Hi Friends:
Welcome to Tech-Talk. This is a series of articles that has appeared in my newsletters for the past several years. Until now, it has been available only to subscribers of the newsletter. I've decided to make it available to anyone who cares to read it.
My aim is to simplify some often complex topics to give you the information you need in an understandable format. I'll state right up front that I have no formal electronics training; nor was I born knowing all this stuff! When I was first licensed in 1989, I knew almost nothing about antennas, feedine, SWR, decibels, or DC Power. What follows are things I've learned by experimentation and observation, along with a good bit or reading.
These articles, and this entire site, are Copyright Quicksilver Radio. Please feel free to link to it, but please do not copy and paste it into other Web Sites.
Thanks and 73,
John Bee N1GNV
2. What is SWR?
Tech-Talk
Part 1
Hi friends,
As promised, here's the first installment in a series of discussions on SWR, antennas, feedlines, and related topics.
My aim is to give you some solid information based on facts, and to dispel some of the myths, old wives' tales, and just plain bunkum I hear regularly on the air and at Hamfests. No heavy-duty theory, and I'll keep the math to an absolute minimum. Some of the topics we'll explore include:
Part 1
Hi friends,
As promised, here's the first installment in a series of discussions on SWR, antennas, feedlines, and related topics.
My aim is to give you some solid information based on facts, and to dispel some of the myths, old wives' tales, and just plain bunkum I hear regularly on the air and at Hamfests. No heavy-duty theory, and I'll keep the math to an absolute minimum. Some of the topics we'll explore include:
3. You Can Tune an Antenna, But You Can't Tuna Fish
Tech-Talk
Part 2
Welcome Back!
Last month we talked about what SWR is. This month we'll explore why we care about it, and what we do about it. If you need to refresh, or are new to the list, previous installments are located below this one.
Modern transmitters are designed to operate into a 50-Ohm resistive impedance. We use 50-Ohm coax, a 50-Ohm antenna, all of our power radiates, and the transmitter is happy. But when the load is something other than 50 Ohms (in other words, the SWR is greater than 1:1, problems can arise. If the mismatch is bad enough, our solid state final amplifier stage can easily overheat and self-destruct. So our radios include a protection circuit that lowers the output power as SWR increases. The circuit generally kicks in at somewhere between 1.5:1 and 2:1 SWR.
So how do we lower the SWR and regain full output power? There are several ways.
Part 2
Welcome Back!
Last month we talked about what SWR is. This month we'll explore why we care about it, and what we do about it. If you need to refresh, or are new to the list, previous installments are located below this one.
Modern transmitters are designed to operate into a 50-Ohm resistive impedance. We use 50-Ohm coax, a 50-Ohm antenna, all of our power radiates, and the transmitter is happy. But when the load is something other than 50 Ohms (in other words, the SWR is greater than 1:1, problems can arise. If the mismatch is bad enough, our solid state final amplifier stage can easily overheat and self-destruct. So our radios include a protection circuit that lowers the output power as SWR increases. The circuit generally kicks in at somewhere between 1.5:1 and 2:1 SWR.
So how do we lower the SWR and regain full output power? There are several ways.
4. SWR Meters Can Make You Stupid
Tech-Talk
Part 3
Welcome to Part 3 of our discussion.
As promised, this month I have some rather eye-popping information for you. We're going to see why your SWR meter can lie to you. Or as another fellow says, "SWR meters make you stupid."
The material in this section was prepared using 2 programs from the ARRL Antenna Book CD. Roy Lewallen, W7EL's EZ-NEC antenna modeling program was used to get the basic antenna data. That info was fed into Dean Straw N6BV's Transmission Line for Windows (TLW) analysis program. If you like to play with antennas, both programs are great tools.
Using EZ-NEC, I "built" a 40 meter dipole at about 33 feet high. As expected, the SWR was about 1.6:1 at the center of the band and below 2:1 at the band edges. Then I opened TLW, specified 100' of RG-8X coax as the feedline and added the feedpoint impedance (77 -j13) calculated by EZ-NEC. TLW calculated the total loss in the coax as just under 1 dB. Most of that was the inherent ("matched line") loss in the coax. The slight SWR mismatch added just a 10th of a dB to the total. None of this was surprising; it's basic antenna theory. But read on...
Part 3
Welcome to Part 3 of our discussion.
