The Doctor is In New Ham Companion

I have a question about the term ‘meter’ as it relates to the various labels used for amateur bands..

2016-07-19T09:19:00.001+07:00

Q John asks, “I’ve just started studying for my Technician license and I have a question about the term ‘meter’ as it relates to the various labels used for amateur bands. Does the ‘meter’ of a given band correspond to the wavelength of the frequency of that band?”

A Not necessarily. When you’re discussing Amateur Radio frequency bands, consider their metric labels in broad terms only. This will be easier to understand once you know the historical background. However, let’s start by defining a “meter” in terms of wavelength.

To convert wavelength to frequency, the speed of light is used, as it is also the speed of radio waves. In metric, this is 300 million meters per second. So the conversion formula is:
F(MHz) = 300/wavelength

conversely,
wavelength = 300/F(MHz)

So, 6 meters is really 50 MHz; 2 meters is actually 150 MHz and 70 centimeters (0.7 meters) is 428 MHz. Notice that the frequency that corresponds to 2 meters is well above what hams consider to be “2 meters.”

While some folks would like to have the bands named more accurately (2 meters would be 2.1 meters, for example), tradition
runs deep in this hobby and the majority feel this tradition should be preserved.

In this day of computer-controlled rigs, it is easy to forget that radio technology was once crude indeed. Before the advent of vacuum tubes, there was no such thing as an amplifying oscillator with feedback to control it. Radio signals were generated via a spark gap.

Anyone who has listened to an AM broadcast radio when a thunderstorm is approaching knows that sparks generate wideband RF. The lightning discharges will create bursts of RF that cover the entire AM band. Thus it was in the early days of radio—transmissions were made by spark and the best one could do to limit the output bandwidth was to use an output filter made of a couple of inductors and capacitors along with a narrow-bandwidth antenna. This determined what “band” you were on and you could hear everyone else on the same band at the same time.

Yes, it was bedlam after a fashion, but the range you could work was quite short (a couple hundred miles was “DX”) and there were far fewer operators then. The label for a particular band was broadly interpreted because the signals themselves were broad—and that legacy remains today. That’s why we have a “20-meter band” at 14 MHz even though the true frequency equivalent of 20 meters is 15 MHz!

From QST June 2001

When a beam antenna such as a Yagi or quad produces ...

2016-07-19T09:15:00.002+07:00

Q George, VE3LTU, asks, “When a beam antenna such as a Yagi or quad produces a major radiation lobe at, say, 35º, would the radiation angle be improved by tilting the boom 20º toward the Earth? Would the radiation angle with respect to the Earth now be 15º, resulting in improved DX performance?”

A The short answer is “no.” An array as you describe has its major lobe aimed directly along the boom (0º elevation) when it is in free space. When ground is considered, it increases the elevation of the lobe. Therefore, it is the relation of the antenna to ground (height)
that determines take-off angle.

We can look at it another way. The radiation pattern of an antenna is a summation of the radiation each of many antenna segments as they interact with each other and the ground below
the antenna.

We can visualize the result by imagining a mirror image of the antenna below the ground surface by a depth equal to the antenna’s height above the ground. Thus, as we tip the antenna boom downward, the imaginary boom tips upward to counter it—we achieve nothing.

From QST June 2001

I have two low pass filters. If I put them both in series ...

2016-07-19T09:09:00.003+07:00

Q George, AD5CQ, asks, “I have two low pass filters. If I put them both in series with my transmission line, will I get more reduction of harmonics or would the input losses be excessive?”

A The answers are “yes” and “maybe” respectively.

The amount of loss would be double that of a single filter, but depending upon the filter design, it may be acceptable. I have seen filters with insertion losses as low as 0.25 dB and a 0.5-dB total loss would be quite acceptable to most folks. The best way to check is to put a power meter in line after the filter. A 1-dB loss is about 21 W out of 100.

If you don’t have an external power meter, you can check the difference in receive signal strength. Find a strong steady signal like WWV or W1AW and try switching the filters in and out of line to see how much the S-meter changes.

A 1-dB change would be just about noticeable in terms of meter movement (it’s about 1/6 of an S-unit by the old Collins standard—not that any modern rigs follow the standard, but it should be in the ballpark).

From QST June 2001

I am currently running a Yaesu FT-901 transceiver ...

2016-07-19T09:04:00.003+07:00

Q John, N9QC, asks, “I am currently running a Yaesu FT-901 transceiver with a Cushcraft triband Yagi antenna. I’m considering adding a long-wire antenna for 80 and 160 meters and upgrading to a more modern transceiver. Do you think the automatic antenna tuners included with many of today’s rigs would work for both antennas?”

