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Amateur Myths
Alan Applegate (K0BG)
on
July 8, 2008
View comments about this article!
There's a television program called Mythbusters® that has made a name for itself, by exposing popular urban myths. Some of the crews' antics seem far-fetched, but generally the conclusions are rather close to home. They're usually entertaining, and sometimes quite amusing.
Amateur radio has its myths too. Unfortunately, there isn't a television program aimed at dispelling them. One thing is for sure, the myriad of postings here on eham.net sure haven't dispelled them! I say this because, you continually see the same ones cropping up over and over again.
What follows is just the tip of the iceberg, and I've chosen them only for their frequency (pun intended) of appearance here on eham.net. While based in fact, a lot of neophytes and old timers alike will affront them, but that just means they're biased; a fact that will become evident soon enough.
Probably the single, most prevalent myth within these pages deals with the much-aligned G5RV, doublet antenna. As designed by Jim Varney (SK), the antenna was intended to operate on 20 meters, yet be usable on 40 and 80, preferably with an antenna tuner, yet have a reasonable radiation pattern and SWR. It fulfills its mission quite well. The myth parts are; there wasn't a shortened (junior) version, and it was not designed as an all-band antenna. Yes, of course, you can stick a big antenna tuner in front of it, and load it up on most (not all) of the HF bands, but the efficiency suffers, and the radiation pattern stinks. Adding some confusion was the fact, that early versions (there were several) had a BALUN. Apparently, after thinking about it, he (G5RV) wrote other articles wherein he admonished its use.
Speaking of the lowly BALUN... It should always be printed in caps as it is an acronym for BALanced/UNbalanced. It is, in the strictest of terms, a transmission line transformer. Without getting into a whole bunch of discussion, there are two basic types; a voltage BALUN, and a current BALUN. Typically (not always) these are listed as 4:1 and 1:1. In the former case, it could also be a 1:4. Remember, it is a transformer, and its primary and secondary windings may be reversed. Quite obviously, there is a lot more to BALUNs than this over-simplified description. The myth part is, few folks know which one to use in any given situation. This may take me out on a limb with the purists, but if the input to the BALUN is from an antenna tuner (built in as part of it or not), the correct choice is a 1:1 current BALUN.
Another BALUN myth deals with whether one should be used, or not. If it was strictly necessary, our forefathers would have never gotten on the air! In some cases, a choke BALUN made from coiled-up coaxial cable will suffice, but even that isn't necessary if the feed line is perpendicular to the plane of the antenna. Yes, there will be some imbalance, and the pattern could be a bit skewed. However, assuming a BALUN will suddenly correct a poor radiation pattern, a lousy SWR, or a specific RFI issue, is a myth!
Antennas, no matter what they are made of, or what frequency they operate on, follow a given set of known parameters. There is nothing mythical about them. The laws governing their operation have long since be laid down by the likes of Kirchhoff, Maxwell, and many others. What is mythical is the hype which runs rampant through the amateur radio marketing community. This includes exaggerated gain figures, superfluous efficiency ratings, obscene power handling capabilities, and super-low radiation angles. It's bad enough that antenna manufacturers resort to such ham-fisted (I just couldn't help myself with this pun) behavior, far too many of us believe it! If you doubt this, then why is it that too-many amateurs believe that a low SWR, or the number of DX contacts you can make on any given antenna are marks of merit? Talk about mythology!
Over the years, quite a few amateur radio manufacturers have come and gone. Drake, Gonset, Heathkit, and Swan come to mind, but there have been many others to be sure. Some vintage hardware (like the Drake R4C, with a few minor modifications) are still a formidable performers when compared to today's lineup. Speaking of which, the real bottom line is, there isn't much difference between the most expensive units on the market, and the midline priced ones. The reason is, the vast majority of the time band noise is the limiting factor. The more expensive units do sport more features, obviously, and some of those might allow a QSO to take place when a lessor radio would not. However, when you're comparing similarly priced radios, the major difference is in the eyes of the beholder! This is why it amuses me reading the responses to the proverbial question, which radio should I buy? The correct answer is always the same; buy the one which suits you, your operating style, your budget, and perhaps your fancy. Assuming you'll get the right answer by asking someone else for their opinion, is a myth!
Lord knows there are many more myths. Unfortunately, a lot of neophyte amateurs are going to get hurt, financially if not physically, by believing in myths. The key in knowing what is, and what isn't a myth, is education, not someone's opinion. Education wise, arguably, one of the best bargains in amateur radio is the ARRL Handbook. If you read it a couple of times cover-to-cover, you'll know more than 90% of the active amateurs, and that's no myth!
Alan, KØBG
www.k0bg.com
This article has expired. No more comments may be added.
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Amateur Myths
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by W5WSS on July 8, 2008
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Well said! Lb Cebik and others have helped, your self included. We are a diverse group of people and with that comes their many different levels of involvement to this hobby. A dipole is a very efficient antenna when operated where it is hmmm BALANCED ummm that actually qualifies it as a dipole, but when used beyond which it then becomes a doublet.And if left as is the transfer of electromagnetic energy in either direction receive or transmitting faces leading or lagging the following pulses of the transmitter, or re-radiated rf lost to space that the receiver could not absorb. There really is nothing better from any stretch of the imagination than resonance that which only the dipole can naturally claim...Doublets offer their service like the g5rv,but from a resonance standard can not equal The dipole. Tuning an antenna to resonance could be synonymous with engine timing. When done correctly the work is measured in horse power that is standardized, and so it goes for the dipole I made this analogy to point out this simple truth, unless someone has gone to great lengths, ie a test range with an anechoic chamber and controlled testing that which is beyond the scope of most hams, they can not possibly be objective with respect to an antennas functions! I hear the ham say this antenna is the greatest or that one is the greatest yet it is relative only to the extent of random skywave and time variation as it pertains to how their antenna responded at that instant..I have seen so many times when antenna A responds better than antenna B while rapidly switching between them...But one truth that I always appreciate most... a dipole is perfect! Otherwise its a doublet g5rv. Regards W5WSS
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Some More Amateur Myths
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by TANAKASAN on July 8, 2008
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1) An antenna with a 1:1 SWR is a perfect antenna.
2) Turning the microphone gain to full and shouting at the microphone will get you the DX.