As promised, this month I have some rather eye-popping information for you. We're going to see why your SWR meter can lie to you. Or as another fellow says, "SWR meters make you stupid."
The material in this section was prepared using 2 programs from the ARRL Antenna Book CD. Roy Lewallen, W7EL's EZ-NEC antenna modeling program was used to get the basic antenna data. That info was fed into Dean Straw N6BV's Transmission Line for Windows (TLW) analysis program. If you like to play with antennas, both programs are great tools.
Using EZ-NEC, I "built" a 40 meter dipole at about 33 feet high. As expected, the SWR was about 1.6:1 at the center of the band and below 2:1 at the band edges. Then I opened TLW, specified 100' of RG-8X coax as the feedline and added the feedpoint impedance (77 -j13) calculated by EZ-NEC. TLW calculated the total loss in the coax as just under 1 dB. Most of that was the inherent ("matched line") loss in the coax. The slight SWR mismatch added just a 10th of a dB to the total. None of this was surprising; it's basic antenna theory. But read on...
5. Ladder Go, Boys
Welcome to Part 4 of our discussion.
In Part 3, we discussed the advantages of using ladder line to greatly reduce feedline loss. You can reread it if you like, just below this section.
Using ladder line does come with a few challenges, however. Unlike coax, it cannot be coiled, run on the ground, or buried, without paying a price in performance. And most importantly, it does not like to be near other conductive objects. Ladder line is -- in theory, at least -- a balanced feedline. That means that the currents in each conductor at any given point are equal in magnitude (voltage) but 180 degrees out of phase. When that happens, the RF fields in each leg cancel each other out, and the line does not radiate. That's generally what we want. But...
In Part 3, we discussed the advantages of using ladder line to greatly reduce feedline loss. You can reread it if you like, just below this section.
Using ladder line does come with a few challenges, however. Unlike coax, it cannot be coiled, run on the ground, or buried, without paying a price in performance. And most importantly, it does not like to be near other conductive objects. Ladder line is -- in theory, at least -- a balanced feedline. That means that the currents in each conductor at any given point are equal in magnitude (voltage) but 180 degrees out of phase. When that happens, the RF fields in each leg cancel each other out, and the line does not radiate. That's generally what we want. But...
6. Losing Our Balance
Tech-Talk
Part 5
Welcome to Part 5 of our discussion.
In Part 4, we talked about practical installation of ladder line. You'll find that section (and all of the other parts) right below this one.
This month, we're going to take a first look at baluns -- what they do, why they are (sometimes) needed, and perhaps most importantly, how to pronounce "balun" so you don't sound like a lid.
Very simply, baluns match a balanced antenna -- like any typical dipole or loop -- to an unbalanced feedline, most often coax cable. Hence the name: BAL (as in balanced) + un (as in unbalanced) = BAL-un. Not "BAY-lin". "Not buh-LOON". BAL (rhymes with Hal and Sal) un (pronounced like the "en" in fallen. Now you know.
Okay, what do we mean by a balanced antenna?
Part 5
Welcome to Part 5 of our discussion.
In Part 4, we talked about practical installation of ladder line. You'll find that section (and all of the other parts) right below this one.
This month, we're going to take a first look at baluns -- what they do, why they are (sometimes) needed, and perhaps most importantly, how to pronounce "balun" so you don't sound like a lid.
Very simply, baluns match a balanced antenna -- like any typical dipole or loop -- to an unbalanced feedline, most often coax cable. Hence the name: BAL (as in balanced) + un (as in unbalanced) = BAL-un. Not "BAY-lin". "Not buh-LOON". BAL (rhymes with Hal and Sal) un (pronounced like the "en" in fallen. Now you know.
Okay, what do we mean by a balanced antenna?
7. And Regaining It
Tech-Talk
Part 6
Welcome to Part 6 of our discussion.
Last time, we started to look at Baluns. Recall that their purpose is to help to match a balanced antenna (like a dipole) to an unbalanced feed line (like coax). They do this by choking off RF current trying to flow down the outside of the coax shield, forcing equal and opposite currents to flow on the center conductor and the inside of the shield. Baluns can be easy to make...
Part 6
Welcome to Part 6 of our discussion.