A Most of the auto tuners incorporated into new rigs have limited tuning ranges. They’ll only deal with SWRs up to about 3:1. That may be sufficient to extend your ability to use your tribander beyond its 2:1 SWR bandwidth on each band. Don’t count on the built-in tuner having enough range to handle the long-wire, though. You will need a separate, wide-range tuner to load your long-wire.

From QST June 2001

Can you offer some tips on chasing radioteletype (RTTY) DX?

2016-07-17T14:35:00.001+07:00

Q Can you offer some tips on chasing radioteletype
(RTTY) DX?

A Glad to! Like any other form of DXing, the quest for RTTY DX
demands patience and skill. When a DXpedition is on the air with RTTY from a rare DXCC entity, your signal will be in competition with thousands of other HF digital operators who want to work the station as badly as you do. Sometimes pure luck is the winning factor, but there are a couple of tricks you can use to tweak the odds in your favor.

Let’s say that you’re tuning through the HF digital subbands one day and you stumble across a screaming mass of RTTY signals. On your computer screen you see that everyone seems to be frantically calling a DX station. Oh, boy! It’s a pileup!

You can’t actually hear the DX station that has everyone so excited, but what the heck, you’ll activate your transceiver and throw your call sign into the fray, right? Wrong!

Never transmit even a microwatt of RF until you can copy the DX station. Tossing your call sign in blindly is pointless and will only add to the pandemonium. Instead, take a deep breath and wait. When the calls subside, can you see text from the DX station on your screen? If not, the station is probably too weak for you to work (don’t even bother), or he may be working “split.” More about that in a moment.

If you can copy the DX station, watch the exchange carefully.
Is he calling for certain stations only? In other words, is he sending instructions such as “North America only”? Calling in direct violation of the DX station’s instructions is a good way to get yourself blacklisted in his log. (No QSL card for you—ever!) Does he just want signal reports, or is he in the mood for brief chats? Most DX stations simply want “599” and possibly your location—period. Don’t give them more than they are asking for. (A DX RTTY station on a rare island doesn’t care what kind of weather you are experiencing at the moment.)

When DX RTTY pileups threaten to spin out of control, many DX operators will resort to working split. In this case, “split” means split frequency. The DX station will transmit on one frequency while listening for calls on another frequency (or range of frequencies).

A good DX operator will announce the fact that he is working split with almost every exchange. That’s why it is so important to listen to a pileup before you throw yourself into the middle. If you tune into a pileup and cannot hear the DX station, tune below the pileup and see if you copy him there. If his signal is strong enough, he shouldn’t be hard to find if he is working split. His signal will seem to be by itself, answering calls that you cannot hear. This is a major clue that a split operation is taking place.

Finally, don’t neglect the other modes if you’re hunting digital DX. An increasing number of DX stations are now using PSK31, so make sure you add that to your list of operating modes.

From QST June 2001

The material in an NPN transistor consists of a positive layer (the base) surrounded by two negative layers...

2016-07-17T14:24:00.003+07:00

Q Ken, KE6ZWN, asks, “The material in an NPN transistor consists of a positive layer (the base) surrounded by two
negative layers (the emitter and collector). How do the manufacturers build transistors so that the current flows correctly
between layers while at the same time keeping them insulated
from each other?”

A See Figure 1. Transistors are made up of layers of material
that are “doped” with impurities so that they are either “P” type (positive charge) or “N” type (negative charge). Now, these charges aren’t quite like the ones in a battery— they exist in the form of an occasional extra electron or positive ion (an atom with an electron deficit) that are available as “current carriers.”

Where two different layers of material touch, an exchange of current carriers takes place and a neutral (or near neutral)
“depletion region” forms (an area where the net charge is depleted).
In a bipolar transistor, the base-emitter junction depletion region is fairly thin, whereas the region between the base and the collector is rather thick.

From QST June 2001

Over the past two years or so, I have received dozens of QSL cards from DX stations ...

2011-10-19T07:44:00.001+07:00

Q Joe, WT7V, asks, “Over the past two years or so, I have received dozens of QSL cards from DX stations that I’ve never worked. In fact, many of these QSLs confirm contacts supposedly made when my rig was completely off the air for weeks at a time. Do you think someone could be bootlegging my call sign?”

A Bootlegging is always a possibility, but it is rare. If the
cards seem to arrive in spurts, there is a more likely explanation.

It is not at all unusual for a call to be consistently misrecorded in contests. For example, K0NS gets several cards per year intended for K0DI, a very active CW contest operator. If you sound out the suffixes of both call signs in Morse, you can understand how someone could blur the two together. Early this year, NT1A inquired about some cards that were apparently meant for our own Dave Patton, NT1N, here at Headquarters. In the heat of a contest, missing or transposing the individual letters is easy to do.