3) Every amateur radio station needs a linear amplifier.
4) A DSP in the final I.F. will fix a poor receiver.
Tanakasan
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RE: Amateur Myths
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by G3RZP on July 8, 2008
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G5RV was Louis Varney, not Jim Varney. He and his XYL, Nelida, stayed with me a few times. The original G5RV was fed with balanced open wire line.
Antennas need not be resonant to radiate perfectly well, despite the myths in amateur radio about resonance and antennas. Incidentally, what is meant by a 'resonant antenna'? In amateur circles, it usually means one with a low SWR However, a free space dipole fed with 50 ohm coax will have 1.5:1 SWR, and depending on the coax length, a reactive component. A better definition is that an antenna is resonant when the feed point impedance is resistive. But then, the terminated rhombic is a good example of a non-resonant antenna showing a substantially resistive feedpoint. As far as dipoles are concerned, the Hertzian dipole (0.05 wavelength long) has a gain of 1.76dB over an isotropic radiator, while a half wave dipole has a gain of 2.16dBi. See some of the professional antenna books.
Where non -resonant antennas can have a problem is that the feed impedance is complex with quite possibly a high reactive component. It is in the impedance transformation to give the transmitter its optimum load impedance that the losses appear, especially when it's something like 10-j400 or worse (e.g. a 16 foot unloaded whip at 2MHz, as used to be fairly common in marine radio)
Where something like a T, gamma, or omega match is used, resonant antennas have the advantage that a somewhat wider bandwidth is available for any particular SWR limit than with a non-resonant antenna.
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Amateur Myths
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by AH6GI on July 8, 2008
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Great article.
The reality is that the antenna and lowly feedline count for more than the radio.
Band conditions and local noise from computers and appliances count for more than the radio.
Local grounding conditions, angle to the horizon, topology count for more than the radio.
Then there's the skill of the operator...
So what's this about the radio? Hardly counts at all.
Something like an old Drake 2B paired with a Heathkit SB-401 will outperform the newest and bestest, given a better antenna, lower local noise, and better QTH.
de ah6gi/4
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RE: Amateur Myths
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by N3EF on July 8, 2008
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Myth: At HF, a PL259 has a loss of .1db
Fact: At HF, a PL259 has a loss of less than .009db
Eric N3EF
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Amateur Myths
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by K6YE on July 8, 2008
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Alan,
Congrats on a great article!
There are still people who will argue about what is "the best" antenna, transceiver, etc. Your answer rings true in that is an individual decision or opinion. Other material such as BALUN, UNUNs, etc. just require research and a more than basic understanding of transmission theory and practice.
Keep up the good work.
Semper Fi,
Tommy - K6YE
DX IS
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RE: Amateur Myths
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by VA3DXV on July 8, 2008
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I read as far as "Jim Varney" and couldn't get the thoughts of "Ernest goes to Camp" out of my head. I had to stop. KnoWhutImean, Vern?
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RE: Amateur Myths
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by W9OY on July 8, 2008
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Yet another myth
"The reality is that the antenna and lowly feedline count for more than the radio."
How about "open wire can't be used near anything metal.."
How about "the more radials the better" or "you need at least 60" or "evenly spaced"
How about: "you need to cadweld the ground wires to your radio or the NEC police will get you and the insurance won't pay"
another myth: "the insurance will pay." Those jokers get paid not to pay.
How about "Voltage fed antennas are hard to make work"
How about "don't buy an amplifier what you need is a better antenna!!!!"
How about "You have to be a really good operator to run QRP" The reality is the guy listening to your puny signal is the really good operator, not you.
73 W9OY
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RE: Amateur Myths
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by W9OY on July 8, 2008
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Oh yea and the ever faithful
"My dummy load has 1:1 SWR but doesn't radiate worth a darn" Like DUH, what is a dummy load designed to do?
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Amateur Myths
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by AD4U on July 8, 2008
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Great article especially about receivers of today VS those of yesterday. A good operator using a 45 year old vacuum tube Drake 2B receiver will run rings around an average operator using a $10,000 modern DSP receiver.
IMO the most important "things" in a HAM shack are:
1. OPERATOR
2. Antenna
3. Rig
Dick AD4U
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Amateur Myths
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by N3MMH on July 8, 2008
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As usual, another great article Alan.
The most common one I hear around my area is the typical "tuner is tuning on all bands" phrase.
We all know that the tuner just makes the rig happy. The antenna (or lack thereof) on the other hand...
As I try to explain the ERP portion of antenna theory to those people, and the concept leaves me getting blank stares in return.
Cheers & 73
Todd-N3MMH
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RE: Amateur Myths
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by K0BG on July 8, 2008
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I was going to wait until later today, to see just how many folks picked up on the Jim Varney pun. So far two, and one hit it dead on the head. Know what I means vern?
Alan, KØBG
www.k0bg.com
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RE: Amateur Myths
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by W0IPL on July 8, 2008
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[quote]"My dummy load has 1:1 SWR but doesn't radiate worth a darn" Like DUH, what is a dummy load designed to do? - W9OY[/quote]
Or the other side of that "My dummy load doesn't radiate at all."
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RE: Amateur Myths
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by CBISBACK on July 8, 2008
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K0BG Wrote:
Antennas, no matter what they are made of, or what frequency they operate on, follow a given set of known parameters. There is nothing mythical about them. The laws governing their operation have long since be laid down by the likes of Kirchhoff, Maxwell, and many others. What is mythical is the hype which runs rampant through the amateur radio marketing community.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
But what happens if the antenna didn't read, or understand, the laws of Kirchhoff, Maxwell, and many others? What happens if the antenna is a wild duck and doesn't follow the established laws. Why can't the antenna manufacturers just change the laws?
Then anything goes and the new age hams line up to drink from the marketing well.
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RE: Amateur Myths
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by W4LGH on July 8, 2008
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And the myths will continue to grow, as more and more enter the Amateur Radio Game.....
W9OY said.."My dummy load has 1:1 SWR but doesn't radiate worth a darn" Like DUH, what is a dummy load designed to do?"