Last time, we started to look at Baluns. Recall that their purpose is to help to match a balanced antenna (like a dipole) to an unbalanced feed line (like coax). They do this by choking off RF current trying to flow down the outside of the coax shield, forcing equal and opposite currents to flow on the center conductor and the inside of the shield. Baluns can be easy to make...
8. More Unbalanced Ravings
Tech-Talk
Part 7
Welcome to Part 7 of our discussion.
I was going to start talking about coax this time, but I received two questions from readers that I think bear answering here.
Rich from Connecticut asked "If my coax is 50 Ohm, and I'm connecting it to 450 Ohm ladder line, doesn't that mean I should use a 9:1 Balun? Back a long time ago when I was in school, 50 x 9 = 450, and I don't think that's changed". His math is correct, but...
Part 7
Welcome to Part 7 of our discussion.
I was going to start talking about coax this time, but I received two questions from readers that I think bear answering here.
Rich from Connecticut asked "If my coax is 50 Ohm, and I'm connecting it to 450 Ohm ladder line, doesn't that mean I should use a 9:1 Balun? Back a long time ago when I was in school, 50 x 9 = 450, and I don't think that's changed". His math is correct, but...
9. "Coax"-ing the Best Performance
Tech-Talk
Part 8
Welcome to Part 8 of our discussion.
We've talked quite a bit about ladder line over the past several months. And it certainly has its advantages, in many cases. However, a lot of folks prefer the simplicity of coaxial cable ("coax") and to be sure, 99.99% of modern radios have a coax connector for the antenna. So we'll take some time discussing coax -- what's available, and what are the advantages/disadvantages of each.
As with most things, selecting the proper coax means balancing several often conflicting factors. The most significant are size/weight, loss, cost, and convenience. Other considerations are power handling, flexibility, and the type of installation. Here are some things to consider...
Part 8
Welcome to Part 8 of our discussion.
We've talked quite a bit about ladder line over the past several months. And it certainly has its advantages, in many cases. However, a lot of folks prefer the simplicity of coaxial cable ("coax") and to be sure, 99.99% of modern radios have a coax connector for the antenna. So we'll take some time discussing coax -- what's available, and what are the advantages/disadvantages of each.
As with most things, selecting the proper coax means balancing several often conflicting factors. The most significant are size/weight, loss, cost, and convenience. Other considerations are power handling, flexibility, and the type of installation. Here are some things to consider...
10. The Death of Ham Radio?
(not exactly) Tech-Talk
Part 9
Welcome to Part 9 of our discussion.
This month I'm taking a break from the Technical discussion. I have some thoughts to share that I hope you will find interesting and useful... or at least, thought-provoking.
I think most of us have heard some old-timer whining about the death of Hamfests, and Ham Radio in general.
Don't you believe it, my friends! Here's why....
Part 9
Welcome to Part 9 of our discussion.
This month I'm taking a break from the Technical discussion. I have some thoughts to share that I hope you will find interesting and useful... or at least, thought-provoking.
I think most of us have heard some old-timer whining about the death of Hamfests, and Ham Radio in general.
Don't you believe it, my friends! Here's why....
11. dBeeze and 73eeze? Geeze!!
Tech-Talk
Part 10
Welcome to Part 10 of our discussion.
We'll talk a little more about Coaxial Transmission Line, aka Coax Cable.
This month's topic is prompted in part by another reader's question.
Bubba-Joe, WE1LID asks:
"My SWR's were really high, about 1.5:1. One of the old-timers in the club suggested injecting my coax with something he called DiHydrogen Monoxide (DHMO). He mentioned that it's hard to find, but that he had some on hand that he could sell to me at a good price. I bought a quart jar of it from him for $10. Following his instructions, I carefully injected it into my coax at 1-foot intervals. Like magic, my SWR's disappeared. But now I'm having trouble hearing signals. I bought an amplifier, but that didn't help. What do you think is wrong with my radio?
73's, Bubba-Joe, WE1LID
Well Bubba-Joe, you've managed to roll quite a few mistakes into one question. Let me help you out here...
Part 10
Welcome to Part 10 of our discussion.
We'll talk a little more about Coaxial Transmission Line, aka Coax Cable.
This month's topic is prompted in part by another reader's question.
