All you need to know about old Sol and how he affects your quality radio time.
Monthly Archives: November 2012
Spiderbeam Antenna
Spiderbeam in Germany make a series of the unique antennas.
Go to this link Spiderbeam Antennas and have a look at how they are made. Spiderbeams do have some unique features and perform extremely well.
73, Lee ZL2AL
Recycled TV Antenna for Two Metres
Build a 2M yagi antenna from recycled materials. It is not difficult and you can save the environment. Go to this link Recycled TV Antenna
73, Lee ZL2AL
DX Net Rant by ZL3JT
In the beginning, when God created radio, some people, including me, found that I could “work DX” on a “DX net”. In fact I went on every net I could find to satisfy my thirst for new countries and Islands in the IOTA program.
I looked up to people like Jim Smith VK9NS, Roy Jackson ZL4BO, N6FF Dick Wolf, Dr Saleem OE6EGG, Zedan Hussein JY4ZH, Percy Anderson VK4CPA… who ran these splendid sessions for those who thought it was a hellava good idea to be involved.
Little pistols with bits of wire got a chance at some “real” DX, if and when they also joined in these nets on 20m and 15m or 40m The oldest and “best” was the ANZA net on 21.205 When I had my “novice Morse” I used to listen with anxiety to the activity generated each day on the 15M ANZA Net knowing that I couldn’t participate because it was out my of my allocated frequencies… It sure was incentive to pass the Morse test and upgrade to a full call……
But over time, a couple of years or so, I realized that there was no challenge working DX with someone supervising the QSO…Saying “Over rover” at the appropriate time. …Repeat his report…You’ve got the number wrong!. But if that’s the way you want to do it, who am I to criticize? I did it…then I got into using Morse code for DXing…..
Things changed dramatically in my mind…I could do it myself…All by myself…. It’s much more satisfying…and it’s bloody difficult to run a net on CW… So I got my DXCC Honour Roll all by myself, mostly with CW… I didn’t have to count any of the QSOs I had done on DX nets which was even more satisfying…But that’s just my way.
For something to do, I went on SSB nets as a DX station…It was good to do that for those who only work DX nets. But DX is where you find it …every time…. If it’s on a net, then join the net, work the DX station if you want…. What the hell does anyone else care? It’s nobody else’s business how you work DX. But I bet you won’t find nets on all bands, you will seldom find a DXpedition on a net….. So you have to forget nets, and join the pile up…
Pile ups are inversely proportional to the rarity of the DX station…remember that because you have to get craftier….. You have to make your own luck in a pile up!
73 and GD DX
Duncan, ZL3JT
The Founding of ZL3X
SHEARING THE FUN – THE FOUNDING OF ZL3X by Mark ZL3AB
It all started innocently enough. I’d had a lot of fun in the BERU contest operating from home as part of the “ZL3 Earthquake Survivors” team in February 2012, when I asked if there was any interest in a serious multi-op effort in the CQ WW RTTY contest coming up in September. The answer was “yes!” and “The Quake Contesters” were born.
Starting from scratch presented some challenges.
Although we had all dabbled none of us were serious regular contesters and we were not blessed with acres of land to build a super station. K3LR or W3LPL this clearly wasn’t going to be!
ZL in general and ZL3 in particular is not exactly flush with contesters or contest groups (ZM1A and ZM4T in the North Is being the only regular groups currently operating and there are probably less than a dozen other operators in the whole country who regularly enter any of the international contests) and we were going to need more operators than we had.
Location: Based in Christchurch, we wanted a quiet site which ruled out the local amateur radio clubs as they had stations in residential areas. Then we had to find somewhere that hadn’t been damaged in the earthquakes we had in 2010 and 2011.
After an initial search for somewhere by the sea proved unsuccessful, I was out for a run one day pondering our options when the Port Hills, the rim of an extinct volcano at the southern end of the town, drew my gaze. Then it hit me. The local city council had buildings up there and I wondered if they would let us use one? I called the council and as luck would have it, I ended talking to a guy I went to school with many years before! “No problem” he said when I outlined what I wanted and he offered us a sheep shearing shed with a kitchen and power which was 300m above sea level and with views from the west through north to the south-east, perfect for where we needed to aim the antennas. We had our site.
Next we needed to start planning for the day so in that time honoured ZL tradition we went to the pub. There we identified some other ops to approach and set out a list of gear and antennas. We all agreed that as this was a serious effort the first item on the list had to be a kettle for making tea and coffee! Other than that our goal was to call CQ at the start of the contest so we determined we would strictly adhere to the KISS (Keep it Simple Stupid) principle. Normally callsigns in New Zealand are issued with two or three letter suffixes. We decided we needed a callsign with a one letter suffix which you are allowed to request for use for special events and contests. When we had a look at the options ZL3X stood out as the obvious candidate.
