Saturday, January 31, 2009

My Novice Story

Seeing a link to the Novice Historical Society, I thought I would write my own Novice Story.

My start in radio was pretty conventional. If you have ever read So You Want To Be A Ham, the conventional entry in amateur radio comes after being a short-wave listener (SWL). You encounter other hams talking on the air, and eventually discover you can do more than just listen. Up until the widespread adoption of SSB, this was perhaps the most popular technique for discovering amateur radio.

I got started through my brother Ben (now NJ8J). Ben is five years older than I, and my mother always joked that I wanted to do everything he did. (And she was surprised when I often could) Christmas 1969 found us with our grandparents, and my Uncle Frank didn't know what to give us boys. He ended up getting Ben a Radio Shack Science Fair Globe Patrol receiver. This was a three transistor regenerative receiver, with AM broadcast and short wave bands. Frank, Ben and Dad built it, and my Grandfather had to step in and troubleshoot it (one reverse connected diode was enough to keep it from working).

Unfortunately for Frank, that was to be his last Christmas, he die tragically in April 1970, just short of age 25. But that little radio started something for both of us. Next Christmas, our parents bought us each Heathkit short-wave radios. Ben received a GR-64, and I a GR-81. We quickly became avid radio listeners.

The GR-81 wasn't that great on short-wave, so I initially concentrated a lot of AM broadcast DXing. (Best DX was WOAI in San Antonio, TX from Fairmont, WV) Ben took to listening to more short-wave broadcast, and he quickly found the ham bands as well. Ben had learned morse code in scouts, so he was "reading the mail" on the CW bands as well.

I had tried to learn morse, and about age 14, I had convinced myself that I was just one of those people who were incapable of mastering it. Then something amazing happened. Ben got his Novice license in February 1975. Of course, I always had to do everything he did, so naturally, I started to learn the code again. I bought and built a Heathkit HR-10B, and I began to practice by listening to W1AW and the Novice bands. By November 1975, I passed my Novice license, and was WN8WOY.

Getting licensed was one trick, actually getting on the air was another. By this time, I had realised that the HR-10B was not a great receiver for CW work -- the IF response was just too wide. Using money from my paper route, I bought a used Heathkit SB-301. The difference between the two receivers was amazing. You really could listen to just one signal -- especially after I bought the 400 Hz CW crystal filter.

The SB-301 kinda broke my budget for a few months, so it wasn't until June 1976 that I could afford a transmitter, in the form of a used Heathkit SB-401. Thus, I had the matching pair of Heathkit SB-series twins. Novices were no longer limited to crystal control, so the SB-401 wasn't a bad choice.

One problem being a Novice in those days -- you were limited to 75 watts power input to the final amplifier. The SB-401 could do about 180 watts, so I removed one tube and operated that way. During that summer, the FCC changed the rules to allow Novices up to 200 watts PEP output. Of course, I didn't find out about this until the fall. The FCC also decide to drop the distinctive Novice callsigns, so in the fall of 1976, I was now WB8WOY.

The summer of 1976, I did a fair amount of operating -- a handful of contacts every day. Mostly 40m, some 80m, and a few 15m. My antenna at first was a 40m inverted-V that was mounted on standoffs just underneath the eves of the house. The ends were within about a couple of feet of the ground, so this antenna really didn't work well. I also build a small L-network tuner for the long-wire I used for SWLing for use on 80m. It didn't work well, either. 

The Novice bands in the 1970s and even 80s were very different from today. Today, most evenings you could tune the CW bands and fail to hear more than a few CW QSOs, and none of them at slow speed. (Of course, if there's a contest or DXpedition active on a weekend, you'll hear lots of activity) Then, the Novice bands were a hotbed of activity, with slow speed QSOs going on all the time, every day.

In a year and a half on the air, before my Novice license expired, I made about 210 QSOs. That experience made a lasting impression on me. When I got my General class license in the summer of 1979, I often found myself operating in the Novice bands. 