Bubba-Joe, WE1LID asks:
"My SWR's were really high, about 1.5:1. One of the old-timers in the club suggested injecting my coax with something he called DiHydrogen Monoxide (DHMO). He mentioned that it's hard to find, but that he had some on hand that he could sell to me at a good price. I bought a quart jar of it from him for $10. Following his instructions, I carefully injected it into my coax at 1-foot intervals. Like magic, my SWR's disappeared. But now I'm having trouble hearing signals. I bought an amplifier, but that didn't help. What do you think is wrong with my radio?
73's, Bubba-Joe, WE1LID
Well Bubba-Joe, you've managed to roll quite a few mistakes into one question. Let me help you out here...
12. Aunt Tenna Says
Tech-Talk
Part 11
Welcome to Part 11 of our discussion.
We're going to begin taking a look at antennas. I don't think there's any subject in Ham radio that's more controversial. Nor is there any one so cloaked in mystery, misinformation, magic, miracles, and more. Here are some hard and fast facts about antennas. Always keep these in mind...
Part 11
Welcome to Part 11 of our discussion.
We're going to begin taking a look at antennas. I don't think there's any subject in Ham radio that's more controversial. Nor is there any one so cloaked in mystery, misinformation, magic, miracles, and more. Here are some hard and fast facts about antennas. Always keep these in mind...
13. Wire, Wire, Everywhere
Tech-Talk
Part 12
Welcome to Part 12 of our discussion.
Last time we started to look at simple dipole antennas. Again, here's the picture we've all seen in the Antenna Book and other publications:
14. Let's Get Vertical
Tech-Talk
Part 13
Welcome to Part 13 of our discussion.
We've been looking at one of the very basic antennas -- the 1/2 wave horizontal dipole. This time we'll look at its cousin, the 1/4 wave vertical. You've no doubt seen a picture very similar to this one:
Part 13
Welcome to Part 13 of our discussion.
We've been looking at one of the very basic antennas -- the 1/2 wave horizontal dipole. This time we'll look at its cousin, the 1/4 wave vertical. You've no doubt seen a picture very similar to this one:
15. Get Outta Here!
Tech-Talk
Part 14
Welcome to Part 14 of our series.
Last time we started looking at vertical antennas. This month we're going to continue in that vein, with an emphasis on antennas for hand-held radios (commonly called HTs, or Handie-Talkies). Just about every ham owns one or more. Most often they are either single band for 2 Meters, or dual-band with 70 CM added. And they're quite convenient, allowing us to walk around the house or easily move into the car or office and keep in touch. There are a few drawbacks, however. First, most HTs put out at best a 5 Watt signal. That's plenty if you're close to the repeater or other stations you want to work. But as the distance grows, our signal becomes harder for others to copy. Second, those cute little antennas are terribly inefficient. It's a simple matter of physics and a trade-off in order to have something small, light, and portable. And third, we then compound the problem by operating inside of a car or a building where our signal gets blocked by the metal car body, aluminum house siding, or other things. Take a look at these three diagrams:
Part 14
Welcome to Part 14 of our series.
Last time we started looking at vertical antennas. This month we're going to continue in that vein, with an emphasis on antennas for hand-held radios (commonly called HTs, or Handie-Talkies). Just about every ham owns one or more. Most often they are either single band for 2 Meters, or dual-band with 70 CM added. And they're quite convenient, allowing us to walk around the house or easily move into the car or office and keep in touch. There are a few drawbacks, however. First, most HTs put out at best a 5 Watt signal. That's plenty if you're close to the repeater or other stations you want to work. But as the distance grows, our signal becomes harder for others to copy. Second, those cute little antennas are terribly inefficient. It's a simple matter of physics and a trade-off in order to have something small, light, and portable. And third, we then compound the problem by operating inside of a car or a building where our signal gets blocked by the metal car body, aluminum house siding, or other things. Take a look at these three diagrams:
16. Power to the People
Tech-Talk
Part 15
Welcome to Part 15 of our series.
Well, I've been rambling on about antennas, feedline, and related topics for quite a while. I'm going to depart from that for now, but I'll get back to it. I've noticed that quite a few folks have questions about DC Power and wiring, so we'll spend some time exploring that topic. I'll try to boil things down so that you can get an idea of the considerations and arrive at appropriate choices. Standard disclaimer -- I'm not an electrical engineer. I'll probably over-simplify and over-generalize, and some of my thoughts may not be "Mil-Spec" or exactly by the book. Nit-picking, whining, and carping will be ignored; but if I make a major error I'd appreciate hearing about it.