Let's take this a little farther... your dummy load is 50ohms, resistive, and you get a 1:1 match, but it doesn't radiate well. Why, the energy is being turned into HEAT. Now, let's change out the 50ohm resistive load and install a 1000ohm load. Now let's put our "Wizbang Super-Duper Magic-Box" antenna tuner in from of it, and we can tune it back to 1:1...great right? Now transmit into the load the same amount of time and I will BET you your load does NOT get as hot!!! Why, because the same amount of current is NOT flowing into the load. It is being wasted in your "Wizbang Super-Duper Magic-Box" antenna tuner. This same thing will apply when you change out your dummy load for your antenna! Your tuner may allow you to use this "dummyload" antenna, but it WILL NOT make it radiate any better. Its a simple experiment to do, you should try it and see for yourself.
The Myth that the antenna tuner in the shack will make your antenna radiate effectively is just that, a MYTH. It is a crutch, a band-aid (no-pun intended) that may allow your radio to put out full power, but that full power will never be radiated by your antenna. It will radiate something, and you WILL make contacts, but it simply can NOT DO what most hams think it does.
Another example of this, someone in an earlier post said, "Voltage fed antennas are hard to feed" A good example of a voltage fed antenna is the good ole end-fed 1/2wave antenna. You have a very hi-z at the end of the wire where you are feeding it. It requires a circuit (and you can call it an antenna tuner if you wish) call a matchbox. This will convert the low-z antenna wire to the hi-z feed point, thus converting currect to voltage, and you can feed the antenna perfectly. Now try this with your "Wizbang Super-Duper Magic-Box" antenna tuner in your shack, and see if you can get it to work?? You may see a match, but you are only fooling yourself if you think you are feeding this wire with ANY effeciency, or even at all!
The MATCH has to be at the antenna, NOT in the shack.
Now we'll sit back and wait for the flames...
73 de W4LGH Alan
http://www.w4lgh.com
PS..I have several end-fed voltage 1/2wave antennas and they work very well, but are single band antennas, do to the current to voltage matching network required to feed it at the antenna.
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RE: Amateur Myths
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by WW5AA on July 8, 2008
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Great article Alan. My favorite is "I'm raising my G5RV to 25' tomorrow, what direction should I string it in to work EU on 80 meters?"
73 de Lindy
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RE: Amateur Myths
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by K3WVU on July 8, 2008
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W4LGH makes a good point about the "magic box" in the shack. I have a dipole for another band that also gives me a SWR of about 2:1 on 6M. That doesn't give me full power out, but I've made a lot of contacts with it. If I hit the tune button on my 746PRO and activate the autotuner, it will give me a perfect SWR on 6 and show full power output, but it also makes the antenna go "deaf".
CBISBACK's comments are also true. Go to the reviews section and look at all of the great reviews given to a popular brand of "no radial" vertical antenna. All of the noobs are so excited about the great SWR's they acheived out of the box and how quiet the antenna is.
A "perfect" SWR is no match for resonance.
Good article Alan.
73
Dwight
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RE: Amateur Myths
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by N2EY on July 8, 2008
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Another oft-repeated myth is why hams use LSB below 10 MHz and USB above. The myth is that it derives from early 1950s SSB rigs that used a 9 MHz SSB generator and a 5 MHz VFO.
But if you do the math, it doesn't work that way.
73 de Jim, N2EY
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RE: Amateur Myths
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by WB2WIK on July 8, 2008
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I think my favorite myth is that you can get all the best information available from the internet.
That goes along with, "If it's in print, it must be true."
:-)
WB2WIK/6
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RE: Some More Amateur Myths
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by KA4KOE on July 8, 2008
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1) An antenna with a 1:1 SWR is a perfect antenna.
Dummy loads make FABULOUS ANTENNAS!!!
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Compression vs. Cadweld
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by KA4KOE on July 8, 2008
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How about: "you need to cadweld the ground wires to your radio or the NEC police will get you and the insurance won't pay"
Not true. UL listed compression connectors are also permitted per the NEC. Exothermic welds (Cadweld is a brand name) sometimes problematic and can have a high rate of failure during installation, and must be redone.
Compression connectors must be attached using the appropriate power tool the manufacturer lists for installation.
Exothermically connecting wires to your radio will damage it severely. I'm sure you mean't you need to exothermically weld the grouding conductors to the ground rod(s).
Whatever the case, if you have the electrical installation inspected by the local AHJ, properly permitted, and it meets all applicable codes that the AHJ enforces (NFPA 70 is the national recognized minimum standard of care for installation methods and materials), then you shouldn't have a problem. HOWEVER, that being said, it wouldn't hurt to find out if the insurance company has some freaky WRITTEN guidelines before you peform any work. Knowledge is POWER.
This is where it pays to have a paper trail. If a claim is thrown out arbitrarily, then you should have standing for some sort of recourse.
Of course, I'm an engineer, not a lawyer.
PHILIP
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RE: Amateur Myths
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by W5WSS on July 8, 2008
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G3rzp said "antennas need not be resonant to radiate perfectly well"..? You used the word perfectly,I surely you do not beleive that. Perhaps a better description would be antennas need not be resonant to radiate reasonably well. A doublet is not resonant. and therfore does not qualify to be called a dipole. The point I am making is in the value of the dipole based on its simplicity. myth a doublet is a resonant dipole. regards W5WSS
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RE: Amateur Myths
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by N3JBH on July 8, 2008
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"by K0BG I was going to wait until later today, to see just how many folks picked up on the Jim Varney pun. So far two, and one hit it dead on the head. Know what I means vern?"
Yea Yea nice cover up.
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RE: Amateur Myths
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by AA5JG on July 8, 2008
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"Great article Alan. My favorite is 'I'm raising my G5RV to 25' tomorrow, what direction should I string it in to work EU on 80 meters?'"
Great point! You don't know how many times I hear phrases like this in the local ham community. Guess the idea of 1/2 wavelength in height gets completely lost.
73s John AA5JG
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RE: Amateur Myths
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by AA5JG on July 8, 2008
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How about: "The ARRL cares about their members and does what is in the members' best interest?"
73s John AA5JG
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RE: Amateur Myths
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by W5WSS on July 8, 2008
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Another myth...VERNticals(I could not resist!) pick up more noise than horizontals very debateable.