Sunday, January 25, 2009

Three Safety Rules for Tower Work

For myself, I've adopted three rules in order to ensure the safe execution of all tower work. But, before I write about the rules, I first have to tell a sad story.

When I moved to my current QTH, there was a fellow ham nearby -- he lived less than a mile from me. Though he lived in the neighborhood near me, I never met him. I believe his name was Paul.

Paul had a modest tower and tribander, like me. At a hamfest in November, a fellow ham loaned him an MFJ antenna analyzer. Paul was quite eager to climb up and make some fine adjustments to his antennas. He asked his friend if he would come over, but it was a cool, slightly drizzly day, and his friend suggested he do it at another time. Paul couldn't wait.

So, he climbed the tower himself that day. When his wife and kids came home from shopping about three hours later, they found him at the base of the tower. Unfortunately, it was too late.

Near as anyone can figure, he tried to climb while holding the analyzer with one hand, so it wouldn't be damaged. Somewhere on the way up, he lost his grip with his other hand. Ironically, he had full safety harness, but with one hand occupied, it was too difficult to clip in to the tower.

Tower climbing is a dangerous business. I knew of Paul's accident when I built my tower, so, for myself, I made three rules:
  1. Never Climb Alone.
  2. Never Climb Except in Good Conditions.
  3. Always Take All Safety Precautions.
I borrowed the first rule from SCUBA diving. SCUBA divers know never to dive alone. Tower climbers should never climb unless they have at least a ground crew. If nothing else, a ground person can call 911 should anything bad happen. I've taught my kids from an early age how to properly act as ground crew. If nothing else, if I should fall and be hanging from the safety lanyard, I know someone will call 911 and get the emergency crews out there. I wouldn't want to be hanging there for hours until someone notices.

The second rule is pretty broad. Good conditions include the weather. I refuse to climb in rain, snow, windy, dark, or really hot or really cold conditions. Good conditions also apply to the climber. Tower work is demanding, physically exhausting. I refuse to climb when I'm tired, under the weather, or just not mentally "with it". 

The third rule should be common sense. I climb with a full safety harness. I have a fall arrest lanyard clipped into the D-ring on my back, and it is always clipped into the tower. When I'm moving the fall arrest, I have a short 3-ft rope lanyard from the D-ring to the tower. I also always use my positioning lanyard during the climb. It allows me to stop and rest at any level. 

All these precautions slow me down. I have some friends who like to free climb to the top, then they belt in. That's their prerogative -- but it's not for me. I'd rather be slow and safe than fast and sorry.

So, there you have it. Enjoy your tower, plan your climb, execute your plan, and stay safe.

Saturday, January 17, 2009

The Little Receiver That Could

A couple of years ago, when I build my "Novice" transmitter for Straight Key Night, I figured I had to have a receiver to go with it. I used my K2/100 as the receiver in 2007 and 2008, and nearly fried my K2/100 that second time when I accidentally hooked up the transmitter into the K2 instead of the antenna.  (The K2/100 front end is really tough! It survived about 12 watts of CW for about two or three minutes)

The transmitter was built using techniques typical of the early 1960's -- all tubes, except the power supply used silicon rectifiers. I figured that the companion receiver ought to be all solid-state. And not just all solid-state -- but using nothing but integrated circuits.

Well, I'm pleased to say that I almost achieved this goal. The receiver uses one transistor, but we'll get to that in a moment.

I took my design inspiration from the Norcal Sierra, as published in the 2000 ARRL Handbook. The receiver in the Sierra uses the common NE602 Mixer / Oscillator and the MC1350 IF amplifier. An LM386 provides audio amplification.

The NE602 is a very flexible and powerful part. I'm sure the receiver builders of the 50's would have loved to have a component such as this. The oscillator block is stable, and covers a wide frequency range. The mixer is fully balanced, offers some gain, although it's dynamic range leaves something to be desired by modern standards. 

The MC1350 is practically an entire IF strip in one chip. It has lots of gain, and easily applied gain control. 

