Monday, June 4, 2018

Cushcraft A50-3S

A50-3S standing ready.
A year ago I found a deal on a used Cushcraft A50-3S. I managed to scoop up this barely-used antenna for $80. It was missing the mast U-bolts, which set me back about $10 from Cushcraft. For less than $100, I had a functional 6m beam, which languished in my basement for way too many months.

I fixed that problem the past weekend. I got the 6m beam outside, put it on a mast and checked the SWR. My dimensions came out perfect, as the SWR curves were exactly where they were supposed to be.

The mast was something I had lying around. It originally supported a Butternut HF-4B beam and a long 17-element F9FT 2m beam. That was a long time ago - about 25 years.

The mast consists of two 10 foot sections of EMT. I would normally not recommend using EMT as a mast material. It's not a structural support, and the metal alloy is fairly ductile, as it is meant for bending. For really light-duty service, it can be adequate.

Sawhorses make for quick tune check
I don't remember the exact sizes of the tubes. I think the bottom tube is 1 1/2" EMT, and the top is 1 1/4" EMT. The top tube slides easily into the larger bottom tube. A 1/4" bolt about 12" from the top of the larger tube supports the smaller tube, giving an overall length just shy of 19 feet. An EMT coupler with some long bolts keeps the smaller tube firmly against the wall of the larger tube.

With the mast across the sawhorses, and the reflector just off the ground, the antenna is easily checked for tuning.

With that done, I just needed a way to hold the mast vertical. I already had an eight foot mast in the yard that used to hold the Cushcraft R7000. With a couple of short pieces of rope, the 19 foot mast was lashed to the eight foot mast. And, voila!

The lashings hold the mast firmly, but it can be rotated by hand. (aka Armstrong rotation) It may only be temporary for now, but it works quite well. I put many 6m stations in my log this weekend on FT8. It's good to have a real 6m antenna!

Monday, May 28, 2018

WinKeyer 3 Serial

The finished product.
What's the use of having an excellent soldering station like the Hakko FK-888D if you don't have something to build?

I recently splurged about $40 and bought a WinKeyer 3 Serial. This is a very nice little board that has a WinKeyer 3 chip powered solely by the RS-232 signals on the serial port. I figured this would end all the timing problems I have with keying the rig from a serial port RTS line.

I would have preferred to buy the similar WinKeyer USB Lite, but unfortunately, that product has been discontinued. I suspect it may be because the Lite cut into the sales of the more expensive WKUSB-SMT.

The WK3 Serial Kit.
The kit arrived in a little plastic pouch. There's no manual, but there's a little slip of paper with a URL to download a manual. Not a problem. I just parked one of my computers on the workbench to read the instructions.

Assembly went quickly. I actually ended up following the steps out of order. I guess I should pay better attention, as the first part I assembled was the IC socket. I skipped assembling the resistors and diodes. Oops.

I quickly realized my error and went back and assembled all those parts. This is not a Heathkit. It's more like "insert all the resistors, solder, insert all the diodes, solder, insert all the capacitors, solder" type of kit.

Flip side of the kit. Not
many parts in this one.
For me, this was a piece of cake. Given how simple this kit is, it wouldn't be hard for a much less experienced kit builder. I elected not use use the speed potentiometer at the moment.

Once assembled, testing is a matter of hooking it up to a Windows machine and using a test application.

K1EL provides two programs: WKtest and WK3demo. The WK3 Serial Kit manual has a link to WKtest, although this appears to be an older application. WK3demo is the preferred application to use, at least according to the web site. I tried both, and they both worked.

This kit fired up and worked right after assembly, so no troubleshooting was necessary. I could easily program CW text to flash the on-board LED. Perhaps the hardest issue I had was figuring out exactly which USB Serial device I had hooked it up to.

Now that it's assembled and tested, I'll need to find a suitable box to mount it in, and wire up connectors to hook it to the rig. I didn't manage to complete this before the WPX CW contest, so perhaps next time.