And the number one question about DC Power I get at Hamfests and online is...
Part 15
Welcome to Part 15 of our series.
Well, I've been rambling on about antennas, feedline, and related topics for quite a while. I'm going to depart from that for now, but I'll get back to it. I've noticed that quite a few folks have questions about DC Power and wiring, so we'll spend some time exploring that topic. I'll try to boil things down so that you can get an idea of the considerations and arrive at appropriate choices. Standard disclaimer -- I'm not an electrical engineer. I'll probably over-simplify and over-generalize, and some of my thoughts may not be "Mil-Spec" or exactly by the book. Nit-picking, whining, and carping will be ignored; but if I make a major error I'd appreciate hearing about it.
And the number one question about DC Power I get at Hamfests and online is...
17. More Power to You
Tech-Talk
Part 16
Welcome to Part 16 of our series.
I should have started this series on DC Power by mentioning the three cardinal safety rules for any wiring project.
1. Make sure you put a fuse as close as possible to the power source.
Remember that any wire between the power source and the fuse is unprotected. If a short circuit develops, the power supply or battery will pump out all the current it can, as long as the circuit exists. When the wire finally melts, the current will cease to flow -- but by then, chances are good that something will be on fire!
Something that a lot of folks don't realize is that the primary function of the fuse is to protect the wiring, not the equipment. If your device malfunctions and starts to draw too much current, it takes a comparatively long time (possibly a second or two) for the fuse to blow. An overheating electronic component can fry itself in just a few milliseconds.
Last time, we started looking at DC Power in the shack. Let's work through a practical example to determine size wire is needed.
Part 16
Welcome to Part 16 of our series.
I should have started this series on DC Power by mentioning the three cardinal safety rules for any wiring project.
1. Make sure you put a fuse as close as possible to the power source.
2. Make sure you put a fuse as close as possible to the power source.
3. Make sure you put a fuse as close as possible to the power source.
Remember that any wire between the power source and the fuse is unprotected. If a short circuit develops, the power supply or battery will pump out all the current it can, as long as the circuit exists. When the wire finally melts, the current will cease to flow -- but by then, chances are good that something will be on fire!
Something that a lot of folks don't realize is that the primary function of the fuse is to protect the wiring, not the equipment. If your device malfunctions and starts to draw too much current, it takes a comparatively long time (possibly a second or two) for the fuse to blow. An overheating electronic component can fry itself in just a few milliseconds.
Last time, we started looking at DC Power in the shack. Let's work through a practical example to determine size wire is needed.
18. Lights Out!
Part 17
Welcome to part 17 of our series.
We've been talking about DC Power, and I ran across a challenge recently that I thought I'd share with you, along with one possible solution. If nothing else, it may get you thinking about a handy gadget you can build to enhance your own shack.
My young assistant Gary recently bought a car that does not have a "you left the headlights on" alert. Since he likes to drive with the lights on during the day -- that's good -- he's been getting a lot of practice with jumper cables -- that's bad. He asked me if I could think of a way to add a warning circuit to remind him to shut off the lights. After doodling through some rather complex ideas involving voltage comparators and the like, I hit on this simple scheme. Even better, all the parts were available at my local Radio Shack. They might even be in your "collection of stuff I can't throw away because I might use it someday". More commonly called the junk box.
You'll need a normally closed 12V relay (or a double throw relay), a small piezo buzzer, and a diode. Pretty much any diode will do, like the popular 1n4xxx series, for example.
Here's how to build it, and how it works:
Take 12V from the headlight circuit -- either the wire that feeds the lights, or if you can get at it, the wire from the headlight switch to ground. It needs to be a wire that's energized only when the lights are on. Connect that to the positive (red) wire on the buzzer. Connect the buzzer's black wire to one of the relay's normally closed terminals. Connect the other relay terminal to ground. Verify that when the headlights are turned on, the buzzer sounds; and of course, does not sound when they are off!
Next, locate and tap a wire that is only energized when the ignition key is in the on or "run" position. Connect this to one terminal of the relay coil, and connect the other coil terminal to ground. Finally, connect the diode across the coil terminals, being careful to observe polarity as shown -- the band on one end of the diode should connect to the positive side of the coil. You could enclose the assembly in a small plastic container, like a pill bottle; or otherwise make sure that there are no exposed terminals. For added safety, you should add fuses to both wires, especially if you run them through the firewall.