We decided to enter the Multi-Single low power category for two reasons:
1. We had major concerns about interference between stations with RTTY being a full duty mode as we had no band pass filters and the rigs were to be set up quite close together; and
2. If we managed to get it going, the “Mult” station as a search and pounce station meant that being inexperienced our ops were not under any pressure on that station to run and thereby deal with pile ups.
Come the day we were ready (or thought we were). The contest stated at 12 midday Saturday New Zealand time so the team of Phil Holliday ZL3PAH, Andrew Barron ZL3DW, Don McDonald ZL3DMC, Graeme Kerr ZL3GK and I headed up the hill at 9am. 
Amazingly the Port Hills were bathed in sunshine except for the part we were going to be operating from! When we got up there visibility was down to about 30m but as Don ZL3DMC noted, “…at least we are not an astronomy club”. (Lesson one: Conditions on a hill may materially differ from those on the flat. Always bring warm clothes).
Now we would have loved stacked yagis and four squares but following the KISS principle we took a more modest approach. Our antennas consisted of a hex beam on a 5 metre pole for 20-15-10m and a fan dipole on an 11m aluminium pole covering 40-20-15m.
It was supposed to do 10m as well but after we put it up we could not get it to load on 10m. (Lesson two: Always check your antennas before you leave home). The rigs used were a Kenwood TS2000 and an Elecraft K3.
Once the antennas were up we had an hour before the contest to set up the radios and N1MM on the two laptops.
(Lesson three: Never leave it until an hour before a contest to set up radios and network two laptops). After much frustration we could get N1MM networked and logging from both radios but we could not get the cluster going or show accurate info for each laptop. We never did figure either issue out. (Lesson four: Set up a fully functioning network in the days leading up to the contest and write all your settings down).
Because of our interference fears we put toroids on all our leads. We even put toroid on toroids! The rest of the lads drew the line when I started eyeing up their shoelaces and some passing sheep. Despite that we were still worried but to our major surprise we had no interference issues.
After a “wee dram” to set us on our way we were off. We then immediately hit a problem. If one station was transmitting the other one couldn’t. We couldn’t figure it out until we looked at the network set up and somewhat sheepishly noticed that the software interlock was on. Problem solved! (Lesson five: Read up on the software you are using before the contest).
We all had a blast as did the wind at times. Although watertight the shed was hardly airtight with a slat floor in parts and louvres on the windows so it got pretty cold, not to mention noisy with the wind rattling the roof quite dramatically at times. After driving up the hill for the Saturday night shift and with visibility down to about 20m due to the mist, I did seriously wonder what on earth I was doing up there. I did that shift in a sleeping bag.
From a receive perspective the site was amazing. There was no local noise as the nearest houses were over a kilometre away and even with our low, basic antennas we managed great copy. I will never forget seeing an Italian station signing /QRP all perfect print.
However transmit was a different story. QST Contributing Editor Ward Silver N0AX once told me he did a study of which DXCC entities were, on average, the farthest away from all the others. The trio of ZL/ZL7/ZL8 “won” that competition going away (in case you are wondering Croatia 9A was the least distant). From Christchurch the nearest amateur population of any substance is VK2 which is 2,100 km away or approximately the same distance as Los Angeles to Dallas. Los Angeles to Christchurch is five and a half times further! We realised just how far we were from the action by the number of stations whom we could read perfectly but who could not see us. A combination of low power and the fact that many of these stations were clearly not beaming our way meant we (and they) missed out on a number of QSOs and in the case of the DX station more than likely a multiplier. And it wasn’t just us. Many times we saw VK’s in the same position especially in the last four or five hours of the contest. (Lesson six – for you this time: Turn your beam when you are not busy, you never know who might be lurking off the back).
By the end of the contest and in what turned out to be the first ever multi-op effort in the CQ WW RTTY contest from ZL, we had 519 QSOs and a claimed score of 417,439 points. We were pretty happy and as Phil ZL3PAH noted, “… contesting is a lot more fun when you do it as a team”.
Quotes of the weekend:
Don ZL3DMC “This K3 is broken”. We later realised the Hexbeam was facing 180 deg from the direction we thought it was. (Lesson seven. Hexbeams have a great F/B ratio).
Family friend who was staying at my house on the Saturday night: “Why don’t you just use Skype?”
PostScript: The Quake Contesters entered the 2012 CQ WW SSB as a Multi two entry and put a lot of the things we had learnt into practice. We had a second beam higher up, bandpass filters, more power, a reliable cluster connection and more operators. This lead to a significant increase in our score with 2227 QSOs and over 1.9m points claimed and we had fun. We plan to enter many of the big contests in the future.
73, Mark Sullivan ZL3AB
My Favourite DX Stories by W4KVS
My Favourite DX Stories: Notes From a Beginning DXer
By Kim Stenson, W4KVS
[email protected]
You don’t have to spend a lot of money on a plane ticket to travel the world. From the comfort of your own shack, you too can be a globe-trotter. All you need is a radio, an antenna and the desire to make that QSO. By seeing the world through your radio, you get the QSL card without the jet lag!
