 needs repair, however. I'm still seeing occasional SWR shifts at 100 watts on 40 and 20m. I'll need a gin pole to take the antenna down to refurbish.

Back on the Tower Again

During my December vacation, I started a rather ambitious project on the tower. Since its installation, my A3S/A743 has been about eight inches from the very top of the mast. My intent was to put the beam at the very top of the mast, in order to give more room to stack an A50-3 under it.

It had been a while since I climbed on the tower, and any work at the very top is always nerve-wracking. As I've written before, sometimes you get up there and decide you've had enough.

Anyway, back to the December project. I conscripted my daughter Lauren to be my ground crew. I ascended the tower, removed the rotator and hung it from a couple of nylon loops off the side of the tower. Then I lowered the mast into the tower, until the A3S/A743 bracket was right at the top of the tower. The mast and antenna are somewhat heavy, weighing about 50 lbs. I relied on a pulley at the top and bottom of the tower and a haul rope to get support from my ground crew.

The tricky part of this operation was going to be moving the antenna higher on the mast. I had two options. First, I could loosen the bracket U-bolts, lift the antenna higher, then retighten. This would only take me about five hands, and I was only born with two. Second, I could loosen the bracket U-bolts, then lower the mast into the tower. While this seems easier, I had visions of the mast going too low and the antenna falling off the tower. Plus, I was afraid that we'd drop the mast and it would fall some 40-some feet into the base of the tower. And then the antenna would fall off the tower.

Plus, my daughter was having a lot of trouble getting sufficient leverage on my pull rope, which was 1/4". After being at the top of the tower a little over and hour, I decided to continue the project later.

Little did I know that it would take two months before I could get back up there!

In the intervening time, I had purchased 120 feet of 9/16" braided black poly rope. Our first order of business was to replace the existing 1/4" rope with this much more substantial lanyard. Once again with my trusty ground crew, we set out to complete the project.

With the bigger haul rope installed, I surveyed the top of the mast. I had thought that perhaps the antenna had slid down the mast in the 18 years it has been up. But a close examination of the mast showed no evidence of that. It had always been at that level.

Standing there 40-some odd feet in the air, 20 feet above the edge of my roof, I wondered if loosening the antenna would get me into a whole new world of problems. I decided at that moment I wasn't going to mount the A50-3 under the larger beam. What we needed to do was hoist the mast back and up and put the rotator back in place.

This proved to be a problem. Despite all her hauling away on the rope, Lauren was unable to raise the mast any significant distance. It was only with me grabbing the mast with two hands and pushing we were able to move it at all. I ended up locking down the mast with a couple of bolts in the tower and climbing down to solve the problem.

I had a ratcheting come-along, but hauling it up and using it on the tower was problematic. I ended up tying the come-along to a support pole, then hooking it into the haul rope via a tied loop. This would allow Lauren to use the come-along to provide lift, and I could manage things at the top of the tower.

After climbing back up, things moved a little more quickly. The come-along provided plenty of tension, but I found that I had to move the mast with my hands to get it to budge -- there's just too much friction and too much stretch in the poly rope. In a few minutes, we had the mast nearly back up into position. I had to re-position the pulley to get the last few inches to make room for the rotator.

With the mast locked down again, I hauled the rotator back into position. Thereupon I discovered two problems. First, one of the four nuts on the U-bolt that clamps the rotator to the mast was missing. In the two months on the tower, it apparently shook loose and fell off. Second, the rotator connection at the base of the rotator were loose -- one of the forked lugs had fallen off the wire and would need to be replaced.

Not having the necessary hardware at the top of the tower, I finished as much of the assembly as I could and came down the tower knowing that this project would be finished on another day. Hopefully, it won't take a couple of months to get back up there.

Ameritron AL-80A - Fixed!

AL-80A re-assembled, needing just 3-500Z and cover.

As I wrote previously, my AL-80A needed a repair. The plate choke was burned, with several windings melted, the protective diode and capacitor on the B- rail to ground had gone open, and I'd found that the amp would not tune on 160m -- due to some melted switch contacts.

I thought it might be a while before I could get around to doing this -- considering the last repair took about a year. However, since I had some parts on hand, I put the amplifier on the bench and got started.

1N5308 diode next to glitch
resistor on rectifier board. And
the replaced capacitor below.

First order of business was to fix the protective circuits on the B- rail. I removed the 1N4007 I had installed earlier. I tested it and found it to be completely open. Which is pretty much what I expected, given that the capacitor had opened destructively....

I replaced the capacitor with a fresh part, and installed a 1N5308 diode, as recommended by W8JI. And I mounted it on top of the board this time.

Next part to arrive was the Ameritron Plate Choke (Part Number 10-15197). It was a thing of beauty, and despite the package having a nice accordion dent in one corner, was intact.