When the ignition is on, the relay coil is energized and the relay is held open, silencing the buzzer. When the ignition is off, the relay closes and -- if the lights are on -- the buzzer will sound. The diode protects the rest of the system from the inductive "kickback" generated when the relay coil's magnetic field collapses after power is removed.
It's not exactly cutting edge "rocket surgery," but I hope it gets you thinking about simple things you can build for your mobile, portable, or home station.
That's it for this month. Next time, we'll continue looking at DC Power in the shack.
73 for now
John Bee, N1GNV
Quicksilver Radio Products
Welcome to part 17 of our series.
We've been talking about DC Power, and I ran across a challenge recently that I thought I'd share with you, along with one possible solution. If nothing else, it may get you thinking about a handy gadget you can build to enhance your own shack.
My young assistant Gary recently bought a car that does not have a "you left the headlights on" alert. Since he likes to drive with the lights on during the day -- that's good -- he's been getting a lot of practice with jumper cables -- that's bad. He asked me if I could think of a way to add a warning circuit to remind him to shut off the lights. After doodling through some rather complex ideas involving voltage comparators and the like, I hit on this simple scheme. Even better, all the parts were available at my local Radio Shack. They might even be in your "collection of stuff I can't throw away because I might use it someday". More commonly called the junk box.
You'll need a normally closed 12V relay (or a double throw relay), a small piezo buzzer, and a diode. Pretty much any diode will do, like the popular 1n4xxx series, for example.
Here's how to build it, and how it works:
Take 12V from the headlight circuit -- either the wire that feeds the lights, or if you can get at it, the wire from the headlight switch to ground. It needs to be a wire that's energized only when the lights are on. Connect that to the positive (red) wire on the buzzer. Connect the buzzer's black wire to one of the relay's normally closed terminals. Connect the other relay terminal to ground. Verify that when the headlights are turned on, the buzzer sounds; and of course, does not sound when they are off!
Next, locate and tap a wire that is only energized when the ignition key is in the on or "run" position. Connect this to one terminal of the relay coil, and connect the other coil terminal to ground. Finally, connect the diode across the coil terminals, being careful to observe polarity as shown -- the band on one end of the diode should connect to the positive side of the coil. You could enclose the assembly in a small plastic container, like a pill bottle; or otherwise make sure that there are no exposed terminals. For added safety, you should add fuses to both wires, especially if you run them through the firewall.
When the ignition is on, the relay coil is energized and the relay is held open, silencing the buzzer. When the ignition is off, the relay closes and -- if the lights are on -- the buzzer will sound. The diode protects the rest of the system from the inductive "kickback" generated when the relay coil's magnetic field collapses after power is removed.
It's not exactly cutting edge "rocket surgery," but I hope it gets you thinking about simple things you can build for your mobile, portable, or home station.
That's it for this month. Next time, we'll continue looking at DC Power in the shack.
73 for now
John Bee, N1GNV
Quicksilver Radio Products
19. Hit the Road, Jack
Tech-Talk
Part 18
Welcome to part 18 of our series.
Back to DC Power in the shack. This month we'll take a look at the "shack-on-wheels". The basics of powering the radio don't change when you install a rig in your car, but there are some additional considerations that you need to take into account. First and foremost, the three most important rules take on added importance in a mobile installation, so I'll repeat them here for you:
1 Make sure you put a fuse as close as possible to the power source.
Wiring in the car is subject to chafing, vibration, and possible stresses that are not typically encountered at home.
A "Car-B-Que" can really ruin your day! Don't take chances, don't take shortcuts.
Part 18
Welcome to part 18 of our series.
Back to DC Power in the shack. This month we'll take a look at the "shack-on-wheels". The basics of powering the radio don't change when you install a rig in your car, but there are some additional considerations that you need to take into account. First and foremost, the three most important rules take on added importance in a mobile installation, so I'll repeat them here for you:
1 Make sure you put a fuse as close as possible to the power source.
2. Make sure you put a fuse as close as possible to the power source.
3. Make sure you put a fuse as close as possible to the power source.
Wiring in the car is subject to chafing, vibration, and possible stresses that are not typically encountered at home.
A "Car-B-Que" can really ruin your day! Don't take chances, don't take shortcuts.
