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Homebrew tuners
Seems like a lot of hams with limited resources are still compelled
to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
Art, are you sure you have a balun? Your description sounds like a tapped
r-f transformer. A balun, of course, is completely different from a transformer in that it is a "transmission line transformer" which is made of short transmission line sections instead of "windings." If a balun is made with line sections of Zo, then the load must be an appropriate multiple of Zo and purely resistive for the balun to function properly. Usually it is best to let a balun do the current steering and keep the outer braid of the coax "clean" and do the impedance matching elsewhere, as in a tuner. Just a thought . . . -- 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" "Art Unwin KB9MZ" wrote in message m... Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
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Yes George, I mispoke, you are correct
It says in very large letters on it " TRANSFORMER" Since transformers are touted as being efficient I was wondering how it would compare with the normal tuner. Half of the challenge for me was to come up with an inexpensive switching system where the input was stationary while the rest were switched thru and then repeated for the next input e.t.c. With that being solved I look forward to finishing and then playing with it Regards Art "George, W5YR" wrote in message ... Art, are you sure you have a balun? Your description sounds like a tapped r-f transformer. A balun, of course, is completely different from a transformer in that it is a "transmission line transformer" which is made of short transmission line sections instead of "windings." If a balun is made with line sections of Zo, then the load must be an appropriate multiple of Zo and purely resistive for the balun to function properly. Usually it is best to let a balun do the current steering and keep the outer braid of the coax "clean" and do the impedance matching elsewhere, as in a tuner. Just a thought . . . -- 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" "Art Unwin KB9MZ" wrote in message m... Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
Define 'Efficient' before you engage in this discussion.
"When I was a youngster, back in the olden golden days, transformer efficiencies exceeded 98%, but that was for 60 Cycle [olden days language] power distribution systems." H U G E G R I N Deacon Dave, W1MCE + + + W5DXP wrote: Art Unwin KB9MZ wrote: Since transformers are touted as being efficient I was wondering how it would compare with the normal tuner. Who touts transformers as being efficient? And efficient compared to what? |
Dave Shrader wrote:
Define 'Efficient' before you engage in this discussion. OK, let's say as efficient as a transmission line transformer over an entire range of frequencies. I don't think you will find a normal transformer that is as efficient as a transmission line transformer over the entire HF frequency range. But I could be wrong. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- |
Cecil, if I go back in time a long way, to the days of transformer
design, I recall that core loss increased as an exponential of frequency. The exponential was greater than '1.2' and less than '2.0'. Now, magnetic materials have changed, since the invention of the wheel, but I still suspect that losses in magnetic materials are exponential, even in new materials. So, in a transformer I would expect core loss to increase exponentially from 1.8 to 29.7 MHz. In a balun, well I don't know! Shortly after the invention of the wheel I came into the ownership of a B&W air wound balun rated at 250 watts continuous that I used for over 35 years. I dumped it as part of the move from Massachusetts to New Hampshire. That was DUMB! But, using air instead of magnetic material certainly minimized losses grin. Back to the Modern Age. How efficient is a transmission line transformer? [TBD %] Can you quantify a suitable number or will it remain a qualitative statement? Deacon Dave, W1MCE + + + W5DXP wrote: Dave Shrader wrote: Define 'Efficient' before you engage in this discussion. OK, let's say as efficient as a transmission line transformer over an entire range of frequencies. I don't think you will find a normal transformer that is as efficient as a transmission line transformer over the entire HF frequency range. But I could be wrong. |
Dave Shrader wrote:
Back to the Modern Age. How efficient is a transmission line transformer? [TBD %] Can you quantify a suitable number or will it remain a qualitative statement? Looking at some of the graphs in Jerry Sevick's book, _Transmission_ Line_Transformers_, it looks like about .05 dB maximum loss from 3 to 30 MHz. Note that figure is for perfectly matched resistive loads. A transmission line transformer carries a high flux density for common mode but not for differential mode. An ordinary transformer carries a high flux density for differential mode. That's got to make a difference. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- |
For design, frequency-response, insertion-loss of 4:1 impedance ratio,
transmission line HF transformers (voltage Baluns), download program BALUN4 from website below - --- ======================= Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.g4fgq.com ======================= |
Given that a 1dB change is NOT SUSPOSED to be noticed (without a meter, in