Perhaps the best advice for building a receiver is to start with the power supply, then proceed to the audio stages, working your way backward to the front end. Which is exactly how I began. Power comes from a 12 volt supply, but the NE602 can only take 8 volts. An LM7808 would be perfect, except I didn't have any. I did have a bunch of LM7805s, so I used one of those, and boosted the voltage by stacking four 1N4001 rectifiers in the ground lead, giving about 7.5 volts.

Next was the LM386 audio stage-- while really popular, it can be somewhat cantankerous. Initially, it was fine, but as I added stages, it become unstable and would oscillate until I put a 10 ohm resistor and .1 uF cap to ground. 

An NE602 (I used the equivalent SA612A) is the BFO and product detector. At this point, the receiver was working great. Then comes the MC1350 IF stage. it was pretty painless as well, but for some reason, the radio was less sensitive than before. 

Turns out I had a solder blob shorting across the LM386 inputs. I wasted a lot of time figuring that out. 

At this point, I added LM324 for the AGC amplifier. I wanted to use a 8-pin chip, like the others, but all the op amps I had required dual voltages. 

By the time I finished before SKN 2008, the receiver looked as on the right. You can see a four crystal ladder filter, with matching toroids on each end. You can see the schematic evolving as I build. 

At this point, the receiver consists of a 4.915 mHz IF, product detector, amplifier, and audio-derived AGC. The tricky part is the oscillator and first mixer. Another NE602 stage brings the 40m band to the IF. At 7 MHz, the oscillator would be on 11.915 MHz. This had me a little worried. I remember as a Novice trying to build a 7 MHz VFO and having trouble keeping it stable. A few turns around a T50-2 toroid, and the receiver is on frequency and quite stable.

Tuning is accomplished with a 6 pF variable capacitor. This unit has a 8:1 reduction built in, and came out of a Heathkit SW-717. By selecting the right inductance, the oscillator tunes about 150 kHz, which means about 35 kHz per turn.

With the basic circuit going on the workbench, it was time to move everything to a nice-looking package. I had a nice painted aluminum cabinet that was perfect. It's always a bit gut-wrenching to drill into a new cabinet. The hardest part was getting the geometry of the tuning capacitor holes right, so that's where I started. 

The tuning dial is made from a brass bushing and a piece of acrylic. It fastens to the main shaft of the capacitor, the inner shaft connects to the knob. I actually had to make two of these, as the first one didn't have enough clearance to allow for the thickness of the panel.

One item I wanted for the receiver was an S-meter. I found three surplus edge-on meters in the junkbox that looked perfect. I believe they may have been decided for CBs, as the top scale has S-units, the bottom is labelled Tx Power. 

By this time, I had replaced the LM324 with the smaller LM358, but had one unused op amp -- which I used as a voltage follower on the AGC. This op amp drives the meter. 

One last detail was muting the receiver. At this point, I abandoned my restricting on using transistors. A 2N3906 PNP transistor channels 7.5 volts to the AGC input on the MC1350 when it's base is grounded through a 10 K resistor.

Here's a view of the inside. I had to make a few adjustments once I started using the rig. First problem was the AGC time constant was too long. Even with the rig muted, the receiver still responds to very strong signals -- and so acts as a sidetone for the transmitter. But the audio from this drives up the AGC and it would take a while to hear anything when going back to receive. I reduced the 10 M ohm resistor to a 3.3 M ohm, and this seemed to work well enough.

Second problem was the pitch of the audio was a bit high. Adding a bit of capacitance to the BFO oscillator moved the pitch down to around 700 Hz.

The ladder filter provides a modestly narrow response, even with three crystals. Single-signal reception is easy to achieve. Tuning is a little sensitive, but does not require too delicate a touch. Audio response is quite good and very listenable. It's not really microphonic, but if you tap the case roughly, you can hear a small change in frequency. This is likely caused by the long lead to the tuning capacitor.

Rig could still use a bit of refinement. First, it needs a speaker, and could use a stereo headphone jack. Second, I'm still hearing a bit of oscillation on really strong signals, so audio amplifier is probably being over-driven. Third, the frequency dial is currently the back of an old QSL card. This rig deserves something neater. Forth, I'd like to tweak the circuit, perhaps replacing the single-ended choke on the output of the MC1350 with a full toroid transformer stage. Last, the S-meter is a bit sensitive. It tends to go to S9 even on very modest signals. 