Saturday, May 19, 2018

Eliminating the Middle Man

When I first started taking Martial Arts over ten years ago, I weighed 252 pounds. I recently weighed 226 pounds. Perhaps not a huge difference -- especially since most of that weight was lost in the first six months.

That's not to say I haven't experienced any changes from my training the last several years. Far from it. I continue to trade fat for muscle, even if my weight is virtually unchanged. When I look at myself in the mirror in the morning, I don't see the fat guy I used to be.

Indeed. From about four inches above my waist up, or eight inches below my waist down, I actually look kind of skinny.

It's that one foot in the middle that's trouble. That's the fat guy still hanging on. Eliminating him is going to take a lot more work.

Wednesday, February 21, 2018

Hakko FK-888D

Hakko FX-888D standing ready on the corner of the workbench.
If you're going to build something, you need a soldering iron.

My original soldering iron was a crappy Radio Shack unit that got way too hot and burned tips up on a regular basis. I hated it.

At some point, I upgraded to a Weller WP-25 soldering iron. I'm not certain when I bought it. It's been at least 30 years, perhaps 40 years. I can't remember if I used it to build my SWTPc 6800 computer system in 1977 (and that's another story). But it did a fine job putting together the venerable Elecraft K2/100.

The ancient WP-25, still going strong.
While the Weller WP-25 has gotten long in the tooth, it keeps on going. A couple of decades ago, I dropped it and cracked the black plastic hand guard. It has since been held together with electrical tape. I have purchased two soldering iron holders for it, and worn one out completely. Despite the age and abuse, the iron still works quite well. Plus, I have enough replacement tips for a lifetime. I think I'm on my second or third -- they last forever.

So, how did I end up with the Hakko FK-888D? Dumb luck.

Every year, I share a Christmas list with my extended family. This year, I decided I'd like a soldering station, but not something too expensive. I found that the Hakko FK-888D could easily be had for less than $100. So, I put it on my list.

Lo and behold, my Dad purchased one for Christmas.

While I can't say I'm thrilled with the bright blue and yellow colors, the unit does sit well on the desk. The soldering pencil is slim, but it goes easily into the holder. The holder has both a scraping wire and a sponge -- great tools for maintaining a clean tip.

The station unit sits rather tall, but is so heavy there's no danger of it falling over. It's virtually all metal transformer inside. The user interface is a bit awkward: Three 7-segment LEDs and two buttons are it. You'll have to run back to the manual to figure out how to configure anything.

First turning it on, I was surprised at how fast it warmed up. The old Weller took at least 3-5 minutes before it was ready. The Hakko was ready to solder in less than a minute!

The default temperature is 750 degrees F. I backed this off a bit to 700 degrees F. That's plenty hot enough to melt solder.

I've only used this iron a little bit, but I'm amazed at how well it works. It heats up the work quickly, melting the solder soon after application, even on junctions with large terminals or lots of wires. I used it to desolder an old piece of equipment, and the job went very quickly.

I'm looking forward to building something with the Hakko. I think I'm going to like it.

Monday, February 5, 2018

The Venerable Elecraft K2/100

Elecraft K2/100 with KAT100 tuner, as it sits on the desk.

I cannot believe it has been fifteen years since I built the Elecraft K2/100!

When I first got interested in amateur radio, in the mid-70s, I wanted to build my own rig. While I studied for my novice, an elmer of mine insisted that each ham should build his own transmitter. He gave me some parts, and I made an honest attempt, but the "Novice" Transmitter didn't actually work until many years later.

Later, while preparing for college, I tried building a QRP transceiver I might use in the dorm. I built a 7 MHz FET VFO, a direct-conversion receiver, a 3 watt transmitter, and a even a KOX or Key-Operated Switch to do semi-break-in with side-tone and an relative power and S-meter.