hearing, sight, ect. ), anyhow, Just what would be the Noticeable effect of / = .1 dB in the real world ? Would , say, 2/10's really kill you, or 1/100th dB extra get you that last DXCC country? As I say, am very cynical when ANYTHING gets into these kinds of numbers! Jim NN7K KB7QHC wrote: ------------------------------------------------- 50:12.5 Ohm with an insertion loss of around 0.1dB or less over the interval of 100KHz to 30MHz. AND THAT IS NOT THE BEST EXAMPLE OF LOW LOSS! 73's Richard Clark, KB7QHC |
I would suggest that anyone that strapped for cash use transmission line
segments for impedance matching. That is about as cheap as it gets. "Art Unwin KB9MZ" wrote in message m... Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
On Thu, 31 Jul 2003 17:07:10 -0700, wrote:
Given that a 1dB change is NOT SUSPOSED to be noticed (without a meter, in hearing, sight, ect. ), anyhow, Just what would be the Noticeable effect of / = .1 dB in the real world ? Would , say, 2/10's really kill you, or 1/100th dB extra get you that last DXCC country? As I say, am very cynical when ANYTHING gets into these kinds of numbers! Jim NN7K KB7QHC wrote: ------------------------------------------------- 50:12.5 Ohm with an insertion loss of around 0.1dB or less over the interval of 100KHz to 30MHz. AND THAT IS NOT THE BEST EXAMPLE OF LOW LOSS! 73's Richard Clark, KB7QHC Hi Jim, Cynical? This 0.1dB corresponds to about 2% error from perfect where too many think that 5% error is the worst they have to suffer from making a power measurement with their Bird (which actually doesn't do nearly that well in the first place due to these accumulations of error). It doesn't take long for error to accumulate to the 10's of percent where you couldn't convince the bench tech that he has too many places of precision in his pronouncement of measuring 104.5W (when it was in fact closer to somewhere between 85W to 115W). I can well anticipate the "so what?" rebuttal. "Who needs 5% accuracy?" being another. The general rule of thumb demands that your standard exhibit 3 times the accuracy of the instrument being calibrated (the Bird is already dead on arrival using this 0.1dB loss, if it were not characterized already). With an out of whack Bird, you barely qualify any power measurement to within 15% (and there are more sources of error than the BalUn used to isolate the Bird). Again, I am being generous with the 3 times rule (professionals generally seek 5 times and are more comfortable with 10 times). But this is all really the provence of the professional Metrologist, not the Amateur. For the Bench Tech that confidently made the 104.5W measurement (not knowing it was in fact closer to 60W) would hardly know it through contacts where they barely noticed the less than 1 S-Unit difference. Returning to this 0.1dB, it also represents a heat burden of 20W (or more, I am being generous) for each 1KW passing through. This is a lot of heat for small packages carelessly regarded as being trivial (after-all, who can see 0.1dB on their S-Meter?). There have been more than single reports of Hams writing here in astonishment of their BalUns exploding. Blame the BalUn seems to be a popular ballad played to that audience. Others pronounce with hushed tones of reverence remonstrating mankind for drifting from the true path of the air wound BalUn (or choke, what will you) mindless of the same loss, but gratified through ignorance of the greater heat mass. This 0.1dB in the wrong hands is clearly an example of extravagant dismissal or myopic attention. And speaking of hands, how long would you consider it trivial if you had to hold onto the sucker for 20 seconds? 73's Richard Clark, KB7QHC |
Jimmy wrote:
I would suggest that anyone that strapped for cash use transmission line segments for impedance matching. That is about as cheap as it gets. Yep, I bought an SGC-500 amp and didn't want to spring for a high power tuner. So I vary my window-line length to obtain a match. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- |
"Jimmy on reading the postings over time I see a lot of
people asking about the G5RV which is an inexpensive way of of operating on many bands. I thought that maybe a inexpensive way of matching such an antenna would be a cheap sort of tuner. I don't need a tuner, it was just an idea that popped into my head. Clark raised the subject of excess heat that I hadn't thought of but I am enjoying the challenge of putting together suitable mechanisms that would not be subject to breakdown, that one could place at a antenna feed point. If it explodes it would be more spectacular than having a neon light blinking during radio operation ! If one must have 1: 1 SWR at all times then they can spend a $200 amount or more to buy the SGC tuner ( I thing that in the name of the automatic tuner which I believe is limited with respect to power.) The mechanism I am making is a star shaped wheel with a slot in each point. It has a interconnecting rotary switch that sweep each transformer connection and when it has rotated once engages the star wheel so that it rotates a distance equal to the transformer connection where it stays in place for the next rotary switch rotation. Making the parts from a plastic sheet used to replace a glass window pane plus the use of a small hand grinding tool. Duing this in the garage to escape the heat Jimmy" wrote in message r.com... I would suggest that anyone that strapped for cash use transmission line segments for impedance matching. That is about as cheap as it gets. "Art Unwin KB9MZ" wrote in message m... Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
W5DXP wrote in message ...