Like most DXers, I enjoy reading about (and working) DXpeditions to exotic parts of the world. I have also found that there is a great deal of adventure on my end of the microphone. One of the great attractions of Amateur Radio is the ability to contact fellow operators in distant lands. Accordingly, I find a great deal of pleasure in reading about the DX adventures of hams, especially those with modest equipment. With 100 W and a modest antenna system (wires for HF and a small 3 element beam for 6 meters), I have had my share of exciting DX stories. Here are some of my favourites.
Listen to the Whole Call
One evening I was tuning around 20 meters when I came across a station calling CQ. As the operator announced his call sign I immediately recognized the SV prefix as Greece; my first impulse was to keep tuning as I already had worked several SV stations. For whatever reason, I decided to remain on the frequency and to listen carefully to the call — I soon realized there was something different. The operator was adding “stroke alpha” after his call. I recognized that it was Mount Athos, one of the rarest DXCC entities. I had recently read that Monk Apollo, SV2ASP/A, the only licensed HF operator at the religious enclave on the Aegean coast. To my knowledge, he had been off the air for at least a couple of years, and I thought my chances of ever getting Mount Athos were next to impossible.
Knowing that the airwaves would soon erupt into a frenzy, I frantically threw my call in, “W4KVS.” The operator only copied part of the call and came back with, “W4, W4?” Not knowing whether he had heard me or another W4 station, I again threw out my call, “W4KVS, W4KVS.” To my great surprise, he came back to my call and we had a short exchange. I asked him if I was speaking to Monk Apollo and he confirmed that it was indeed him on the other end. As soon as I signed off, a huge pileup ensued, one that I had no chance of breaking if I had not been the first to call. This contact is a good example of listening to the whole call. If I had not listened carefully, I might have dismissed the call as a routine SV station and missed an extraordinary DX opportunity.
Out of Africa
A similar situation took place on 10 meters one Saturday morning in winter when I came across a 3DA (Swaziland) working a huge pileup; 3DA0WPX was working simplex, and after the operator announced, “QRZ?” all I could hear was a giant whine. Any attempt to make a contact would be futile, as there was absolutely no way I could get through the pileup. I had never heard 3DA before and there was no telling when I would have another chance. Disappointed and somewhat frustrated, I moved on. Later that afternoon I was tuning 10 meters again, and suddenly I heard 3DA0WPX calling CQ again. Frantically, I answered his CQ and Andre came back to me with “You are 59, nice signal.” I also gave him a 59 report, but resisted the urge to tell him I was using an attic antenna. Within seconds, the frequency erupted into what seemed like hundreds of signals, most of which, I am quite sure, were stronger than mine.
It’s not Easy being Greenland
Pileups sometimes appear insurmountable but they often have ebbs and flows. A huge pileup can be in progress and then drop to a manageable level, only to be soon followed by another huge pileup. One morning I heard OX3OX in Greenland on 6 meters SSB working a fairly large pileup. The prefix OX is not that common on HF, and on 6 meters it is a real catch. I started throwing my call in; at the time, I was only using an omnidirectional loop antenna. After calling for a while, the pileup seemed to be getting smaller, and instead of handing out 59 reports, Ole, OX3OX, started giving out 55 reports, and finally 51 reports. The weaker stations were getting through, but could he even hear me? Finally, he did hear part of my call. After several repeats, Ole was finally able to copy my call and I exchanged reports with him. My report was 33 — not great by any definition, but I was able to get OX on 6 meters. As I often do, I listened for a while after the contact. He continued to call CQ, but did not raise anyone. I had been on the bottom of the pileup.
Persistence Pays Off
Just like everyone else, I was excited about the first DXpedition to Ducie Island, VP6, hitting the airwaves — it would be the first station to operate in a new DXCC entity. I, however, had my doubts about working it. Everyone needed Ducie Island, and I expected the pileups to be far worse than any I had yet encountered. After all, everyone needed this one. I believed my best chance of making a contact would be toward the end of the DXpedition.
One weekend afternoon, I heard VP6DI on 15 meters SSB. The operator was working a fairly wide split above his calling frequency, and I tried to determine his pattern by switching VFOs; however, I could hear very few stations calling because both the calling stations, and Ducie were located west of my location. If you cannot hear the calling stations, it then becomes difficult, if not impossible, to determine the DX station’s operating pattern.
I took the best action I could — I planted myself on what I thought to be a clear frequency and started calling. I tried for an hour or so, but I was not successful and so I gave up, believing it futile to keep calling. I turned the dial and began looking for other DX. I searched the band for a while and did not find anything interesting, so I decided to go back to chasing Ducie. I again found what I thought was a clear frequency and made a call. VP6DI came back to another call and then I heard “QRZ?” I made another call, and suddenly VP6DI came back with, “W4KVS, 59.” I shot back with a report and then revelled in my success. I still have trouble believing I actually worked VP6DI under those conditions.