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Amateur Myths
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by WX4O on July 8, 2008
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I use a 4 to 1 balun between my rig and my ladder line fed multiband (Cobra) dipole. The balun has connectors for the ladder line on the output side and a coax connector on the input side. I don't want to connect the ladder line to my tuner directly since it's a unecessary hassle to connect/disconnect them. I have a short coax 'pigtail' on the rig that is disconnected whenever wx threatens or the rig is turned off. Seems to work fine.
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Amateur Myths
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by W4JBR on July 8, 2008
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Sorry but I can't resist.....
"I always disconnect my antennas during a storm to keep Lightning out of my shack!"
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RE: Amateur Myths
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by K0BG on July 8, 2008
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Actually, Jeff, it wasn't a cover up. The first version correctly named Mr. Varney.
However, one of my good friends was over for a visit as I was working on the article. His comments were: (sic), I think the G5RV was actually designed by Jim Varney, or at least you'd think that by what people say about.
I couldn't resist. After all, puns are fun, and so are double entendres. Life is good!
Alan, KØBG
www.k0bg.com
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Whats in your "antenna wallet"?
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by KC8BYF on July 8, 2008
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MYTH or TRUTH ???
The best antennas are really resonant dipoles at a 1/2 wavelength above average terrain for each band segment an op wants to use. If you're in a pinch for space, though, and can only place one antenna that you'd wish to use on all bands 80 thru 10, which one has been time proven over a many years to yield decent results.
...There is one antenna that has been a favorite here for quite some time. This antenna definitely is not a myth. It really isn't "resonant" on any band but, comes close on 30 and 17 meters as a multi lobed and somewhat high gain antenna, as it will give under a 2:1 SWR and excellent performance with the tuner bypassed in my particular situation. It works pretty good on all bands 80m thru 10 m including the WARC79 bands. In a pinch I have even pressed it into service on 160 meters by terminating the 450 ohm line with the ends connected together, at the base, and tuned it as a single wire feed.
What is this "mysterious antenna" ?
135 foot doublet fed with 42 feet of 450 ohm windowed ladder line. (If you want more height, than 40 or so feet, 77 feet 6 inches of windowed 450 ohm line can be used as well). YES, the length of the ladder line on this particular antenna is critical to it's performance.
Here are several different ways to feed this antenna that all have their limitations yet perform well in different situations.
1) bring the ladder line into the shack and use a balanced tuner (like the old Johnson Match Box). Or there is of course the option to home brew a link coupled balanced tuner.
2) the best way (in my humble opinion)is feeding this arrangement with a remotely tuned ((motorized variable air caps and relays for switching the balun from "in front of" or "behind" the caps depending on what band you're using)) balanced tuner at the base of the 450 ohm line and 50 ohm coax into the shack.
3) a 1:1 balun at the base of the ladder line to an "L" network tuner in the shack.
4) a 1:1 balun at the base of the ladder line and a "T" trans-match arrangement in the shack.
This has been a fun article thread to follow ALAN...
Regards,
jimmie
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RE: Amateur Myths
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by KD2BD on July 8, 2008
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W4LGH wrote:
> Now, let's change out the 50ohm resistive load and install a 1000ohm
> load. Now let's put our "Wizbang Super-Duper Magic-Box" antenna tuner
> in from of it, and we can tune it back to 1:1...great right? Now transmit
> into the load the same amount of time and I will BET you your load
> does NOT get as hot!!! Why, because the same amount of current is
> NOT flowing into the load.
Current flow is only half the story.
Power equals E*I. If the current flowing through a resistor is lowered as a result of increasing its resistance, then the voltage across the resistance must INCREASE in proportion to the decreased current if the power delivered into the load is held constant (through suitable, low-loss impedance matching).
This is the idea behind the basic operation of a simple transformer. If the current is stepped down, then the voltage is proportionally stepped up in the process, while keeping the input and output power levels essentially equal.
An impedance matching network (antenna tuner, coupler, etc.) is a variable RF transformer. It performs an identical function.
> The Myth that the antenna tuner in the shack will make your antenna
> radiate effectively is just that, a MYTH. It is a crutch, a band-aid
> (no-pun intended) that may allow your radio to put out full power,
> but that full power will never be radiated by your antenna.
Not true.
> The MATCH has to be at the antenna, NOT in the shack.
Not true.
> Now we'll sit back and wait for the flames...
Because you know what you are stating is false and has been proven as such in both theory AND practice in the RF profession for many decades.
In other words, troll alert, folks.
As Alan, K0BG, pointed out in the conclusion of his article, "Unfortunately, a lot of neophyte amateurs are going to get hurt, financially if not physically, by believing in myths. The key in knowing what is, and what isn't a myth, is education, NOT someone's opinion."
Well stated!
73, de John, KD2BD
http://kd2bd.ham.org/
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RE: Amateur Myths
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by K5END on July 8, 2008
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Great article!
I think a "myth buster" (R)(C) column (named something other than "mythbuster" to prevent a lawsuit) would be a great feature to have on eham
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RE: Amateur Myths
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by K5END on July 8, 2008
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quote, "my favorite myth is that you can get all the best information available from the internet."
WIK,
That statement is the best mythbusting I've seen to date.
Even if good information is available, and often it is, the problem is that you have to sort it out from the misinformation. :-)
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Amateur Myths
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by KB2DHG on July 8, 2008
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I liked your article and it does bring to point many mythacal points. I went from a great antenna farm in a house to a G5RV in an apartment and the true fact is simple... SPEND ALL THE MONEY ON THE ANTENNA!
With my 3 element beam up on a tower I was able to work the world with 50 watts!
My G5RV although works on most bands does not favor DX!
BUT if you cannot get a beam up or any big antenna then a G5RV will work just don't expect great performance...
So, to me mordern rigs are nice but give me an old rig with a GREAT antenna...
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RE: Amateur Myths
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by N3JBH on July 8, 2008
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I just could not help myself there Alan. Realy it was a great read and many thanks Jeff.
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RE: Amateur Myths
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by W4VR on July 8, 2008
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Here are a few more myths:
1. You absolutely need a tower to support an antenna.
2. Exchanging 5-9 reports for 48 hours straight does not cause brain fog.
3. Use a dummy load to tune your transmitter, then switch to a non-resonant antenna without retuning, will reduce co-channel and adjacent channel interference.