From QST June 2001

What does the ‘dBi’ mean when used to rate an antenna

2011-10-18T22:17:00.002+07:00

Q Jerry, KC8OTH, asks, “What does the ‘dBi’ mean when
used to rate an antenna

A I will presume that you are somewhat familiar with the decibel. If not, at least a few numbers will put it into perspective. Decibel is a term that can compare two powers or voltage levels. The formulas are:

dB = 10log (P1/P2) where P1 and P2 are two power levels.

It can also compare voltages, if the voltages are at the same impedance. The formula is:

dB = 20log (V1/V2) where V1 and V2 are the two voltage levels.

(For “extra credit,” if the resistances are not equal, you can
use the formula dB = 10log ((V12/R1)/(V22/R2)).

Now, in antenna gain, there are two common references. The first is an imaginary antenna called an “isotropic” radiator. This is an antenna that radiates equally in all directions. An isotropic radiator placed at the center of a sphere would illuminate the sphere equally. No such antenna exists in real life. A practical example of what is nearly an isotropic radiator is a light bulb.

When gain is expressed in dBi, it indicates how much louder a signal from that antenna will be in the main beam of the antenna than it would be if the same amount of power were applied to an isotropic radiator in free space. The thing to remember about gain is that an antenna develops gain by concentrating energy in one direction and not radiating energy in other directions. Two examples of gain are flashlights, and the technique of cupping your hands when you shout to make the sound louder in the desired direction.

A directional antenna such as a Yagi can have considerable gain. Typical HF Yagi beams can have 8 dBi gain or more; a large VHF or UHF beam can have 20 dBi gain, or even more. Some easy numbers to remember are:

1 dB = 1.25 × power
2 dB = 1.6 × power
3 dB = 2 × power
10 dB = 10 × power

A 20-dBi-gain antenna would have 10 × 10 or 100 times the power gain of an isotropic radiator. One watt fed into a 20-dBi gain antenna would be as loud as 100 W fed into an isotropic source, but only in the direction the antenna is beaming.

Decibels also work in the other direction, too. An antenna with –3 dBi “gain” actually has a loss of 3 dB—it will lose half of the power applied to it. An antenna that is –10 dBi is radiating 1/10 the signal of one with 0 dBi gain; one that is –20 dBi is radiating 1/100 the signal and so on. A –20 dBi gain antenna with 1 W fed to it would sound as loud as an isotropic antenna being fed with 10 mW

Most H-Ts have antennas that are not very efficient. A gain of –10 dBi would be about typical. This can work very well if you are near a repeater, but if you are right at the edge of a repeater’s range, or operating simplex over a few miles, this will not give a very good signal; it will sound “scratchy” on the receiving end.

Another reference point is dBd, or referring the gain to a half-wave dipole in free space. The half-wave dipole in free space has a gain of 2.15 dBi, so gain expressed in dBd is always 2.15 dB less than gain expressed in dBi. Don’t worry, the gain of the antenna is the same in both cases, only the reference has changed. If you want to compare an antenna whose gain is in dBd to one whose gain is in dBi, add 2.15 to the gain of the antenna in dBd.

I don’t want to make it too complicated, but I will add that most antenna gain figures tell you what the antenna would be if it were in free space—infinitely far away from the Earth. In the real world, the ground affects the antenna performance by reflecting signals upward. This actually adds up to about 5 dB to the gain of an antenna. So, a half-wavelength dipole over ground can actually have about 5 dBd of gain! Slick, eh? The half-wavelength dipole over ground has 5-dB gain over a halfwave dipole in free space.

From QST April 2001

My son wants to run sophisticated gaming software on the computer ...

2011-10-18T22:11:00.002+07:00

Q My current shack PC is a 333-MHz Pentium II with 64 Mbytes of RAM and a 3-Gbyte hard drive. My son wants to run sophisticated gaming software on the computer when I’m not using it, and my wife would like to do a few things on the machine with PhotoShop. I’m considering the idea of pulling the motherboard and replacing it with a new 133-MHz bus board and 1 GHz CPU. Is this the most cost-effective approach?

A Motherboard and CPU prices have been plunging lately, but you’ll still shell out about $600 for a good-quality 1-GHz motherboard/CPU combo. You can probably save more than $100 by purchasing a 933-MHz package. Believe me, you won’t notice the performance differential between 933 MHz and 1 GHz. Clock speed isn’t everything!

motherboard chipset is “old” as far as the PC market is concerned, but I’ve measured it to be as fast, if not faster, than the newer 815E chipset. Go with a 440BX-chipset motherboard and you’ll save a little cash without sacrificing performance.