Getting Guam
Asia and the Pacific area are very difficult from my location in South Carolina, and any contacts in those areas are hard to come by. Guam was one country I almost never heard, and I was very excited to hear AH2R on 15 meters during a contest.
It was the second day of the contest with only an hour to go, and AH2R was not getting many calls. It looked like I was going to be able to bag a new one fairly easily. I threw in my call literally dozens of times, but AH2R was not hearing me. Occasionally, the operator would catch part of my call and ask for “W4” or “VS.” Frustrated that he was not able to get the entire call, I decided to throw in the towel. I looked at my watch and there was only about 10 minutes left in the contest. Then I thought to myself, “Why not continue for the next 10 minutes — what do I have to lose?”
I continued calling with the same results: the operator would hear “W4” or “VS,” but not my entire call. The clock continued to tick and finally there were only a few seconds left before the contest ended. I had time for one last, most likely, futile attempt and made the call, “W4KVS.” Incredibly, AH2R came back with, “W4KVS, 59.” With that, the contest ended, but I had a new country.
Stuck in the Middle
One of the most exciting aspects of DXing is finding the unexpected. One Saturday morning, I heard a fairly weak station calling CQ on 20 meters. The station had strong audio, but it was sandwiched between two very loud stations. No one was answering the CQ and the interference was troublesome, but I had a feeling that this might be something out of the ordinary. From within the interference, I finally managed to copy the station, 4W6MM. East Timor was, and remains, one of the rarest DXCC entities, and I never thought I had a chance of working the one active station located in that country.
Two thoughts immediately raced through my mind. First, 4W6MM was not very strong. In the clear, I could hear him, but it was quite likely that he would not be able to copy my signal at all. It would be very frustrating to hear a rare DX station calling CQ with no one answering and him not being able to hear me. I could have a another possible AH2R situation on my hands. Second, I would have to time my call just right. I might be able to hear him with one of the strong adjacent stations transmitting, but not with both at the same time.
I listened for a few seconds and suddenly there was a lull in the noise. I quickly threw in my call, and to my great surprise, 4W6MM came back with “W4KVS, 59” just as one of the adjacent stations started transmitting again. Nevertheless, I shot back his report, which he acknowledged. Incredibly, I heard 4W6MM the following Saturday in a contest and was able to work him again. Both contacts lasted only a few seconds, but they were definitely among my most memorable.
Sometimes You Feel Like a Nut…
St Peter and Paul Rocks is also one of the most sought-after DXCC entities. It is a place that is seldom activated; I had never even heard a station from this Brazilian island. Joca, PS7JN, periodically operated from this remote island, but he worked primarily RTTY. I was set up to work RTTY with my computer sound card and interface, but I had never been able to have a successful RTTY contact. The few times I had tried, I was not able to make a contact.
Toward the end of one of his mini-DXpeditions, I noticed that that ZW0S, a Brazilian special event call sign, was frequently spotted, but with relatively few callers. Now was the time to see if I could work St Peter and Paul. I turned on my computer and brought up the RTTY software. I tuned for ZW0S, and suddenly he appeared on my screen. I hit the macro and transmitted, “DE W4KVS W4KVS W4KVS.” Immediately, ZW0S came back with “W4KVS 599 599.” I happily gave Joca his report and completed my first RTTY contact, which just happened to be a rare DXCC entity.
“Snappy Operators on a Completely Quiet Band”
Cameroon, TJ, is another country high on the DXCC most wanted list and I was glad to find out that Roger Western, G3SXW, and Nigel Cawthorne, G3TXF, planned a DXpedition there in the spring of 2004. One evening, I was able to copy Roger, TJ3G, on 20 meters CW working split. There was a pretty good pileup, but I kept throwing my call in. After some time, Roger indicated he would be taking a short break. I stayed on the frequency, hoping some of the others would not come back. It worked. In a few minutes, Roger came back and I got him on the second call. I was also able to work Nigel on 17 meters near the end of the DXpedition. Two great contacts!
Later, both Roger and Nigel said they thought 20 meters would be their best chance to find suitable propagation, providing long openings to all areas, and they enjoyed the “snappy operators on a completely quiet band.”
Even with a modest setup, you can have a lot of fun DXing. SSB, CW and RTTY on both HF and VHF have allowed me to participate in some great DX encounters. DXing is an adventure, and I can’t wait for my next DX experience. I know it is out there.
Kim Stenson, W4KVS, is an Amateur Extra, first licensed in 2000. Retired from the US Army, Kim is a former infantry officer who saw combat in the Persian Gulf; he counts the Bronze Star and Combat Infantry Badge among his military honors. Kim received his BA from Washington and Lee College in Virginia, and his MA from Norwich University. He is presently chief of the Preparedness and Recovery Branch of the South Carolina Emergency Management Division.