This design never did work. Never heard a peep out of the receiver. While the transmitter produced a couple of watts output, it couldn't decide if those watts were on 7 MHz or 14 MHz. The key mistake I made in my youth was building the entire project before testing anything. The VFO worked, the KOX worked, but that was about it.

I had tried to build my own designs, without a lot of success.

I noted the Elecraft K2 introduction in 1999 with interest, but I wasn't excited. While relatively inexpensive, it only produced 10 watts output. I needed a replacement for the venerable Kenwood TS-430S, and that meant 100 watts output. When Elecraft announced a 100 watt PA for the K2 later in the year, I was hooked. Best of all, I could buy the rig in installments, adding options over time.

I joined the Elecraft mailing list, and read everything I could about this great little rig. Sold! On March 1, 2002, I placed an order for a plain Elecraft K2/10 and would receive Serial Number 2548.

On arrival, I spent and hour or two each night building. This wasn't something you could knock together in a couple of evenings. I wanted to do a good job as well, to savor the process, instead of just slap it together. In total, the basic K2 took me nearly 30 hours to build.

Wayne Burdick (one of the Elecraft founders) at some point asked me for any building notes or comments on the K2. This gives you an idea of how grassroots a company like Elecraft is. I sent him a series of four notes with my impressions and some detailed comments. I don't know if he actually used this material to improve the K2 assembly manual, but it's a nice thought.

The K2 is no Heathkit. A real Heathkit would have more drawings and diagrams at each stage of assembly. But, hey, Heathkit is out of business and Elecraft is not.

Any K2 builder can spin yarns about the joys of winding toroids. There are dozens of them in the K2. Frankly, I didn't have that much trouble winding toroids. Tinning the toroid leads, on the other hand, was a real pain. Especially when I didn't tin them up quite far enough and had to do it over.

After 20 hours of construction, I did the Alignment and Test II section and was listening to 40m signals coming through the receiver. Given my previous experience, this was very exciting. You have such a feeling of accomplishment when something you built actually operates.

For the most part, the K2 worked flawlessly after construction. I did have a problem with flaky AGC action, which was fixed with a resistor substitution and a replaced transistor. I also had an intermittent INFO 080 (the dreaded AUXBUS failure) which was caused by a bit of waxy burnt flux between two pins on the control board. The Elecraft mailing list and support email address gave me the information I needed to diagnose these problems.

With the basic K2 built, I started ordering and building options. The KSB2, the SSB module, was up first. The KSB2 has the densest board of all the K2 kits, making it the hardest to assemble. And the FT23-43 cores were so tiny, I originally thought they were fiber washers.

After the KSB2 came the KAF2. I had read enough to know that the K2 audio had an unpleasant hiss that was knocked out by the KAF2 audio filter. Beyond that, however I never found the audio filter to be that useful. While the KAF2 also has a real-time clock, I never found much use for it.

Next was the KNB2, the noise blanker. Having used the one on my Kenwood TS-430S, I felt that a noise blanker would be a required option. But the KNB2 isn't terribly effective at eliminating the noise sources I most often encountered. I was able to determine it was working, and later managed to make modifications to improve it's effectiveness.

The last option for the basic K2 I built was the K160RX -- which has to be the simplest option board I've built. Once installed, I had a very functional K2, with 160-10m coverage, CW, SSB, Noise Blanker, Audio filter. All I needed was to wait for the KPA100 option.

And, indeed, as soon as it was available to order, I placed my order the same day. And then I waited.

Fate intervened, however. While I was waiting for the KPA100 to ship, I was laid off from my job. This was the summer of 2002. The internet bubble had burst, and there were several shocks to the economy, what with the 9/11 tragedy, and the Enron and Adelphia Cable financial scandals.

Without employment, spending hundreds on the KPA100 didn't seem wise and I cancelled my order. I feared I might need to sell my K2. It took me nearly four months to find a new job, as the market was really tight. But as soon as I had a new position in hand, I re-placed my KPA100 order.