Funny how much fun it is to listen to the band with a receiver you've built yourself. I get a real kick out of it.

Friday, January 9, 2009

Putting Up a Tower - Antennas, Etc.

With the tower up in our previous installment, it's now time to add the antennas, feedlines and everything else that makes the tower system work.

A tall tower is a great target for lightning, so every tower system needs a protective ground. Mine has four 10 foot ground rods -- one next to the tower base, and three others fifteen feet away, all tied together with 6 gauge copper wire. 

Getting forty feet of ground rod into the ground might be a lot of work, except I built a special tool. It's a 12" steel pipe nipple with couplers on each end and a plug on one end. fifteen pounds of dumbell weights are added to the other end. Basically, it's a 15 lb sledgehammer that can't miss the end of the ground rod. I've been using this tool for years, and it works really great. 

So long as the soil has a reasonable amount of moisture, you can pound in a ground rod within a foot of the ground in less than five minutes. The last foot is taken care of with an ordinary eight pound sledgehammer. During the drought in the late 1980's, the Georgia red clay was particularly difficult to put ground rods in, but this tool could handle it.

With the ground portion in hand, let's look at preparing the antennas. I purchased a Cushcraft A3S years ago. It's one of the last tribanders designed without computer modeling. It's rugged yet lightweight, and offers reasonable performance. For a small (14 foot boom) tribander, it's probably one of the better designs available. 

It was up at my old QTH for about six years, then in my basement for five years, then up at Mike, W1YM's place while he was waiting for his Butternut Skyhawk for almost two years. At this point, it needed some help. 

I ordered replacement trap end caps from Cushcraft -- all 24 of them. With the end caps off, I blew all the debris out of the traps. I also tightened up all the sheet metal screws which secure the ends of the traps to the elements. I wrapped electrical tape around the driven-element insulator, in order to protect it from the Sun. 

As I re-assembled the elements, I chose to set the beam half-way between the CW and MID settings. I believe this is the best compromise to cover the entire band with a reasonable SWR. I got the idea from the recommendations that Steve, K7LXC made about the Cushcraft 40-2CD.

It's always a good idea to test an antenna on the ground before getting on the tower -- where it will be much harder to make adjustments. This can be done by pointing the antenna skyward with the reflector 3 or 4 feet of the ground. I used my back deck to support my antenna on a short piece of mast lashed to the deck rail.

At this time, I also added the feedline pigtail for the antenna, and the balun. Cushcraft recommends making a coil of coax feedline and taping it to the boom. While this will work, it may not be the best choice. WA2SRQ wrote a posting to the TowerTalk reflector several years ago that showed other balun designs would work much better. 

Originally, I planned to add a piece of 4 inch PVC mounted to the boom with eight turns of coax. However, I happen to stumble on some very large ferrite beads that would fit entirely over RG-213 coax. They appear to be of type 77 or similar material -- excellent for a choke balun. 

So the balun consists of ten of these beads, strung on the coax pigtail, held in position to the coax with wire ties. The coax is suspended below the boom with twisted 12 gauge solid copper wire. 

A quick test with the antenna analyzer showed the antenna SWR curves were right where the should be -- about 50-100 kHz low because of the near effects of the ground. Now it's time to put it on the tower.

Remember, this was my first tower work. While I had done all the climbing to stack the sections, I wasn' t really comfortable with the tippy top of the tower. Once you are 20 feet above the upper bracket, there' s a certain amount of sway thats rather unnerving. Fortunately, my friend Gary K9AY was close by. Gary has much more tower experience than I, and he was kind enough to install the antenna. I was on the haul line for the gin pole, but I did managed to snap this picture as the antenna goes in place. 

With the antenna on the mast, there's still much work to be done. Loosening the mast set screws the gin pole is used to move the bottom of the mast well above the rotator shelf. And then the rotator was installed. Be sure to position the antenna North to match where we left the rotator.