4. The top-of-the-line receiver will give you an improved signal to noise ratio during a thunderstorm.
5. ESSB helps you break a pileup.
6. Breaking into a QSO by saying "contact" or "break break" with no call letters is a good way to make friends.
7. Feeding a balanced antenna (yagi) directly with coax improves your front-to-back.
8. Inverted-L's work as well as verticals.
9. A vertical with one radial will give you a directional pattern.
...etc., etc.....
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RE: Amateur Myths
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by NV2A on July 8, 2008
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good article! Very informative for me.
here's a myth:
Someday, someone will write an antenna book for dummies. One that is not overly wordy but only states the basic facts without a lot of gibberish designed to fill the book with extra pages.
I can't believe the basics of antenna design and workings for ham operators can't be written in pamphlet form. I guess what I'd like to own is some wiz's outline for his antenna book ! :D
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What Would Jim Varney Do?
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by AB0RE on July 8, 2008
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Hi Alan,
Just curious if you've gotten into homebrew balun construction (I'm mainly curious about 1:1 current baluns). If so, can you please let us know what Type of ferrite material you use?
I found the ARRL handbook I have gives just enough information to raise more questions. I found it interesting they recommended a 12 turns on a Type43 ferrite for a 1:1 current balun whereas the W2DU-style baluns use a different value ferrite bead (73 or 77, I believe). I suppose I should bite the bullet and get a balun book but I was hoping you could steer me in the right direction.
73,
Dan / ab0re
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Amateur Myths
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by G0GQK on July 8, 2008
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Regarding baluns, every book that I have read has stated that a 1:1 balun can be used in conjunction with a balanced antenna with a resistance between 50 and 72 ohms fed with 50 0hm coax, so it should only be used with an antenna which is known to have this resistance figure.
The 4:1 balun is used with a dipole fed with 300, 450, or 600 ohm feeders, as with a multiband dipole.This means that a tuner is more able to "tune" the antenna system with a high resistance., eg. 4000 ohms down to 1000 ohms.
The G5RV, which is three half wavelengths on 20 metres was originally fed with a tuned open wire feeder when it was designed by Mr Varney. This antenna also works well on 80 metres. However the antenna's produced by 95% of the makers do not comply with the original design, in those days amateurs operated transmitters which used valves.
A myth which isn't spoken of much of these days was that a piece of wire, known as an antenna, which is tuned to a frequency and becomes resonant by using an ATU doesn't radiate as well as an antenna which has been cut to resonate on that frequency. Been a long time since I've heard fella's argueing for hours about that !
Mel G0GQK
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Amateur Myths
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by KI4WAF on July 8, 2008
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Amen! Great article, Alan!
Here's a few more I'd like to contribute
* Antennas must be "resonant" - If you listen to some of these guys, you'd think that unless you're using a 1/2 wave dipole cut to within one inch of 468/f that your radio is going to explode and your dog's hair is going to be burned off from stray RF.
* You need a "backup rig" - Speaking of a way to waste newcomers' money! Are we doing something that's so important that we have to have a hot spare at all times? No. Most of the time people are just talking about their old radio, but they choose to give it a really important sounding name. New guys read this and think that it is somehow a requirement.
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RE: Amateur Myths
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by KI4WAF on July 8, 2008
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And one more myth I just can't resist:
If you're feeding your antenna with 300 ohm ladder line, you need a 4:1 balun on it (or preferably a 6:1 balun), since any quantity of 300 ohm ladder line will automatically show a 300 ohm impedance regardless of length or the impedance of the antenna on the other end of it :-)
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Amateur Myths
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by G0GQK on July 8, 2008
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Just been looking through some of my antenna design cuttings book, and I'm surprised that a design by G0FAH which was printed in QST in June 1995 has never been heard on the air.
A dipole 94 ft long fed with 41 feet of 450 ohm feeder, into a 1:1 balun and then to 50 ohm coax. The antenna was designed so that it could be used without an antenna tuner and it is cut for CW portion of each band but the SWR figures shouldn't be a great deal different for SSB and the internal tuners of most rigs could bring the antenna into a 1:1 resonance, except for one band.
29.00 Mhz SWR 2:4:1 24.9 mhz SWR 1:5:1 18.1 Mhz SWR 2:1 14.2 Mhz SWR 1:5:1 7.1 Mhz 2:4:1 3.56 Mhz not good with an SWR of 7:6:1
Mel G0GQK
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RE: Amateur Myths
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by W8JI on July 8, 2008
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by W4LGH on July 8, 2008
<<Let's take this a little farther... your dummy load is 50ohms, resistive, and you get a 1:1 match, but it doesn't radiate well. Why, the energy is being turned into HEAT. Now, let's change out the 50ohm resistive load and install a 1000ohm load. Now let's put our "Wizbang Super-Duper Magic-Box" antenna tuner in from of it, and we can tune it back to 1:1...great right? Now transmit into the load the same amount of time and I will BET you your load does NOT get as hot!!!>>
I'm not sure what you are trying to say.
Less some very small loss in the matching network, it will get just as hot when matched with a tuner.
If there is a transmission line between the 1000 ohm load and the matching network the line loss might actually be less with the 1000 ohm load.
So I'm not sure what you are trying to say... maybe it was just worded wrong?
73 Tom
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Amateur Myths
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by N0FPE on July 8, 2008
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Thanks Alan! Always like to read your thoughts and musings! I did however see one comment abt the ARRL...Some folks just dont get it...give it a rest.
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Amateur Myths
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by W6VPS on July 8, 2008
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Well done Alan. As usual good info and food for thought.
John AA5JG
Gee John thanks for sharing you extreme dislike for the ARRL. And your telling us because.....?
Paul/W6VPS
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Amateur Myths
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by KE4ZHN on July 8, 2008
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Myth: Antennas have to be cut to the band to perform, anything else wont work.
Myth: Tuners are evil and to be avoided at all costs.
Myth: Balanced line feeders are horrible and will radiate all over your shack and kill you with RF exposure.
Myth: Coax is the only way to go.
Myth: A doublet is a lousy antenna.
Myth: Baluns are evil and should be avoided at all costs.
Myth: Amplifiers are evil and anyone who uses one should be burned in hell.
Myth: Contesting promotes good amateur practice.