I had some trepidations about the KPA100, but it went together pretty easily, and it worked like a charm right from the start.

At this point, the K2/100 became my main rig. With computer control -- something that I had coveted for years -- contest band changes became much easier. I loved it.

Close up of the friendly face of the K2. 
Once built, for a few years I was regularly tearing into it to make modifications. The improved 2nd XFIL mod, the KI6WX improved CW filter rejection mods, alternative AF gain control. The massive A-to-B upgrade. The BFO temperature stability mod. Redoing all of the crystals with the K2KSB2XTALS mod. The KSB2 firmware update to v1.08. The PLL temperature compensation mod. The KPA100 Rev B upgrade with upgraded shield. K2 firmware update to v2.04. K2 Keying modification. The QSK improvement modification. KPA100 current consumption mod. The power control mod.

During these first few years, I also added the KAT100, the KDSP2 and my favorite, the Finger Dimple. The KAT100 really made the rig more versatile. The KDSP2 helped out on SSB with some needed bandwidth filtering, and the auto-notch filter. But the Finger Dimple made tuning the rig a much more comfortable proposition.

From Mid-2005 until 2010, K2/100 served as my main rig without any modifications. 2010 brought a flurry of final mods. The VCO Shielding mod. The KPA100 Rev D upgrade. The KNB2 response and threshold sensitivity mods.

Once I finished all this, I bought the Rework Eliminators kit -- that enables one to swap out option modules without making changes. I don't believe I've used them.

Although the K3/100 replaced the K2/100 as my main rig, I still use the K2 regularly. It is pleasant to listen to and quite capable. The K2 has earned an honorable place on my operating desk, and deserves to be called a venerable rig.

Wednesday, December 13, 2017

Brake Delay for Ham-M and Ham-II Control Boxes

A $30 hamfest find - CDE Ham-II rotator control box.
Proudly installed in the operating position.
When I put up my tower in 2001, I'd had read enough on the TowerTalk mailing list over the years to know about the importance of brake delay. This allows the rotating parts on the tower to coast to a complete stop before the brake wedge on the CDE rotator design engages. Without it, the rotator comes to a sudden and abrupt stop, causing a lot of torsional stress and making the antenna and tower elements wave around unnecessarily. That repeated stress could end up causing failures over time.

The original Ham-M design has no delay. Pushing the lever a little bit illuminates the meter and shows the position indication on the meter. A little more turns the rotator. The moment you stop pushing far enough to turn, the brake solenoid releases and engages on the rotator shell -- causing the sudden stop.

The original design schematic, sketched out in 2001.
Back in 2001, I came up with a very simple circuit. I had some Allied Controls 12 volt relays with a 1000 ohm coil. I figured I could rectify some of the AC from the motor terminals with a big enough capacitor to power the relay for a few seconds. I ended up drawing the circuit to the left.

50 volt PIV rectifiers might not be quite enough, so I wrote 100 v PIV on the design. I ended up using 1N4003 rectifiers which are 200 volt PIV.

I estimated 10 mA of current is necessary to keep the relay closed. Since the left and right motor connections are about 30 volts AC, rectified this would be about 42 volts. Putting a 2.2 K ohm resistor in series drops the voltage down to something less than 15 volts across the relay. All that remained was choosing the right sized capacitor. I had some 1000 uF low-profile capacitors in my junk box, so that was perfect, right? The RC value was around 3, so I expected a delay around  three to four seconds.

Imagine my shock when I actually built the thing and found it took something closer to fifteen seconds for the relay to open! Clearly, a lot less than the full 10 mA was necessary to hold the closed relay closed. I ended up modifying the circuit by placing a 1 K ohm resistor in parallel with the relay. This resulted in a delay closer to six seconds, which was just fine. The relay contacts are wired across the switch contacts for the solenoid, so the solenoid remains activated until the relay opens.
Relay board shoehorned in control box.