Pozidrive, Philips & Robertson Differences
Q: What’s the difference between Phillips, Pozidrive and Robertson (square) screws?
A: Philips drive screws are the screws that have cross-slots that look like an X, stamped into the head. Patented in the 1930’s, these were a vast improvement over the antique “slotted” screw, which tended to cam-out easily and were difficult to drive with power drivers.
Robertson (square) drive screws were patented inCanadain 1908 and address problems that the Phillips driver doesn’t quite solve. They allow the screw to be placed on the driver prior to the screw being placed in position. What this meant was that for the first time you could start a screw overhead or in a tight spot without an extra hand holding the screw onto the driver.
Pozidrive screws are the European answer to the Phillips shortcomings. The differences are subtle. At first glance it appears to be a Phillips, but on closer examination you’ll notice a second set of cross-blades at the root of the large cross-blades. These added blades are for identification and match the additional makings on the head of Pozi-drive screws, known as “tick” marks. So the marks are for identification. Identification of what?
Two features of the Pozi-drive screw and driver combination make it unique, and superior to the Phillips. First, the tip or the Pozidrive driver is blunt, which also helps it to seat better into the recess in the screw, unlike the Phillips which comes to a sharper point. This becomes a problem as the tooling that forges the recess in the head of the screws begins to show signs of wear. The recess becomes more and more shallow, which means the driver will bottom-out too soon and will cause the driver to cam-out. The second unique feature is the large blades on the driver have parallel faces, where the Phillips blades are tapered. The straight sides of the driver allow additional torque to be exerted without fear of cam-out. Knowing this, we can see why a Phillips driver will have problems driving a screw with a Pozi-recess, as a Pozi-driver would have little luck driving a Phillips head screw. One more tip. In a pinch it is possible to drive Pozi-drive screws with a Phillips driver, but you will need to grind down the tip slightly, and expect some slipping to occur.
73, Lee ZL2AL
How A Current Balun Works
How a 1:4 Guanella-Balun (Current-Balun) Operates – ByJerry Sodus, KM3K
1. The purpose of this article is to show how a 1:4 Guanella (current)-balun changes an impedance level by a multiplier of four; for example, 50-ohm coax to a 200-ohm antenna.
Although this is not a “how to make the balun” article, some design information is given for completeness.
2. Also, just to let you know…the Guanella (current)-balun can be turned around to go the other way; for example, a 50-ohm coax can be changed down to 12.5-ohm (say for a Yagi-antenna or a vertical-antenna). We’ll cover this later in paragraph #12.
3. BTW, Guanella came up with this idea in 1944.
In 1985, Roy W7EL gave Guanella’s idea the name “current-balun” because the balun’s output supplies equal current into/out of the output pins and that is a good thing.
4. It is important to put out of your mind any idea about flux-linkages and conventional-transformer action. Those concepts have nothing to do with this article.
5. The 1:4 Guanella (current)-balun is made from two 1:1 Guanella (current)-baluns.
Except for winding direction, they should be as identical in construction as possible to minimize any variation in signal delays; variations will increase signal loss at the higher frequencies.
6a. The 1:1 Guanella (current)-balun can be made up in several different ways:
A) coiling coax,
B) winding a transmission-line (coax or two-wire) on a toroid-core or rod; ferrite core/rod preferred,
C) threading coax thru ferrite-beads.
6b. Figure 1 has the usual schematic used for a 1:1 current-balun.
6c. To emphasize that the transmission-line mode is working here, lets use the schematic as in Figure 2.
6d. Here is a key point.
We’ll assume that any signal loss thru the balun will be small enough that we can ignore it.
So, whatever voltage is at the input of the 1:1 balun is what we’ll see at its output.
In other words, we assume the signal’s voltage-level is not attenuated by the 1:1 balun.
In practice, we can approach this goal by using high-quality transmission-line and keeping its length short.
7. You connect up the baluns in this way as shown in Figure 3 below.
7a. The inputs are in parallel.
That means that any current going into terminal P3 splits in two, half goes up to terminal 3 and the other half will go down to the other terminal 3. At terminal P1, the currents coming out of each terminal 1 combine at P1 to flow back to where it started. Although P1 and P3 are where we will eventually the feed-line from the transmitter when we use the balun, for us right now, the feed-line is not connected.
7b. The outputs are in series.
Notice that if we were to connect an ohmmeter to P1 and P3 at this time, we’d read a short-circuit.
7c. Next connect a load ‘RL’, which we assume is a just a resistor for our purposes at this time. See Figure 4.
You may recall that a resonant-antenna is just a resistor, in other words, a pure resistance (no reactance). It’s interesting that, in Figure 4, the current going around the “inside-loop” never gets to the load RL. The “inside-loop” is from P3 going down to balun-A’s terminal 3, then to terminal 4, up to balun-B’s terminal 2, over to terminal 1 and then to terminal P1.