Myth: ESSB doesnt splatter or occupy excessive tx bandwidth.
Myth: Setting the mike gain all the way to the right makes you DX better.
Myth: Breaking into a QSO just for a signal report will make you some new friends.
Myth: Running 5kw and 35 db of processing is legal during a contest.
Myth: Alpha's are the best amplifier in the world.
Myth: To sound good on the air, you need at least 15 gadgets between the mike and the rig.
Myth: The ARRL cares about amateur radio, not just money.
Myth: You need a tower to enjoy amateur radio.
Myth: Rag chewing in the DX window is good amateur practice.
Myth: Tuning up on top of a qso is good amateur practice.
Myth: Arguing and fighting on 14.275 with a mental case up in Canada is good amateur practice.
Myth: Claiming "ownership" of your pet frequency is legal and good amateur practice.
Myth: Hollingsworth actually did something for amateur radio.
Myth: QRP is fun for the guy trying to dig your weak pathetic signal out of the noise.
Myth: running barefoot into your G5RV 10 feet off the ground in mid summer on 75 meters will get you lots of contacts.
Myth: Discussing your health problems on the air is interesting to others.
Myth: Talking about 6 meters while operating on 75 is interesting to others.
Myth: firing up your net 2 kc or less from an ongoing qso is legal and good amateur practice.
Myth: Poking your nose into other amateurs business is good amateur practice and shows your a good person for trying to help. (this one is dedicated to a friend of mine who knows what is meant here)
Myth: Using 000 gauge welding cable will make your antenna a lot more broad banded.
Myth: Taking 20 minutes to load up your amplifier isnt bad for the tubes.
Myth: Using a pulser to tune up saves the tubes. Especially when you take 20 min to tune up.
Myth: Most amateurs are nice people.
Myth: You can always trust a fellow ham when you buy used gear.
Myth: Amateurs never lie or stretch the truth.
One must always be prepared to separate the bovine fecal matter from the truth when dealing with your fellow hams. 73 DE KE4ZHN
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RE: Amateur Myths
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by N3EF on July 8, 2008
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W4LGH Wrote:"The Myth that the antenna tuner in the shack will make your antenna radiate effectively is just that, a MYTH. It is a crutch, a band-aid (no-pun intended) that may allow your radio to put out full power, but that full power will never be radiated by your antenna. It will radiate something, and you WILL make contacts, but it simply can NOT DO what most hams think it does."
You mean all that stuff I read in the book "Reflections II" (Walter Maxwell, W2DU)...the part about the tuner creating a conjugate match that resonates your antenna system...the reflected power from the mismatch at the antenna being re-reflected by the tuner due to the conjugate match over and over til all power is radiated by the antenna except for any losses in the transmission line between tuner and antenna... you mean all that is hooey? Damn, Iv'e been duped again.
Eric N3EF
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Amateur Myths
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by K3DLB on July 8, 2008
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Myth: Hams take showers (or baths) before going to a hamfest.
Myth: Having your wife get a ham license is a smart thing to do.
Myth: Members of the Home Owners Association will approve my antenna because I'm a member of ARES/RACES.
Myth: If I need help on an Interstate Highway, I'll call for assistance on 146.520.
Myth: Chicks dig my mesh hamfest Yaesu hat.
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RE: Amateur Myths
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by W9OY on July 8, 2008
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All antenna books are written for dummy's. If you were a smarty you wouldn't bother reading it
73 W9OY
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RE: Amateur Myths
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by ARRLBOOSTER on July 8, 2008
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Hi, This is Alan's good friend. I know that it was a typo that led to the name given a Jim Varney. Come on Alan, ol buddy, man up to your typo:)
Thanks for the lunch OM!
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Amateur Myths
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by N0IWK on July 8, 2008
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LOL I Didn't Think G5RV could be Jim Varney LOL
Jim Varney (Who is also Deceased as of 2000) Was a Funny man best Known for his Earnest Character.
See Videos of some of Jim Varney's (As Earnest) best Commercial Bloopers here:
http://www.youtube.com/watch?v=C5ED_5eiccE
73 de N0IWK
Kevin Lee Diehl (CNA, CWNA, CWNE, MENSA) N0IWK
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RE: Amateur Myths
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by K0BG on July 8, 2008
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Dan, ABØRE: It depends on the BALUN. I have used a lot of mixes, and if you do them right, mix 61 and 67 work very well for BALUNs. I have used mix 43, but they don't seem to be balanced well, but maybe I didn't give the mix a chance.
I expected Tom, W8JI, to comment on the 1:1 vs. 4:1 BALUN issue, and perhaps he will. The issue isn't the ratio (1:1 or 4:1), it is the design: current vs. voltage which counts.
As I stated above, some purists may object, but the choice for any antenna tuner (coupler, transmatch, etc) is a 1:1 current BALUN. Voltage BALUNs tend to saturate when driven into highly reactive loads, rendering them nearly useless. Properly designed (a misnomer in some cases) 1:1 current BALUN will work very well, over a wide range of frequencies and/or impedances.
Stated another way, to assume a 4:1 (or 1:4) is the correct choice is assuming facts not in evidence. For those who disagree, you need to purchase Dr. Sevick's book. And, I might suggest, you go to http://www.w8ji.com and read what Tom has to say.
A similar myth is floating around the internet with respect to placing the BALUN on the input, rather than the output of a tuner. That doesn't work, and in fact is adds insult to injury.
One last comment about Jim vs. Louis Varney. It wasn't a fully unintentional mistake, albeit it started out that way. As I said, I had company while I was writing the article. My company and I both proofread the article, and he started to chuckle over the (originally incidental) name change. Knowing just how silly "Earnest" was (notice the pun, okay?)... far too many folks think the G5RV is the epitome of an all-band antenna. I don't think so, but if you do, fine. The truth is, there are better choices for an all-band antenna.
Alan, KØBG
www.k0bg.com
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RE: Some More Amateur Myths
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by KA4KOE on July 8, 2008
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"Power equals E*I. If the current flowing through a resistor is lowered as a result of increasing its resistance, then the voltage across the resistance must INCREASE in proportion to the decreased current if the power delivered into the load is held constant (through suitable, low-loss impedance matching)."
This is a misleading statement.If you are dealing with a purely resistive load in parallel with the voltage source, then the voltage across it remains constant, regardless of the magnitude of the resistive load.