I built the circuit on a tiny piece of perfboard just a little bit bigger than the relay. Biggest problem was shoehorning it into the very crowded Ham-M control box.  I figured I could mount it on a right-angle bracket just behind the meter.

Wiring it into the circuit was harder. Assembled, the switch contacts of the Ham-M are inaccessible. I had to remove two sheet metal screws holding the meter panel to the base. That gave me access to the switch. After soldering up the leads, the meter panel goes back in place.

This circuit has been in use since 2001, and has worked great.

At a recent hamfest, I found a deal: a relatively pristine Ham-II control box for only $30. I bought it, brought it home and immediately determined it worked great. It would take the place of the Ham-M control box -- but it needed a brake delay.

The Ham-II design has three buttons. The center button supplies power to the brake solenoid and must be pressed for any power to reach the motor windings. Proper technique would have you press the center button and hold it, then engage the left or right button, holding until the antenna had moved to where you want it, releasing the left or right button, while continuing to hold the brake in with the center button.

Ham-II control box with brake delay installed.
However, if you just pop off the buttons, the brake wedge would slam into the rotator shell.... Not what we want.

It wasn't hard to find the same parts in the junk box. Another scrap of perfboard, a few minutes of soldering, and the same circuit was again created. Mounting in the Ham-II box is a much easier exercise, since there's plenty of empty space. Because four of the connections are to the switches, I elected to mount the board on the bottom of the box, just behind the switches. A threaded standoff was used on an existing screw to hold the board slightly above the switch contacts. The standoff also supplies the ground connection.

This circuit works great. In the Ham-M, the meter and lights would go off once the relay disengages. In the Ham-II, the meter and lights are on any time the box is turned on. It might be nice to have an indicator that the brake is engaged. Perhaps this will be a future addition.

Friday, November 24, 2017

Forty Years of Personal Computing - First Steps

As my present for Christmas of 1974, my older brother gave me a one year subscription to 73 Magazine, starting with the January 1975 issue. This was pure genius on his part. He knew I was showing an interest in amateur radio, plus he would have the opportunity to read my copies, so he didn't need to continue his own subscription. I enjoyed the magazine so much, I continued my subscription until the magazine's demise in 2003.

1975 an exciting time in the world of the electronic hobbyist. MITS introduced the Altair 8800 in November of 1974, and other vendors soon jumped into the market. Microprocessors and related components were coming available, and 73 Magazine was writing all about it.

With the February 1976 edition, 73 Magazine added a special section called I/O, to talk about the developments with these Microprocessors. To my teenage mind, I just had to have one of these machines. They were expensive, but I slowly saved my money from my paper route.

By the spring of 1977, I fell prey to a surplus equipment advertisement from Verada 214. The ad promised a complete system with a keyboard, display, microprocessor and dual cassette decks -- the Viatron 2111 -- only $699! It seemed like a perfect way to enter into the budding world of microprocessors without spending a fortune. Although the equipment arrived as advertised, there was no microprocessor to be found -- nor any way to program the device. After studying it thoroughly for a week, I decided the purchase was a mistake. My father managed to convince the company to refund my purchase price for the cost of shipping it back.

My father could see the seriousness of my interest, so he signed me up for a summer course at the local college where he worked. This was a six week course, and the first three weeks were spent on learning about VCR and other television technology. (It really is too bad that Quasar Alpha-wrap video cassettes didn't catch on -- but they were HUGE) But the last three weeks included plenty of hands-on time with a KIM-1, the 6502-powered single-board computer. Forty years later, I can't remember what programs I wrote, but I thoroughly enjoyed that first taste of programming.

About this time, a computer shop had opened up in Morgantown, WV, about 20 miles away from my home. My parents took me there a few times. I was fascinated to see the MITS and IMSAI equipment I had read so much about over the last couple of years. But the prices were beyond my reach. These systems cost upwards of $2000, much more than I had to spend. I'd have to wait for something more affordable.