8. There is a term “input impedance” and we’ll use the symbol “Zin” for it.
In case “input impedance” is a new idea for some, here is a short explanation…
For us electronic folks, it is the value of impedance we’d measure at a test-frequency if we could connect up a special kind of alternating-current ohmmeter to terminals P1 and P3 in Figure 4. That value of Zin would replace the entire circuit to the right of P1 and P3.
For us right now, we are only concerned with the idea of “input impedance” and not with any actual value.
9. We’ll use the schematic in Figure 5 to find the power going into Zin.
A key point here is to remember this is really the power going into the input of the 1:4 balun (at P1 & P3). In Figure 5, we are not concerned with the transmitter or its output-resistance. All we really care about is that there is Zin and a voltage across it; we’ll call that voltage “V”.
Recall that power going into a resistor is equal to ‘the voltage across the resistor’ times ‘the voltage across the resistor’ divided by ‘that resistance’.
So using our symbols, we can write the “power into the 1:4 balun” equals “V times V divided by Zin”.
10. Next we need the power going into the load RL. So, we need to know the voltage across RL. Here is how we’ll figure out what its value is.
10a. Recall that the voltage across P1 and P3 is V.
This is the same voltage across pins 1 and 3 at each of the 1:1 baluns.
10b. In step 6d, it is written that the same voltage V will be at each output of the 1:1 baluns.
10c. Step 7b has the outputs of the 1:1 baluns connected in series. So this means V plus V equals 2V is across the load RL. (If you have trouble understanding this, perhaps this may help. Just for now, pretend that each 1:1 balun output is a battery. So we have two batteries connected in series; just like in a flashlight and the light-bulb is the load. If each battery is 1.5 volts, we’d have 1.5 volts plus 1.5 volts equals 3 volts across the load.)
10d. The “power going into RL” is “2V times 2V divided by RL”.
11a. Now we are at the KEY section; the reason for this article. We are assuming there is no power lost in the baluns and that is a reasonable approximation throughout most of the 1:4 balun’s passband. We can write…”POWER INTO THE 1:4 BALUN” equals “POWER GOING INTO RL”. Paragraph 9 gives the “power into the 1:4 balun”.Paragraph 10d gives us the “power going into RL”, so we can write here… “V times V divided by Zin” equals “2V times 2V divided by RL”. Doing all the algebra, we come up with …..”RL equals 4 times Zin”. So we have proved we have a 1:4 impedance-ratio.
11b. An example ……….if Zin is 50-ohms, then RL is 200-ohms.
11c. Another example…..if Zin is 75-ohms, then RL is 300-ohms.
12 If we turn the 1:4 balun around to get a 4:1 balun, we can step-down in impedance.
For example, 50-ohms divided by 4 equals 12.5-ohms (maybe for a Yagi antenna); see Figure 6.
13. Comments about the transmission-line used in a 1:1 Guanella (current)-balun:
13a. The value of its characteristic-impedance Z0 (that is Z and a zero; pronounced Zee naught) is important.
13b. The 1:4 balun has a low impedance side and a high impedance side. Whatever the high impedance side is, divided that value by two and that is the characteristic impedance to use in the 1:1 Guanella (current)-balun.
13c. Here are examples of some values for 1:4 Guanella-baluns…
for 50-ohm to 200-ohm, Z0 is 100-ohm.
for 75-ohm to 300-ohm, Z0 is 150-ohm.
for 50-ohm to 12.5-ohm, Z0 is 25-ohm.
13d. You can make your own transmission-line (two-wire or coax); see Sevick’s “Transmission-Line-Transformers”.
13e. The more you deviate from the design Z0, the more power you lose at higher frequencies.
14a. The 1:4 concept can be extended to other ratios like 1:9 and 1:16 and 1:25.
14b. But more 1:1 baluns are needed; the 1:9 uses three; the 1:16 uses four, etc.
14c. The Z0 formula changes also; for 1:9, divide the high impedance by three; divide by four for the 1:16.
15. For completeness sake….it is possible to make a 1:4 Guanella-balun on just one core (in other words, two 1:1 baluns on one core paying proper attention to all pertinent details); however, that design approach should not be used if the load is grounded (virtually or actually) at its center point.
I hope this article is of some benefit in explaining how the 1:4 Guanella (current)-balun “does its thing”.
73 Jerry Sodus, KM3K
South-Mountain-Radio-Amateurs Club
Audio Dynamic Range
Audio Dynamic Range
What is you audio dynamic range? This mostly applies to SSB transmissions but could also apply to FM and AM as well. Simply put it is the difference between no modulation during key down and your modulation peak in dB.
Your dynamic range listed below will give you an idea on how your audio is perceived by the other contact.