You might consider expanding your memory to 256 Mbytes to accommodate future needs. Beware of cheap memory, however. You can find 256-Mbyte SDRAM for under $100, but there is memory and there is memory. Bargain-basement memory can drop data when you’re cycling it at 133 MHz on your new motherboard. Just one dropped bit is enough to corrupt data and possibly trigger the dreaded “blue screen of death.” This is the last thing you want to see, say, in the middle of a contest!

Definitely upgrade your hard drive. With drive prices falling through the floor these days, you have no excuse. You can find 30-Gbyte drives for less than $125. Stick with the highspeed (7200 RPM) drives and your programs will load at the speed of thought!

From QST April 2001

I operate slow-scan TV (SSTV) using sound card software.

2011-10-18T22:06:00.005+07:00

Q I operate slow-scan TV (SSTV) using sound card software. Last week I upgraded my PC to the Windows ME operating system and now my SSTV software is acting up. According to what I see on the display, I am grossly overdriving the sound card input. Reducing the LINE INPUT volume control on the sound card mixer helps, but I have to practically take the level to zero (and it is very touchy). Is this a problem with Windows ME?

A In an indirect way, yes. If you did a full installation of
Windows ME (not just an upgrade), chances are it loaded
a Microsoft sound card driver automatically. Depending on the type of sound card you own, the Microsoft driver can cause some strange behavior. If you still have your original sound card software, I suggest that you reinstall the original drivers. If not, go to the Web site of the company that made your sound card and download the drivers from there.

From QST April 2001

I have an HTX-202 hand-held transceiver. I would like to rebuild the battery pack ...

2011-07-07T13:21:00.003+07:00

Q Paul, W5PDA, asks “I have an HTX-202 hand-held transceiver. I would like to rebuild the battery pack, but
I’m not sure how to go about doing it. Can you give me some
advice?”

A Speaking as one who has rebuilt several battery packs (mostly for laptops), I have to caution against attempting it unless you have no other option. (Keep in mind that replacement packs are available from several aftermarket manufacturers. See the ads in this issue of QST.) If you choose to go ahead, proceed with caution.

The pack was assembled in such a way as to prevent disassembly. In order to disassemble it, you have to break it—there’s just no way around this. However, if you are very careful, you can break it in such a way that reassembling the pack is still possible, and with a reasonable appearance to boot. Start by studying the pack carefully. Try to figure out what holds it together. Come up with an idea of how to take it apart, then try to come up with reasons why that won’t work very well. When you have an idea with the least “won’t work” reasons, that’s the one you should use.

Once you have the case apart, the rest is fairly easy. You will find multiple NiCd cells connected together with thin metal strips, usually spot-welded to the cells. Your next task is to find cells of the same size (typically nonstandard, but usually obtainable—try Digi-Key for one source). There is a caveat here: the original cells were probably matched according to their charge and discharge characteristics. If you buy unmatched cells, you won’t get as much use from a rebuilt pack because you’ll have the “weakest link in the chain” effect.

Once you have the replacement cells in hand, you have to connect them together in some fashion. You can do this with wire and solder, or you can use the original strips if you can yank them off the old packs without cutting yourself (been there...).

To solder the wire or strips to the new batteries is a difficult
task because solder doesn’t like to stick to stainless steel or shiny aluminum (which is what most new batteries use as contact plates). First, warm up your soldering iron to its maximum temperature (if you have a 300-W iron, use it, although 60 W will do). Sandpaper or file the contacts on the new batteries to rough them up a bit so that the solder has a place to stick. Take your iron and heat the contact plate up as quickly as possible— a 3-second or longer “dwell” time will probably damage the battery, so keep it shorter than that. Apply solder to the contact to make sure it sticks. Once you get the solder to stick to the contact, add your wire/metal strip and “reflow” the solder.

Of course, when you do this, you also have to make sure that: (1) the new cells go together with the exact alignment of the old cells and (2) that the solder you added doesn’t cause the resulting pack to be too big to fit back in the old case.

Assuming you are able to connect all of the cells in a way that allows them to fit in the battery pack case, you’ll have to find a way to get the pack back together (glue, small screws, etc).

If this sounds like a lot of work, that’s because it is, but it is the cheapest way to get close to your original pack capacity. There is a much cheaper and easier alternative, but the price is in time per charge. Buy a battery case for the rig (made for alkalines) and just put NiCds in it. The capacity (and possibly the voltage) will be less than your original pack, but it is definitely a cheap and sweat-free alternative.

From QST April 2001

I’m just getting started with the HF digital modes, but I’ve run into trouble already...

2011-07-07T13:08:00.004+07:00

Q I’m just getting started with the HF digital modes, but I’ve run into trouble already. The “help” file in one of the software packages I recently downloaded from a source in Europe suggested an operating frequency on 160 meters between 1.838 and 1.840 MHz. I tried this and quickly discovered— the hard way—that I was in the middle of the 160-meter CW DX window. Was the software programmer mistaken in his choice of suggested frequencies?