20. Double Double, Fuse is Trouble
We're rewriting this section completely with better information and pictures.
Please come back soon.
Until then, here's some good background information:
http://www.w8ji.com/mobile_ground.htm
21. Count Yer Amps, Champs
Tech-Talk
Part 19
Welcome to part 19 of our series.
This time, we're going to take a look at how we can measure high current without having to use the heavy gauge wire necessary for so many Amps. That's the magic of a meter shunt. Here's how it works...
22. I'm a travelin' Man
Tech-Talk
Part 20
Welcome to part 20 of our series.
I'm going to take a little side trip here. Many, if not most of us, have some type of "go-kit" for portable Ham Radio Operation. If you've been subscribed to my newsletter for even a short time, you know that I travel quite a bit to attend Hamfests all over the East Coast and Midwest. I can be on the road for a week or more, even up to a month or more -- when you live in New England, spending all of February in Florida is a pretty good deal! So I get to stay quite a few nights in hotels every year. I need to keep connected while traveling, and my laptop bag has developed into a second go-kit of sorts. While you may not travel as much as I do, you may find yourself on the road for vacations, business trips, family visits, or a trip to a major Hamfest like The Dayton Hamvention. Here are some items I keep in my laptop bag....
Part 20
Welcome to part 20 of our series.
I'm going to take a little side trip here. Many, if not most of us, have some type of "go-kit" for portable Ham Radio Operation. If you've been subscribed to my newsletter for even a short time, you know that I travel quite a bit to attend Hamfests all over the East Coast and Midwest. I can be on the road for a week or more, even up to a month or more -- when you live in New England, spending all of February in Florida is a pretty good deal! So I get to stay quite a few nights in hotels every year. I need to keep connected while traveling, and my laptop bag has developed into a second go-kit of sorts. While you may not travel as much as I do, you may find yourself on the road for vacations, business trips, family visits, or a trip to a major Hamfest like The Dayton Hamvention. Here are some items I keep in my laptop bag....
23. Goin' Batty
Tech-Talk
Part 21
Welcome to part 21 of our series.
We've been talking about DC Power. When we're home, we generally use power supplies that convert house current (110V AC in the US) to the nominal 12V DC that our radios require. But when we're operating portable, whether for fun, emergency and public service communications, or even "at-home portable" when the lights go out, we turn to battery power. Let's find out a little more about batteries....
Part 21
Welcome to part 21 of our series.
We've been talking about DC Power. When we're home, we generally use power supplies that convert house current (110V AC in the US) to the nominal 12V DC that our radios require. But when we're operating portable, whether for fun, emergency and public service communications, or even "at-home portable" when the lights go out, we turn to battery power. Let's find out a little more about batteries....
24. Th-Th-Th-That's All, Volts
Tech-Talk
Part 22
Welcome to part 22 of our series.
Last month we started looking at batteries. If you want to operate your radio using battery power, one of the first questions you need to ask is "What size battery do I need?" With some real world examples, I'll help you to figure that out....
Part 22
Welcome to part 22 of our series.
Last month we started looking at batteries. If you want to operate your radio using battery power, one of the first questions you need to ask is "What size battery do I need?" With some real world examples, I'll help you to figure that out....
25. Head Fer The Hills
Tech-Talk
Part 23
Welcome to part 23 of our series
We're going to take a little detour this month. With Field Day coming up at the end of June, I thought I'd share a few related thoughts. We've been talking lately about DC power, with an emphasis on portable/emergency/temporary operation. That sort of defines the purpose of Field Day, doesn't it? And earlier in the series, we talked about SWR, antennas, feedline, and related topics. For most entry classes, you'll need to install a temporary antenna for the weekend. So you might want to review the whole series of articles, tarting from the top.
Keep in mind -- as always, Safety First!! And here we go...
Part 23
Welcome to part 23 of our series
We're going to take a little detour this month. With Field Day coming up at the end of June, I thought I'd share a few related thoughts. We've been talking lately about DC power, with an emphasis on portable/emergency/temporary operation. That sort of defines the purpose of Field Day, doesn't it? And earlier in the series, we talked about SWR, antennas, feedline, and related topics. For most entry classes, you'll need to install a temporary antenna for the weekend. So you might want to review the whole series of articles, tarting from the top.
Keep in mind -- as always, Safety First!! And here we go...
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