- 10 dB, which is very harsh and tiring to listen too. Much background noise including fans, road noise, air-conditioning, dogs barking and in general background clutter noise. Your contact will ask for repeats a lot and in general your QSOs will be short.
- 20 dB, decent audio range with a little audio background noise. QSO’s will last longer. Very little repeats. Most stations fall into this category.
- 30 dB, your contacts will complement you on you audio, tonal quality aside; you will find folks will like to listen to your transmissions. Communications in weak conditions will be generally more successful.
- 40 dB, you are now into broadcast quality transmissions. This is not easy to obtain but with proper microphone techniques and mic gain settings most any transceiver can obtain this level.
- 50 dB, this is where you need to be if you plan on running a Linear Amplifier. With a +30 dB over S9 signal to your contact, your un-modulated signal will still be an S6 on their receiver. Poor dynamic range is the reason people ask if you are running a linear amplifier.
For FM you will need a deviation meter but with a good oscilloscope you could use the same method as you would use for AM. For AM you will need an oscilloscope to look at voltage level from no modulation and modulation peaks. For both FM and AM, this can be derived from a monitor receiver speaker output. SSB is much easier. Look at the peak signal as monitored from a nearby station. The difference in the peak reading to your modulating signal to the level received while not modulating is the dynamic range. If you have a lab grade watt meter you can look at the power output from the radio or amplifier. The formula is:
Log (power max/power min) x10 =DynamicRangein dB.
An example of a 1500 watt signal with a non modulation level of 100 mW is shown below:
Log (1500/.100) x10 = 31.76 dB
As you can see, 100 millawatts can transmit quite a lot of signal or noise. Some of this noise could be generated in the transmitter but generally it is from the microphone environment. To check you audio level, transmit into a dummy load and watch the output with no modulation. If you see a level indicated, turn you microphone gain down to zero. If the level drops to zero your microphone level is the problem with your low dynamic range and your audio environment.
Several things can be done to improve you dynamic range.
- Try to pick a quiet place for your station.
- Close the door to your shack.
- Use the microphone between 3 and 6 inches from your lips.
- Your ALC should read 10 dB or less.
- Avoid excessive compression. It is mostly microphone gain with a little filtering.
- Speak directly into the microphone, not on the side.
- Use a wind-screen (foam rubber) over the microphone.
- Be aware of cooling fan noise. Placement of fan related gear (amplifiers) is important.
- Use a suspended microphone. They pick up less desk noise and vibration.
- Avoid a room that has no rugs or drapes. Echoes don’t help and can make communication quality very poor.
- Make sure the TV and stereo cannot be heard.
These are the most prevalent items I hear being done in QSOs. If you’re mobile, roll up your window. Some FM mobiles have so much vehicle and wind noise their transmissions are unintelligible.
These are just a few suggestions on making your home station and mobile environment much more pleasant to listen to. Work with other hams for a critical ear. Now have fun.
Mike Higgins – K6AER
160 Inverted L Antenna
160 Inverted L Antenna – by N4JTE.
Between watching unending Law and Order repeats and the XYL’s Lifetime movie sagas, compounded by a dead 40 meter band here at night, I became so totally bereft of late night activities that I got the bug to get back on 160 meters again with something that would fit in my backyard. I have had, in previous QTH’s, the luxury of a full size 160 dipole, those were the days.
Well, 240 plus feet at any reasonable height is beyond my backyard limitations as I am sure it is, along with many of you. The 160 band is to me, a throwback to my AM and SWL days as a youngster when I would lay in bed at night with my crystal radio and listen to all the AM broadcast stations I could discern and check them off on my Knight’s Radio Log. Those days, are to me, the genesis of my love for the magic of radio, some of those AM stations are still legendary! Enough nostalgia.
I wanted to get back on the band with a respectable signal and try out the much discussed and prevalent 160 inverted L antenna. Previous to the inverted L, I tried a few ideas, some of which I am sure others have attempted also.
PREVIOUS ATTEMPTS:
1; 80 meter dipole, coax fed. Whew, lucky I did not burn something up, I know why it stunk but there are still some out there that figure if their good old trusty tuner loads up and somehow a length antenna seems too work on 160 they are good to go, NOT! Besides the neighbors getting tvi, your tuner and feedline were probably contributing to global warming.
2; 165 ft. 40 edz at 60 ft. ladderline fed. I really thought this antenna would work as its only 60ft. short. The fact was that my 3kw tuner told me that with anything over 100 watts, I was dreaming, as Christmas came early with all the flashing lights inside the tuner.
3; The good old G5RV with the shorted feedline and ground plane approach. I’m sure I remember a contact or two on a quiet night but pretty lame imho.
160M Inverted L .
There are a lot of 160 designs out there on the internet with quite a few adding coils etc to match shorten verticals, or top loading with various configurations. My feeling is that the coil losses and tricky matching problems with top loaded wire antennas make the inverted L the way to go for simplicity of construction and relative ease in matching 50ohms.