A For the IARU Region in which he lives, I’m sure his suggestions make perfect sense. For amateurs living in Region 2 (North and South America), it will cause no end of headaches. See the ITU/IARU map in Figure 1.

Figure 1—ITU zone/IARU region map. The IARU regions are
bordered in black.

You’ll find a comprehensive chart of IARU Region
bandplans on the Web at www.iaru-r2.org/p11e.htm. The
chart is too large to publish here, but let’s take a look at just
the 160-meter portion.

As you can see, on 160 meters in Region 1 the recommended digital segment is 1838-1840, so 1838 is okay in that part of the world. For hams in Region 2, however, 1830-1840 is for intercontinental operating only. Routine domestic operation is 1800-1830, so Region 2 digital operators should be lower in the band. It pays to remember that our world is host to a diversity of bandplans; what works in one location may not be appropriate in another. When in doubt, double check.

From QST April 2001

The V terminals are reading +5 volts. What are the S terminals for?

2011-04-16T09:28:00.000+07:00

Q Clayton, KE4RTM, asks, “I have a simple question regarding a 5-V Lambda power supply. On the output side there are –S and –V, ground, and +S and +V terminals. The V terminals are reading +5 volts. What are the S terminals for?”

A On a power supply with +/–V and +/–S terminals, the S terminals are very likely “sense” inputs. In circumstances where the current draw might cause a significant voltage drop in the cable you are using to connect the power supply to the load, you would connect the sense terminals to the load via separate wires. The sense terminals would read the voltage at the load and relay that information back to the regulator circuit. If the voltage at the load drops, the sense circuit detects this and adjusts the output of the supply to a higher voltage so that the voltage on the load comes back up to the proper supply voltage.

Because there is very little current draw in the sense circuit itself, the wires connecting the S terminals to the load can be small gauge, even if the wires that supply power from the V terminals are quite large.

For many applications, the voltage drop is not so critical, so the manufacturer often includes shorting bars that connect the V and S terminals together at the supply.

From QST March 2001

I’ve been using a G5RV antenna for years. It was damaged in a windstorm recently. ..

2011-04-16T09:25:00.001+07:00

Q I’ve been using a G5RV antenna for years. It was damaged in a windstorm recently. It broke where the ladder line connects to the dipole. Can this be easily repaired, or should I just break down and buy another antenna?

A This is a minor repair. Clean the areas to be reconnected using sandpaper, emery cloth or steel wool until the metal is shiny. Make a good mechanical connection depending on where the break is and how it connects. If there is an eye for the wire to go through, loop the wire and twist it tight. If you are connecting wire to wire, twist the wires together so that they make a strong connection. Solder the connection using rosin flux solder.

Soldering outdoors can be difficult because any cool breeze keeps the connection from getting hot enough to melt the solder. Either use a torch, or bring the antenna indoors for this repair.

From QST March 2001

When shopping for radios, I keep seeing the terms WARC and MARS. Can you elaborate?

2011-04-16T09:20:00.002+07:00

Q Craig, KC8POE, asks, “I am a new ham and I am studying
for my General license. When shopping for radios, I keep seeing the terms WARC and MARS. Can you elaborate? What are they, and do I use them when using my radios?”

A WARC stands for World Administrative Radio Conference. These are the folks (meeting in Geneva, Switzerland) who allocate radio frequencies. At the 1979 WARC they gave Amateur Radio three additional HF bands:

30-meters: 10,100-10,150 kHz
17-meters: 18,068-18,168 kHz
12-meters: 24,890-24,990 kHz

To this day, many hams call them the WARC bands. Amateur radio gear made before 1979 was not capable of operating in these new bands. Almost all modern radios, however, offer these bands as standard features.

MARS stands for Military Affiliate Radio System. This is an organization that runs traffic nets on designated frequencies just above or below most Amateur Radio bands. MARS stations also run phone patches from troops overseas. This was very popular during the Viet Nam and Gulf Wars. Most MARS members are volunteers that make their time and stations available, although there are some MARS stations on US military bases.

Most radios in the past were manufactured so that the tuning circuits would work slightly above and below the amateur bands, allowing them to run on MARS frequencies.

Today’s solid state transceivers are capable of operating across the whole HF spectrum and are locked out by the microprocessor from operating outside the amateur bands. A procedure must be performed to “open up” the MARS frequencies. Military personnel at a military installation may operate using only the MARS license, but civilian volunteers must have an Amateur Radio license and a MARS authorization and special call sign for use on MARS frequencies.

From QST March 2001

Would an antenna tuner improve the match and make the antenna work better?