I routed my feedlines an rotator cable up the inside of the tower. This is much harder than just taping it to the outside of the tower, but it prevents complications if you later want to shunt-feed your tower. The cables are held to the tower alternately with electrical tape and twisted 12 gauge wire. The twisted wire is better than a wire tie, because it can be reused. It's also really cheap to salvage bits of wire out of household romex. 

Remember my rotator had a defective motor cap. One really odd thing about the Ham series of rotators is that the cap is in the control box, instead of in the rotator. I opted to place the cap near the rotator by installing it in a small NEMA box that is U-bolted to a tower leg. To allow the rotator to be removed, I used two 4-pin trailer connector sets. These are inexpensive, weatherproof and very rugged. To avoid cross connecting, I used the mostly male and mostly female ends  on each side. The trailer connectors join with the rotator cable inside the NEMA box.

So, in early September, 2001, my tower was fully operational.

Thursday, January 8, 2009

Putting Up a Tower - Erecting the Tower

In our last installment, a solid foundation for the tower had been successfully constructed. The next phase is the erection of the tower itself.

At this point, there's almost 20 feet of tower standing, but 4.5 feet of the bottom section is below the surface of the concrete, so the tower is a little more than 15 feet tall, bracketed at about 9 feet off the ground

In the picture, you can see the remaining tower sections lying on the ground, as well as the Gin pole loaned to me by Dan, W4EA.

Before erecting the tower, I had done some preliminary work. Since this was a used tower, I had fitted all the sections together on the ground to ensure they would mate properly. I also did some work on the top section.

I used the Rohn 25AG3 pointed top section. This section ends in a 2 1/4 inch inside diameter galvanized tube, which can be used to hold a mast. I wanted to make sure the rotator shelf and mast were properly aligned on the ground, so I came up with the following technique.

With the section horizontal, I fitted the mast through the top. I then mounted the rotator to the mast. The rotator is an ancient Ham-M that I found at a hamfest for $50. It needed a bit of cleanup and a new motor cap, but then it worked fine. I then mounted the AS25 rotator shelf first to the rotator, then to the tower and tightened everything down. This ensures all the parts are aligned with each other.

At this point, I used bungee cords to prop up the top section next to the standing sections and wired up the rotator for a test. The mast turned without any binding. I then removed the rotator and mast from the top section, leaving the shelf in place. Rotate to North before removing the rotator.

Before going any further, the next step is to drop the mast into the tower. This will make it much easier to later haul up inside the tower, rather than having to hoist it up and insert it down through the top section. My mast is 9 feet of 2 inch diameter, 1/4 inch aluminum tubing, donated to my project by Gary K9AY. 

Stacking sections is pretty straightforward. Hoist the gin pole near the top of the existing tower, then use the gin pole to hoist the next section in place. Bolt the sections together and repeat.

I planned for brackets at 17 feet and 25.5 feet. The top bracket is just underneath the eaves of the house. After putting the third section on, I mounted the 17 foot bracket. It is tied into the rim joist with lag bolts. This is not an optimal arrangement. The lag bolts could easily pull out of the wood -- but the 17 foot bracket is just there to help stabilize the rest of the tower from flexing, and to act as a backup should the top bracket fail.

These brackets are first mounted to the tower, then bolted to the house. This ensures proper alignment between the two. Just make sure the tower is plumb before drilling into the house.

After the 17 foot bracket was in place, I removed the bracket at the 9 foot level.  The next section is added, and it's time to mount the top bracket. 

The top bracket gets a lot better mounting treatment. I removed part of the siding so I could get directly to the top plate of the wall. I added a 2x4 to make up the missing depth. Fastening the bracket to the tower, I then used the bracket holes as a guide and drilled entirely through the top of the wall. 

Carriage bolts inserted from the inside of the wall through to the outside and secured with nuts. The ends of the bolts inside are hidden under a bit of crown moulding. 

