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
Saturday, April 16, 2011
I’ve been using a G5RV antenna for years. It was damaged in a windstorm recently. ..
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
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?
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
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?
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
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 ...
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
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 ...
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
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
Friday, April 15, 2011
I have a problem with my dualband (VHF/UHF) mobile FM transceiver ...
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
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’?
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
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?
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
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
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