2011-04-16T09:14:00.002+07:00

Q Ray, K4YDI, asks, “I have just put up a used vertical antenna. I’m not getting the SWR I want (1.5:1 or less). Would an antenna tuner improve the match and make the antenna work better?”

A Unfortunately, you did not mention what SWR you are
seeing now. An antenna tuner may bring your SWR down
to 1:1, but if your SWR is already under 2:1, it is not necessary.

Remember that an antenna tuner doesn’t tune the antenna it only matches the impedance shown at the station end of the coax to that of the transceiver. Your transceiver is probably capable of delivering its full output at the 2:1 SWR, so a sufficient portion of your RF output is already reaching the antenna.

Whether your antenna radiates most of that power depends on the physical characteristics of the antenna and its associated ground system, not the impedance seen by the transmitter.

To improve the radiation of a vertical, make sure you have
a good ground/radial system. Don’t rely on a single ground
rod driven into the soil. Try stringing out as many radial wires
as you can by just laying the wires directly on the ground the more the better and connecting them together at your antenna’s ground point. Your SWR may not be reduced (it may even rise), but I’m willing to bet that your antenna will “play” better. If you find this to be the case, then you can worry about burying the wires to keep them out of harm’s way.

From QST March 2001

I have always worked CW, until I went mobile. Because I drive a stick shift, it is hard to do CW while driving the hills ...

2011-04-16T09:09:00.002+07:00

Q I have always worked CW, until I went mobile. Because I drive a stick shift, it is hard to do CW while driving the hills of Pennsylvania (although it can be done). I thought that I would give SSB a chance, but I am having trouble tuning the signals for clarity. I think I am not tuning properly because I have difficulty getting a signal that I can understand, and when I do, I turn out to be way off their receive frequency. Can you give me some pointers?

A The best tuning of an SSB signal is accomplished by tuning from the high pitch to the low. I’ll explain. As you know, on 160, 80, and 40 meters, lower sideband is used and on the higher bands, upper sideband is the norm. Let’s use 20 meters as an example.

Set your rig for 20-meters and upper sideband. Tune down to the lower end of the 20-meter phone band (14.150 MHz) and slowly tune up in frequency. You will soon hear a highpitched squeaky voice. Keep tuning slowly and you will hear the pitch become lower and lower. Soon it will become intelligible, but still too high. Keep on tuning up and the voice will eventually sound natural. There, you’ve done it!

If you continue tuning up, the voice will become lower and lower until it sounds like a 45 RPM record played at 33 RPM, then it will become unintelligible again.

On the bands that use lower sideband, the process is reversed. You start at the upper portion of the band and tune down slowly. The voices will go from the squeaky down to intelligible speech.

From QST March 2001

I have a Cushcraft AR-270 Dual Band (2-meter/70-cm) Ringo antenna mounted on the side of my house ...

2011-04-16T09:05:00.001+07:00

Q I have a Cushcraft AR-270 Dual Band (2-meter/70-cm) Ringo antenna mounted on the side of my house. I changed its location the other day and checked the SWR after installing coax. It now reads 5:1. I changed coax, checked it again and the SWR is still 5:1. I have checked all connections and everything seems in good shape. What’s next?

A By any chance, when you relocated the antenna, did you mount it near (within 6 feet or so) anything metal of a significant size? If so, the Ringo is probably “coupling” to this and changing the antenna’s resonance as a result. If not, there may have been something internal to the antenna that broke when you moved it.

From QST March 2001

I have a problem with my dualband (VHF/UHF) mobile FM transceiver ...

2011-04-15T15:54:00.004+07:00

Q Juan, KB3CJG, asks, “I have a problem with my dualband (VHF/UHF) mobile FM transceiver, a Yaesu FT-8100. When I install it in my car I cannot transmit. The voltage of my car battery appears to be a bit low (around 12 V, as reported by the rig’s built-in voltmeter) and the FT-8100 manual recommends 13.8 V. I have no problem operating at home using a 13.8 V power supply. How can I solve this problem?”

A It sounds like you have a bad battery, voltage regulator or alternator, or a “partial short” (a low resistance that shouldn’t be there) in your automotive electrical system.

Take your car to a mechanic and have your battery system
checked with your rig disconnected. If there is a problem, such as the battery not holding a charge, or a faulty alternator, get it fixed. My guess is that the mechanic will find a problem.

However, if everything is okay, then disconnect the automobile cables from the fully charged battery. Connect your rig to the battery and see if it operates. This will tell you if you have a “partial short” in the car.

If all of the above are good, then make sure that you have a good direct connection from your rig to the battery (no substitutes such as the fuse block or cigarette lighter!).