Also, we almost never deal with a purely resistive load at the antenna feedpoint, except at the exact point of resonance. Shift either way up or down in frequency, and you introduce capacitive or reactive components, and their associated phase angles.
It's got an imaginary piece one has to consider.
Philip
KA4KOE
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RE: Some More Amateur Myths
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by KA4KOE on July 8, 2008
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"Myth: Hams take showers (or baths) before going to a hamfest."
I'd really, really, REALLY like to hear from Cal, K4JSR vis a vis his thoughts on THIS ONE.
CHOKE!! WHEEZE!!!
Philip
KA4KOE
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RE: Amateur Myths
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by W4LGH on July 8, 2008
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Best Ham Myth so far....
AA5JG said..."How about: "The ARRL cares about their members and does what's in the members' best interest?"
=====================================================
And some of you guys will NEVER get it about antenna tuners in your shack. There is a simple instrument that will show you, but probably being shown, you still won't get it. Its called a Field Strength Meter.
You probably don't own one, but it WILL tell teh whole truth. Near and Far fields and you'll see for yourself. Just because someone wrote a book, doesn't make it so! Look at the Bible..it was writen by experts too.
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Amateur Myths
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by AA4PB on July 8, 2008
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Someday, someone will write an antenna book for dummies. One that is not overly wordy but only states the basic facts without a lot of gibberish designed to fill the book with extra pages.
------------------------------------------------------
Thats why most of the myths have developed - because someone has a little bit of knowledge but doesn't understand all of the details. Often it results from a statement that is true in one application but miss-applied to a different application. Take for example, the statement that an antenna tuner in the shack results in an inefficient antenna system. Whether that is true or not depends on the frequency, the type of antenna and the length and type of feed line between the tuner and the antenna. You just can't take a statement like this and universally apply it to every situation.
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RE: Amateur Myths
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by W4LGH on July 8, 2008
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AA4PB says..."Whether that is true or not depends on the frequency, the type of antenna and the length and type of feed line between the tuner and the antenna. You just can't take a statement like this and universally apply it to every situation."
Aw...but you see it does apply, and is the same for ALL frequencies. Just because its an exceptable loss @ HF, and maybe NOT @ VHF or UHF, the rule is still the same! You know there were many books written stating that communications above 30mhz would NOT work, and they were experts who wrote them...and they too were taken as fact. We certainly KNOW thats its not a fact today.
So don't go thru life with blinder on, and believing everything you read is 100% factual.
How about if I re-word what I have been saying, and say matching/tuning @ the antenna will give better results, and less loss (even if its an exceptable loss @ HF) than tryng to tune your antenna with the tuner/match in your shack.
(But I still wanna see you feed an end-fed voltage 1/2wave with the match in your shack...)
73 de W4LGH - Alan
http://www.wlgh.com
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RE: Amateur Myths
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by N4JTE on July 8, 2008
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Just one more for old time sake; eham antenna reviews are relevant to the real world. Tnx Allan.
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RE: Some More Amateur Myths
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by K9MHZ on July 8, 2008
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>>>>by N5YPJ on July 8, 2008 Mail this to a friend!
Mandatory CW exams will keep out the riff raff.<<<<
Oh man, here we go again: code vs. no-code, Icom vs. Yaesu, Ginger vs. Mary Ann, tastes great vs. less filling, you suck vs. no, you suck!....
I've already got a headache.
Cheers,
Brad
K9MHZ
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RE: Amateur Myths
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by W5WSS on July 8, 2008
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ke4zhn your list has some funny stuff but ....seems to be kinda of extensive huh? oh and by the way a doublet isnt a dipole hehe
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Pinocchio
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by AI2IA on July 8, 2008
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There is an Italian red wine called Pinocchio from Dievole. On the label it says:
"There are those who live by what they know to be a lie, and those who live by what they believe, falsely, to be truth."
Perhaps you would enjoy a glass of this wine when you read this article.
I think that they would go well together.
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Amateur Myths
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by N0AH on July 8, 2008
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OK, I'll admit it. I bought one of those mini-G5RV's. Made for a great bird wire- Even the squirrels loved it-
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RE: Amateur Myths
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by N5ZTPN5ZTP on July 8, 2008
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if conditions are good enough, you can make a contact with a dummy load. aint that right Vern
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RE: Pinocchio
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by N3OX on July 8, 2008
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"And some of you guys will NEVER get it about antenna tuners in your shack"
Alan,
Do your experiment.
Set up a dummy load in a calorimeter. In fact, you can stick a tuner backwards on a dummy load, stick the whole tuner and dummy load in a big acrylic box full of transformer oil, stick that in a styrofoam cooler.
Connect a reasonable length (100ft is pretty standard for line loss measurements) of open wire line between the tuner in the box and another tuner.
Dial your oil-soaked variable impedance dummy load to a random setting. Match with the other tuner. Repeat.
Does each and every setting you randomly dial in cause significant, measurable loss? How much is that loss? You "bet" the dummy load won't get as hot in a given keydown period. But *I* bet you haven't tried it.
Like W8JI says, on a few settings, for a given transmission line, the dummy load might even get HOTTER. You take your 600 ohm line and run it at 600 ohms with a matching network at either end and the system's going to be quite low loss even if you use cheap tuners.
-=-=-=-=-=-=-
The myth? Antenna and transmission line physics are a matter of opinion.
73,
Dan
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RE: Amateur Myths
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by K9MHZ on July 8, 2008
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>>>>by N0AH on July 8, 2008 Mail this to a friend!
OK, I'll admit it. I bought one of those mini-G5RV's. Made for a great bird wire- Even the squirrels loved it<<<<
What's the deal on those that makes them no bueno sometimes....is it that you get some high voltage nodes in the twin lead at certain wavelengths?
Thanks,
Brad
K9MHZ
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RE: Some More Amateur Myths
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by K4JSR on July 8, 2008
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Feeeeee-lep sed, ""Myth: Hams take showers (or baths) before going to a hamfest."
I'd really, really, REALLY like to hear from Cal, K4JSR vis a vis his thoughts on THIS ONE.
CHOKE!! WHEEZE!!!