Replacing the choke was actually pretty easy. I figured out I had to unsolder the wire to the parasitic suppressor and plate cap connector, and then the two blocking capacitors. This was much easier with the tube removed. (I put the tube inside the plate choke's packing box). I then removed the mounting screw and unsoldered the high voltage and the bypass cap.

Beautiful new choke installed.

Oh! Did I mention that you need to unplug the amplifier and make sure the plate circuit is completely discharged before sticking your hands into the amplifier? No? Gosh, that would be dumb. Of course, you do that first.

The old choke had a teflon washer under the ceramic, but it completely disintegrated when I removed the choke. I decided it wasn't required, and mounted the new choke directly to the sheet metal base.

The new choke had a slightly different geometry with respect to the lugs at the base and top. I decided to loosen the lug on the top and rotate it about 100 degrees. Otherwise, the blocking caps were not going to reach. To move the lug, I first had to unwind the top end of the winding and re-wind it to the lug. I think the choke wire ends were unsoldered for this reason.

Once in position, the lugs were easy to solder.

The final task replaces the melted switch contacts. I must say I got a lot of positive answers from the Amps email reflector (amps@contesting.com). Their diagnosis of my issues was spot on, and I got a lot of helpful advice.

Vic Rosenthal 4X6GP sent a link to an article about band-switch arcing on the Heathkit SB-1000, which essentially was a clone of the AL-80A. He suggested I should add the corona washer, which would help prevent more melted switch contacts. From what I can tell, my AL-80A is a very early model, and it did not have this modification. George Hall N2CG also sent me an email with pictures of the washer.

A huge thank you to goes to Louis Parascondolas, who not only wrote to me with suggestions on how to replace the switch contacts, but mailed me six contact elements (I needed four), plus the brass 2-56 hardware needed to secure them. Thank you, Louis!

Switch wafers disassembled. This was the hard part.
On left is the wafer where the contacts were replaced,
shown with contacts removed, and glued.

Replacing a switch contact isn't a huge deal. The first step is to remove the switch wafer. That took some doing. I deduced I could accomplish this without doing a lot of desoldering and re-wiring. The rear bandswitch wafer is basically connected to the coils and a couple of padding capacitors. One end of each coil was fastened to the capacitor studs, which simply required removing a couple of nuts. The larger coil had two small phillips screws holding it to plastic mounting blocks. The padder capacitors could also be unscrewed from their lugs. Easy right?

Not so fast! a single wire needed to be unsoldered connecting to the loading cap, and the rear switch wafer slid off with both coils attached.

The second wafer just had three connections, easily desoldered: coax and coil end, coil tap, and the cap. Once those were removed, it slid off.

The third wafer is the one we are after. I unscrewed the connection to the plate padder cap, and slid it off with the coax connection in place. That made it easier to unsolder the coax.

Once you get these wafers off, you have to handle them very gingerly! They are delicate ceramic and can easily shatter. The tricky part is to remove the old contacts. I recommend a drill press and very small drill bits to drill out the rivets holding the contacts in place. Gradually go to larger bits until you have removed all of the rivet material. Go very slowly because you don't want to break the ceramic switch wafer.

This is what I told myself, and I managed to get the contacts off with no trouble. I still had the shell of the rivet, which I carefully drilled out of the first hole. The last hole, of course, was a problem. I broke the switch wafer.

New switch contacts engaged for 160m.

I apparently said something aloud which brought my younger daughter into the basement to see if I was OK. (I was) The wafer was now in three pieces. What to do? I decided that I could glue the three pieces together, and it should hold. Superglue to the rescue! The glue took easily to the ceramic, and soon I couldn't tell where the split was.

I cleaned as much of the burnt contact debris off the two switch wafers as I could. When I was done, you could not see any discoloration of the L network (second) wafer, but there was still a little in the contact well of the 160m padder (third) wafer. The contacted would cover that up.

Adding the four contacts to the switch wafer was really easy.

Getting all the switch wafers re-assembled was the hard bit. I added the coax ground connection to the 160m padder (third) wafer, but I held off on the padder capacitor connection until the very end, so I could place the corona washer.

The L network (second) wafer was a bit problematic. I couldn't remember the orientation of the switching portion of this wafer, as there are two ways to put it on. Then I couldn't remember which wires went where. More pictures before disassembly would have been helpful. Studying the schematic made it clear which way things went.

Corona washer in place.

The bandswitch (first) wafer was easier. The tricky bit was soldering the connections to the loading capacitor.

Last bit was to install the corona washer to the padder cap. A brass washer was specified, but I didn't have one in the junk box. I made do with a steel washer and a lot of solder. I verified the continuity of the connection with an ohmmeter. Perhaps I'll redo this the next time I have to fix the amp. (which I hope may be a while)

After any fix like this, there's always the moment of truth. No sparks turning it on, and a quick test on a dummy load proved it tuned up with no surprises on 160, 80, 40, 20, 15, 10, 12, and 17m.

Ten minutes later, I had replaced all 13 cover screws and was already using the amp to chase DX on 40, 20 and 17m.

Working great again!