From QST March 2001

I presently hold a Technician license, but I can listen with my TS-430S transceiver. Can you suggest a few HF ‘hot spots’?

2011-04-15T15:44:00.003+07:00

Q John, KD5JUP, asks, “I’m a new ham and I was wondering if you could suggest some active HF bands that I might monitor to get a sense of what goes on there. I presently hold a Technician license, but I can listen with my TS-430S transceiver. Can you suggest a few HF ‘hot spots’?”

A A frequency chart is a good tool for new hams. One is available for download and printing from the ARRLWeb at www.arrl.org/field/regulations/bands.html. Or, you may request one by sending an SASE to:

ARRL
Field and Education Services
225 Main St
Newington, CT 06111
…and ask for the US Amateur Band Chart.

The key to capturing hams on the air is knowing which bands are open, and therefore in use, at what times of the day and year.

For the most part, 20 meters (14.000-14.350 MHz) is open from early morning to late evening all year around and is a “round-the-world” band—the best place to hear DX (foreign) stations. You should be able to turn your radio on and tune between 14.000 and 14.060 MHz and hear CW; and 14.150 and 14.350 and hear SSB just about any time from 8 AM to 8 PM Local, almost 365 days a year.

Eighty meters is a “local” band and is populated in the early morning (before folks go to work) and early to late evening, but the band is more active in the winter than in the summer. Summer produces electrical storms that emit static that can be heard for hundreds of miles. The upper portion of the phone sub-band (3.850-4.000 MHz) is densely populated with conversations on all sorts of topics. A plus is that on this band you can almost always hear both sides of the conversation.

Forty meters is a 24-hour-a-day band. It is good out to about 300 miles during the day and worldwide at night. CW is fun all the time on this band, but foreign broadcast stations start to creep into the phone portion in late afternoon and into wee hours of the morning.

Fifteen meters often has activity in the daytime, but it tends
to fall off in the evening. The same is true of 17 meters.

Ten meters is a different animal. It is greatly affected by
the solar cycle. A good place to look for activity is in the phone portion between 28.400 and 28.500 MHz. Since we’re presently at the peak of a solar cycle, 10 meters will open almost every day from early morning to evening. At the bottom of the cycle (probably around the year 2005), 10-meter band openings will not be as common.

From QST March 2001

Please clarify for me the difference between a radial and counterpoise. Aren’t they basically the same?

2011-04-15T15:36:00.002+07:00

Q Lou, KB6JLI, asks, “While reading an advertisement for a vertical antenna, I noticed the ad mentioned that no radials are needed, but it also says that you need to use an 80- foot counterpoise. Please clarify for me the difference between a radial and counterpoise. Aren’t they basically the same?”

A The difference between the terms “radial” and “counterpoise” is subtle, but significant. Radials usually consist of multiple bare wires either buried in, or laid upon, the ground and are not tuned to a specific frequency. Such wires don’t really show a resonance because they are coupled so heavily to the lossy Earth. Their purpose is solely to reduce ground losses (very good information on this topic can be found in the 19th edition of The ARRL Antenna Book, starting on page 6-24).

A counterpoise is a wire or group of wires mounted close to ground, but insulated from ground, to form a low-impedance, high-capacitance path to ground. The purpose of a counterpoise is to provide an RF ground for the antenna.

From QST March 2001

I have an old Swan TB-3HA tribander beam antenna. How can I check and recondition the traps? ...

2010-11-01T14:39:00.001+07:00

Q Ray, WA3CLD, asks, “I have an old Swan TB-3HA
tribander beam antenna. How can I check and recondition
the traps? It has 4 driven-element traps, 2 director traps
and no reflector traps. Can I adapt one of the driven element
pairs of traps for the reflector?”

A The biggest problem with old traps is corrosion, both ex ternal and internal. To “recondition” them, you’ll have to take them apart and thoroughly clean the inside. You can check a trap for internal corrosion without taking it apart by putting an ohmmeter across it—the resistance should be a relatively low value. If it is over 100 Ω, you probably have a corrosion problem.

Traps are designed to present a high impedance at the
“trapped” frequency and to act as a loading coil at lower frequencies, so you should indeed be able to use driven element traps for the reflector by adjusting the tubing lengths slightly.

If you have an antenna analyzer or a dip meter, you can check the resonance of just the reflector (it should be about 5% lower than the driven) by assembling it as a unit. You may need to get it at least 10 feet up in the air, however, because the effect of the nearby ground detunes a low antenna, changing the resonant point from where it will be when the antenna is installed later.

From QST February 2001

I’d like to try microwave operating from home, but I can’t put up antennas outdoors...