Philip KA4KOE"
Showers before going to a hamfest are perfectly okay as long as a few conventions are followed;
1. Showering in garlic juice and skunk sweat is a real necessity before going to a hamfest.
2. Proper diet is also in order. Lots of pickled eggs, stale beer, reconstituted dried beans, cabbage,
cauliflower and of course those famous five dollar rancid hamfest hotdogs with greasy fries. A pig ear
sandwich with sour kraut is nice also.
3. No deodorant or anti-perspirants allowed.
4. The weather must be hotter than Hades and you must sweat freely. Stay hydrated on stale beer and garlic juice so you can keep sweating to excess.
5. If there is no time for preparing in advance, one may always roll around in some rotted road kill just like your dog does just after being bathed.
With just a little malice of forethought you can keep
others from bugging you while haggling over some jewel
that you must possess. Also remember that you do this at each hamfest so that those who did not see you can still enjoy the ambience you bring!
Ah! Sharing! No hamfest should be without it!!
If you can't smell as sweet as a paper mill, don't go!
You may thank KA4KOE for this. He likes aroma therapy! Look at all of those Dead Electrical Dudes
he used to hang out with!
73, Cal K4JSR
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RE: Some More Amateur Myths
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by W7ETA on July 8, 2008
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Its fun to copy someone sending with a bug.
Its fun to copy QRP signals.
Larger diameter wire has more resistance than smaller diameter wire.
Current flows from + to minus.
73
Bob
PS: complaining about contest and/or contesters on eHam reduces contests.
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RE: Amateur Myths
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by AB7E on July 9, 2008
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K0BG: "A similar myth is floating around the internet with respect to placing the BALUN on the input, rather than the output of a tuner. That doesn't work, and in fact is adds insult to injury. "
Can you please explain for us in engineering terms why you call that a myth, assuming a properly designed tuner (floating components)? The balun is going to perform its job better at its design impedance, which is rarely the case when placed at the output of the tuner.
Dave AB7E
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RE: Amateur Myths
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by AB7E on July 9, 2008
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Myth: "Speaking of the lowly BALUN... It should always be printed in caps as it is an acronym for BALanced/UNbalanced."
Reality: http://dictionary.reference.com/browse/balun
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RE: Amateur Myths
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by G3RZP on July 9, 2008
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If you're going to the trouble of making a floating balanced tuner, why use a BALUN at all? Either a parallel or series tuned balanced circuit with a link winding coupling gets away from having a BALUN and does the necessary tuning. By adjusting component values and/or taps on the coil to get a working Q of around 5 to 10, the bandwidth is usually adequate and the losses low. Designs can be found in ARRL handbooks of the 1950's.
Another apparently prevalent myth is that DX stations working a pile up can listen at the same time as they are transmitting
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RE: Amateur Myths
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by KE4ZHN on July 9, 2008
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Robert W5WSS- I could have added much more but didnt want to make it too long. lol As for the doublet not being a dipole, I use a doublet and it performs quite nicely contrary to what a certain tuner hater likes to spew on here. Some choose to read the books and learn while others are content to believe amateur folklore and be closed minded about antenna systems.
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RE: Amateur Myths
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by N4BWV on July 9, 2008
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Jim Varney was an actor, now deceased. His body of work included the classic cinamatic masterpiece EARNEST GOES TO CAMP. Are you sure he didn't invent the G5RV.
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RE: Amateur Myths
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by N7YA on July 9, 2008
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...The majority of hams at the swapmeet shower regularly.
...arguments on the internet really DO matter.
...a bug is hard to copy when used properly.
...were still popular.
...that hamfest chilidog wont be a problem later on.
...etc, etc...
73...Adam, N7YA
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RE: Amateur Myths
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by N3OX on July 9, 2008
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Mail this to a friend!
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"Its fun to copy QRP signals. "
I think it's fun to copy QRP signals, like G3ROO's 3W on 80m CW from a vintage transmitter, and N0LX's pedestrian mobile 5W from CO on 20m. KH6MB's QRP signal on 20m phone...
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RE: Amateur Myths
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by W2VW on July 9, 2008
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Mail this to a friend!
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>A similar myth is floating around the internet with respect to placing the BALUN on the input, rather than the output of a tuner. That doesn't work, and in fact is adds insult to injury.
A BalUn on the input of a BALANCED antenna "tuner" will not have to deal with large reactances sometimes found at the output.
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RE: Amateur Myths
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by AA4PB on July 9, 2008
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Mail this to a friend!
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How about if I re-word what I have been saying, and say matching/tuning @ the antenna will give better results, and less loss (even if its an exceptable loss @ HF) than tryng to tune your antenna with the tuner/match in your shack.
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That turns it into a "true" statement. As a practical matter however using a tuner in the shack on HF with open wire line to feed an all-band doublet results in an "insignificant" amount of additional loss as compared to placing the tuner at the antenna with everything else being equal. As I said, where to place the tuner depends on a number of variables including the frequency, type and length of feed line, and type of antenna. Placing the tuner in the shack is NOT ALWAYS a bad idea. As with most things, it depends :-)
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RE: Amateur Myths
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by G8UBJ on July 9, 2008
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Mail this to a friend!
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If you call long enough bang on the frequency of that DX calling a split they will eventually reply, and let you know their call (You never bothered to check)
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Dave's Answer
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by K0BG on July 9, 2008
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Mail this to a friend!
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Rather than take space here, go to Tom's site (www.w8ji.com) and read what he says about placing the BALUN at the input of the tuner.
You can also look up the Strays and Technical Correspondence generated by the home brew tuner article which appeared in QST a few years ago, in which the BALUN was at the input.
I don't remember how far back, but a similar design was presented in QEX, and debunked for what it wasn't; better balanced.
Alan, KØBG
www.k0bg.com
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RE: Some More Amateur Myths
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by K9MHZ on July 9, 2008
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Mail this to a friend!
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>>>>by K4JSR on July 8, 2008
2. Proper diet is also in order. Lots of pickled eggs, stale beer, reconstituted dried beans, cabbage,
cauliflower and of course those famous five dollar rancid hamfest hotdogs with greasy fries. A pig ear
sandwich with sour kraut is nice also.<<<<
Cal,
You forgot the Diet Coke....you know, "An Amatuer is Balanced..."
Brad
K9MHZ
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