The inverted L is what it is; picture your Hamstick or any vertical and bending it 90 degrees halfway up and expecting some improvement over a nice simple straight vertical. Let’s be aware of the physics involved and keep our expectations within reality.
But: That’s the mystery and fun unique to the 160 band, anything that approaches a well thought out antenna, even in a restricted place will compete well. The really big guns with the phased 120 ft towers and 4000 buried radials only show up for the contests. The rest of us peons have a pretty level playing field when we are content to work a new state or keep in contact with friends around the country, with the occasional DX station popping in to say hello.
THE CONSTRUCTION:
The best I could do here was to get the old trusty 2oz weighted fishing line over my now bare 65ft. maple tree. Hobby money is tight here so I scabbed together 120 ft of insulated # 14 wire form previous endeavors and pulled back some masonry line. Taking care to keep the ends from tangling, the string was attached to the 60 ft. midpoint of the insulated wire and hoisted up to the top of an outside branch on the tree with the feed point end about 6 ft. off the ground.
FIRST ATTEMP:
Because I had nothing better on first thought and it was getting dark I ended up having to slope the remaining 60 ft. to a tie off point in the backyard which resulted in the end at about 10 ft. off ground. I hooked up two raised insulated radials at 120 ft. long each and hung them up at 6ft. high along the wood fence. Definitely not as symmetrical as I would have preferred with some zigs and zags thru the available branches etc. but ran them at 180 degrees from each other. Be advised there will be a lot of voltage on the radial ends and make a supreme effort to isolate the ends from any human contact.
RESULTS:
Not bad, first of all the amp, AL80B, was finally showing some life and providing 400 watts indicated. Reports were good from local to 1500 miles out but the S/N, noise was horrendous, so I figured it was time for some improvements.
SECOND ATTEMP:
Well, I was happy to be heard and the amp and 3kw tuner were silently applauding my work so I figured lets work on the noise situation. I figured out a way to get the horizontal portion over a nearby tree at about 45 ft. high, and try to get closer to a flat top configuration, but unfortunately it is only about 40 ft. away. End result was that the last 20 ft ended up coming down in a vertical direction to the tie off point, sorta ended up with a skewed inverted U configuration.
Voila! Ended up with a relatively flat 1.5 to 1 on 1865. I know that can be misleading, especially when using a bizarre shaped vertical, but it works. See note #5 in final comments.
FINAL COMMENTS:
1; If you are in tight restricted environment, the inverted L will get you on the air with a respectable signal and good match to 50 ohm coax.
2: Yes it will be noisy in an urban near field environment; I use my 40 meter antenna as a listening antenna when my local noise competes too much.
3; I placed a 1 to 1 current balun at the feedline junction; I did not see any significant noise reduction.
4; From talking to other Hams more advanced and experienced with the 160 inverted L, I found a few that liked the 3/8 wl configuration as it moves the current point further up the antenna and improves efficiency beyond the 28% we can expect from the inverted L. However I believe the 3/8 configuration is adding more horizontal polarization as a trade off for better efficiency which is fine if your interests are more in line for closer in contacts. I don’t see any major signal loss on close in stations but the inv L definitely shows it’s worth beyond 800 or so miles, (whose counting ?) as compared to a 165 ft. flattop at 60 ft.
5: If you build it, I offer the following insights from my experiment. Going the raised radial route is the only way I could consider this or any vertical design with my rocky conditions, your mileage may vary, but read up on them. If you do use raised radials make every effort to run the feed line away at a right angle if possible, mine isn’t. As mentioned, a 1 to 1 current balun is a big MUST; it will reduce any stray induced current on the coax shield.
My MFJ analyzer indicated 40 ohms resistance and about 1.2 to 1 swr. Anything way above or below that number should tell you that your ground plane is inadequate or you have common mode current problems. To achieve your best match, prune the horizontal section length.
Lastly, the hard part, try to make the vertical section as tall as possible and if you are concerned with a DC path to ground while using elevated radials, throw a choke between the coax shield and the ground rod or equivalent. Do not just hookup the coax shield directly, unless you like talking to worms.
FINAL FINAL COMMENTS:
The setup as laid out in this article is working than better than expected and has reawakened my appreciation for the challenge and fun to be found on the 160 meter band. It is noisy at times here in upstate NY with my backyard surrounded by commercial businesses and transformers for the extended care facility 100 ft away, (there, but for the grace of God go I) so I use my flattop 40 as a backup receive antenna when it gets too annoying.
Try it out, the inverted L is as cheap as it gets and will give you a horizontal and vertical sky wave easily matched to coax. Definitely more entertaining than the Lifetime Channel!
Don’t forget; 160 meters separates the men from the boys, see you there!
Tnx for reading,
Bob, N4JTE