2010-11-01T14:32:00.004+07:00

Q I’d like to try microwave operating from home, but I can’t put up antennas outdoors. Is it possible to at least receive microwave signals with an attic antenna? Will the signals make it through a standard shingled roof? I’m thinking specifically of receiving satellite microwave downlinks. Bob Bruninga, WB4APR, answered this question with an interesting experiment:

A “Since I have a Direct-TV 1-meter dish on a tripod that I
use for demonstrations, I decided to check its performance through various materials. The unit has a bargraph signalstrength meter for use during alignment. The meter scale goes from 0 to 100. Here are the results:

Outdoors in the clear: 92
1/4-inch plywood covering: 80
7/16-inch plywood covering: 77
3/4-inch plywood: 60
3/4-inch Masonite: 70
3/4-inch stack of paper: 60
1.5 inches of plywood: 43

(Note that the signal drops out completely at 35.)
“I have no idea if the scale is at all linear or logarithmic, and my arm was too short to both hold the wood and see the monitor well. So, your mileage may vary.

“With digital the picture is always perfect. You don’t lose any quality until it drops out completely. Of course, most of this margin is needed in case of rain. But it looks to me like it should be possible to receive microwave downlinks through a simple 3/4-inch roof and shingles, as long as rain, ice or snow are not involved.”

From QST February 2001

What is a switching type power supply ...

2010-11-01T14:28:00.002+07:00

Q Keith, KF4BXT, asks, “What is a switching type power supply and what type is typically used and/or recommended for running a station? I think most of us, by now, understand that our power supplies should be regulated and filtered, but are there reasonable ways to add regulation and filtering to those that don’t already have it?”

A In a linear power supply, the line voltage goes directly into a low-frequency transformer where it is stepped down to the appropriate low voltage before rectification, filtering and regulation. In a switching power supply, the line voltage is directly rectified and filtered to produce a high dc voltage. This voltage is then “switched” at a high frequency rate (not RF, but certainly higher than audio—perhaps 50 kHz, for example) by switching transistors. It is then fed into a high-frequency transformer and the output is rectified and filtered. Regulation can be done in the output stage, but more typically, the regulation is done at the switching transistor to allow the amount of energy fed to the transformer to be adjusted as needed.

One advantage of the switching technique is that higher frequency components are much smaller and lighter weight for the same power capability than their low frequency counterparts. Another advantage is that, since the transformer is the least efficient part of the supply, controlling its input power (as is done in a switching power supply) can provide much better efficiency. The power lost as heat in a linear supply is typically 40-60% of the output power. In a switching supply, that typically drops to 10-20%.

The disadvantages of a switching supply are the increased complexity (more likelihood of a component failure), increased cost (many more parts) and tendency to create radiated RF (the switching waveform is usually pretty close to a square wave, so it contains a lot of harmonics). This last item has been the main one that has kept switching supplies out of the ham market until recently. Current designs use an extensive amount of filtering and radiation suppression techniques to greatly reduce unwanted RF.

Adding filtering and regulation to a linear supply is a simple
matter. Information on calculating filter component values for a particular desired ripple can be found in The ARRL Handbook chapter on power supplies. However, regulation will come at a cost in reduced output capacity—if you have an unregulated supply that puts out 15 V, you probably won’t be able to get more than 13 V from a regulator system attached to it.

All switching supplies have some kind of regulation, although some designs are quite crude and could use improvement. I don’t suggest trying to modify a switching supply unless you have studied switching power supply design extensively.

From February 2001

What is wrong with operating FM simplex between 145.8 and 146 MHz? ...

2010-10-29T08:39:00.002+07:00

Q What is wrong with operating FM simplex between 145.8 and 146 MHz? I hardly ever hear signals in that part of the band.

A This touches on the issue of voluntary band planning, which was addressed in “Washington Mailbox” in the December 2000 QST. You might want to take a look at that column.

The problem with operating in the 145.8 to 146 MHz segment is that the amateur satellite community uses this portion of the spectrum. There are several FM repeater satellites that operate with uplinks in this segment. If you’re chatting with a local friend on 145.85 MHz, for example, there is a chance that OSCAR 27 will hear you and relay your conversation over thousands of miles without you even realizing it! The FM satellites are crowded already, so they don’t need “unintentional signals.” Other SSB and digital satellites have uplinks here as well, and your signals could make it impossible for these birds to hear the signals intended for them.

SO-35 and AO-10 have downlinks in this portion of the band. These signals are often weak and your terrestrial FM QSOs will obliterate them.

Just because you can’t hear the satellite signals, doesn’t mean that they are not there. With the typical FM setup, you’re not likely to hear satellites in this portion of 2 meters at all.

Voluntary band planning allows everyone to enjoy Amateur Radio in all of its various forms, but it only works if we all respect the plans. It isn’t so much a legal issue as it is one of common courtesy.

From QST February 2001