The last section is the top section, with the rotator shelf in place. Once mounted, the gin pole is used to lift the mast to the top, and locked in place with the set-screws in the top section. Tbe tower is ready to receive antennas, so we'll get them ready next time.

Wednesday, January 7, 2009

Putting Up a Tower - Pouring the Foundation

At my last QTH, I had a tribander on a roof tower. The roof tower installation wasn't perfect -- it leaked when it rained hard. I promised myself when I moved to my current QTH 14 years ago, I would put up a real tower. I sold the roof tower and put a vertical out in the yard on an eight foot mast in the meantime.

I didn't realise but it would be seven years before I finally got that tower in the air. I really owe it to my friend Mike, W1YM. He encouraged me to put up the tower, he gave me some radio-related items before he moved to Oregon to sell to help finance the project, and he supplied lots of helpful information. 

During the construction process, I took several pictures using a Casio QV-11 digital camera. This was one of the earliest consumer digital cameras, so the image quality is pretty poor. I apologize in advance for the poor quality of the images.

The process starts with the foundation. Rohn calls for rebar in the foundation, so the first we build the rebar cage. I built mine in the basement using just a piece of stout pipe to do the bending. Here's a photo of the completed product.

To keep the cage from skewing, I added some pieces of steel wire across the face to hold it square. You can't see the in the photo but they were necessary to help the cage retain its shape.

The second step was tricky. I had to make sure that the tower was placed exactly the right distance from the house. Too close, and the tower would lean away from the house, too far, and the tower would lean toward the house. The HB25B brackets I used only have adjustment holes every couple of inches.

I thought the solution was pretty clever. First, I mounted a bracket to the house at about the 9 foot level. I held it in temporarily with lag screws into the rim joist.

I used a plumb bob to drop a line down to the ground level. I build a two foot square frame using a couple of 2x4s and then placed it on a reference line below the plumb bob. 

Voila! Perfect placement of the hole directly below the bracket.

I dug the hole out through the frame. An ordinary shovel worked at first, but after getting down about a foot, it was very hard to use. I ended up digging out most the hole using a post hole digger. Since the post hole digger only nibbled out a bit of dirt each time, it took a while, but it wasn't really difficult. A nursery shovel (the kind you use for planting saplings) turned out to be really handy in truing up the sizes of the hole.

With four and a half feet of my two foot square hole, the next step is to get everything in place. The bottom of the hole gets six inches of pea gravel -- which allows condensation to drain out of the tower legs. Then the rebar cage goes in after. I set mine on a set of small bricks, and made sure each side was at least three inches from the side of the hole. You don't want moisture to leach into the concrete and rust out the rebar.

Last bit to go into the hole was the tower itself. I dropped two sections in, and then fastened to the house bracket mounted earlier. I built a small wooden fixture to hold a plumb bob line in the center of the tower. On a calm day, it's pretty easy to get the tower in line with the plumb line. Rohn only specifies the tower be vertical to within 1 degree, which is readily accomplished.

Some additional wire holds the cage to the tower sections -- so that nothing will try to move around while pouring concrete.

If you look closely, you'll note one more ingredient -- a DX QSL card, which is used to ensure good performance of the antennas attached to the tower.

OK, it's time to pour!

I rented an electric mixer from Home Depot. This puppy could hold two 80 lb bags of concrete mix at once. It was tough to get it to pour into the hole, but a stout piece of plywood helped.

Each bag of mix requires a bit less than a gallon of water. I used a knife to cut the top off a gallon milk jug. When filled up, it was the perfect amount of water per bag. 

The process for the pour went like this:
  1. Pour one jug of water into the mixer. This prevent the first bag of dry mix from sticking to the sides of the mixer like, well, concrete. 
  2. Put each bag of mix into the mixer. 
  3. Start the mixer. 
  4. Add another jug of water.
  5. Mix for about two minutes.
  6. Pour mix into hole.
  7. Repeat
So, you may be wondering -- when did he have time to measure another jug of water between steps 1 and 4? Well I cheated. I had a bit of help -- my eldest daughter, who happened to be seven years old at the time.

The job of filling the jug fell to her, and she was quite adept at it. We mixed 28 bags of concrete in a bit under 2 hours.

With the pour complete, it took seven days to reach 90% strength, so we had to wait for the next part -- and so will you.

Monday, January 5, 2009

Alas, Macworld, we hardly knew ye....

Well, tomorrow brings the last keynote of what is most likely the last Macworld of any import. Of course, IDG may well try to host Macworld without Apple next year. We all know how well that worked in Boston.

In any case, I don't think that trade shows really matter much any more. Back in the early days of microcomputers (back when we still called them that), trade shows were a pretty effective way to generate some buzz about your new product. The first Macworld was incredibly well attended. I worked the booth for my employer -- I was scheduled for two hours on, and one hour off alternating through the day, but the reality was that I worked seven and a half hours for three days straight. My feet hurt just thinking about it. (And this was back when we wore suits and wingtips at trade shows, too)

Today, one can generate quite a bit of buzz about a new product or service just by making a press release and a couple of Twitter tweets. The internet has us so interconnected that it's just not hard to communicate.

Of course, the other thing about trade shows is that they had gotten so big that your message was getting diluted. Consider what might have happened if Apple had introduced the iPhone and CES instead of Macworld. 

Chuq Von Rospach noted that Macworld caused all kinds of problems for Apple -- from people working through the holidays to messing with the delivery schedule for products. The real truth is that Apple has outgrown Macworld. Apple can generate buzz any time, just by calling a press event -- or perhaps by not calling one. That always gets the rumour mills hopping.

Apple will still have their annual WWDC as a platform for regular announcements. It's curious to me that Microsoft hasn't copied this idea. Sure, they have PDC -- but they only call for a conference when they feel there's some release of note. If they were smart, they do it every year. 

Sunday, January 4, 2009

Saturn S-Series: I Love Mine

Back in 1994, I decided I needed to buy a car. With a new baby, I needed a four-door automobile. At the time, I was driving a 1985 Honda Accord Hatchback.It wasn't a bad car, but it got horrible gas mileage. Unusual for a Honda, you say. Well, there were reasons for this.

The original Honda CVCC engine had a carburetor. As the emission standards changed from year to year, they kept adding more devices in order to meet the standards. I once worked on a 1982 Honda Prelude. This engine had about 7 vacuum hoses. By comparison, my 1985 had 70 vacuum hoses. And when those devices were not working correctly -- the engine wouldn't quite run correctly. Honda fixed this problem in 1986, when all their cars switched to electronic fuel injection. Not so for my little hatchback.

One hot July day, the Honda finally gave up the ghost with a cracked block. At the time the Saturn S-series was pretty new, and I went to look at them. I test drove an SL1 automatic that I really liked. I also went and test drove a Honda Civic Wagon. It wasn't as nice as the Saturn, but the dealership quoted me over $4,000 more. Heck, for that price, I'd buy the Saturn. So, I did.

I drove that car like crazy for the next nine and a half years. In that time, I put 144,000 miles on it. It was a great car. Never left me stranded, got great gas mileage -- and all on very little maintenance. It was a tough little car. OK, so at 144,000 miles, it burned a bit of oil -- you generally had to put in a half quart at each fill-up. This worried my wife, so, on her advice, we traded it in on another car.

The Saturn S-series really was a different kind of car. It was a great experiment by GM -- new design, new technology, new sales team. Sadly, though, the experiment didn't pan out, and now Saturn is just another label GM sticks on platform cars designed by other divisions.

Recently, when gas prices were over $4.00 a gallon, I bought another Saturn -- an 1995 SC1 manual. Unlike my 1994 SL1, it actually has cup holders. I'm amazed at how much I enjoy driving it. This is not a sports car, or a hot rod. It's basic automobile. Plus, getting about 30+ mpg doesn't hurt, either, even with gas prices down to a more reasonable level.

Too bad GM no longer builds the Saturn S-series. With more cars likes this, perhaps GM wouldn't be needing a bailout.

Saturday, January 3, 2009

"Novice" 40m Transmitter

Three years ago, I discovered the remains of a project in my junkbox. It was a transmitter Istarted building when I was waiting for my Novice license, in 1975. It had seen several evolutions, but never quite worked right.

The original was a 6DQ6 crystal oscillator feeding directly to the antenna. Part of the problem was I did not have any crystals! I later changed this to a 6GK6 / 6550 design, trying to feed it with an external VFO. While the 6550 had some impressive ratings, it arced internally when I tried to feed it 800 volts on the plate. I then revised this into a 6GK6 / 6146 design following an article in the ARRL Handbook, with a built-in solid-state VFO. This actually worked, but was really chirpy and had low output. I would later discover the reason for the low output -- a bad 6146 tube.

Over the years, the useful parts had been stripped away. So, when I started, it didn't look like much, as you can see below.

The resulting transmitter uses a design similar to those popular just before I received my Novice in 1975. The power supply has an ancient TV transformer in a full-wave diode bridge that provides 800 volts to the PA and 400 volts to the oscillator. An 0A2 regulates the screen voltage to the oscillator.

The 6CL6 functions as an electron-coupled oscillator, a design I borrowed heavily from the AA8V one-tube transmitter. It keys very cleanly through the cathode, without any attempt at shaping, with no chirp or drift.

The power amplifier uses a 6146, which is biased for cutoff without drive, so I didn't attempt to key it. The bias supply comes from a low-voltage transformer reverse-connected to the filament winding of he primary transformer. This means the key only has the oscillator cut-off voltage across the contacts, which is less than 10 volts. In all the old tube transmitter designs I've looked at, I've never seen this particular keying arrangement. Cathode-keyed designs typically developed grid bias across a resistor, which meant the PA was unbiased with no drive, so it had to be keyed. Grid-block designs typically keyed all stages, or maybe left the oscillator free-running. 

The 6CL6 drives the 6146 to about 2 mA of grid current (depending on the crystal), which is plenty. I originally used a 6146A that was a little soft and could only get about 40 watts out. The NOS 6146 in now gives about 110 mA of cathode current, which is about 90 watts input, and delivers a good 50 watts output. 

I first used this transmitter in 2007 for the ARRL Straight-Key Night "contest". It didn't look like much as you can see, with the unused front panel holes and no cover or bottom. However, it did work pretty well. 

The next year brought some changes. I removed the old front panel and built a new one that was a little bit shorter. I repositioned the meter so the whole business was a bit more compact. I added a cover made out of perforated aluminum, and a bottom panel and feed. The rig also has readable control labeling, courtesy my wife's label maker. This year, I added a T/R relay that switches the antenna and provides muting for the receiver. The result is a pretty handsome little transmitter, as you can see at the top of the article.

In the days when many people were crystal controlled, people generally tuned around for answers to their CQs, since someone answering might be many kHz off your frequency. That practice was long gone by the time I got my Novice license. Using a crystal-controlled transmitter today means you have to be able to call CQ and have people answer you on your frequency. That first year on SKN I was locked on 7075 kHz. Over the last couple of years, I've purchased about eight crystals for 40m. I've made a couple of dozen contacts with this transmitter, and it has been loads of fun to build and operate.

Of course, a transmitter needs a receiver, and that is another story.

Friday, January 2, 2009

Welcome to My Weblog

With the new year, I'm sure everyone has made some resolutions. We like to think that the beginning of a new calendar means we can fundamentally improve ourselves. Let's hope so. One of my resolutions was to start a weblog -- and so, here it is.

You may be wondering about the title -- why The Boring Ham Radio Part? Well, that's a funny story. I used to work with a fellow here in Atlanta, and discovered he was an amateur radio operator. We became fast friends. As fate would have it, Mike changed jobs and moved away. But, we still kept in touch.

He and his wife Lisa (also a ham) send out a long letter with their Christmas cards. I always enjoy reading this letter. They talk about their many cats, their hiking and vacation trips, and anything else interesting they have done. The part that I read first, however, is the part that Lisa always marks "Here comes the boring ham radio part." 

So I guess boring isn't so bad.