Jimmy wrote: I would suggest that anyone that strapped for cash use transmission line segments for impedance matching. That is about as cheap as it gets. Yep, I bought an SGC-500 amp and didn't want to spring for a high power tuner. So I vary my window-line length to obtain a match. Cecil, the idea that you have is quite unique but I was thinking of the newby ham. To capture the future hams of tomorrow we must enable them to get them on the air as quickly and cheaply as possible and not dissuade them in any way as to how much they will be paying in the future, and that is where my thoughts lie. If a newcomer is to put up a G5RV so that he can get on the air quickly,I thought that buying a RF transformer would be a quick way of getting on the air and getting the taste for ham radio. To be honest Cecil no newby is going to struggle with your method in his early days. If one could arrange a way to run thru a series of impedance ratio's with just one knob then we have hooked those who are curious, even when using the most plainess of wires or the gutter we have fed the mind, remote control systems can come later. Frankly when you are hooked by ham radio money ceases to become an issue. Art |
I think it all boils down to signal to noise.
If you are trying to communicate with another station and he is putting out 100 watts and is not being copied and then he puts out 110 watts and you can copy him that is what counts. Bill N4WC wrote: Given that a 1dB change is NOT SUSPOSED to be noticed (without a meter, in hearing, sight, ect. ), anyhow, Just what would be the Noticeable effect of / = .1 dB in the real world ? Would , say, 2/10's really kill you, or 1/100th dB extra get you that last DXCC country? As I say, am very cynical when ANYTHING gets into these kinds of numbers! Jim NN7K KB7QHC wrote: ------------------------------------------------- 50:12.5 Ohm with an insertion loss of around 0.1dB or less over the interval of 100KHz to 30MHz. AND THAT IS NOT THE BEST EXAMPLE OF LOW LOSS! 73's Richard Clark, KB7QHC |
"Bill" wrote
I think it all boils down to signal to noise. If you are trying to communicate with another station and he is putting out 100 watts and is not being copied and then he puts out 110 watts and you can copy him that is what counts. =============================== Bill, sorry to be so pessimistic. If, because of bad signal to noise ratio you can't copy him when he's using 100 watts, then, as sure as eggs don't bounce off concrete, there's no hope of any detectable improvement by increasing power to 110 watts or 0.4 dB. Suppose when he's using 100 watts you can hear only 25% of words (or morse characters). So you can't copy him. If he doubles power to 200 watts you will still read only 40% of what he says. So you still can't copy. If he doubles power again to 400 watts you will be able to copy 60% of what he says. You will still be in big trouble. At 800 watts 80% of words (or characters) will be OK but it's not solid copy. Requests to repeat will be common. At 1600 watts 99% of words (or characters) will be OK and that's solid enough. There are many assumptions in the foregoing crude analysis. But as many have experienced it is typical. Claude E. Shannon's (of Bell Labs) original classical paper on the subject of "Communication in the Presence of Noise", Jan. 1949 can be downloaded (I have just discovered) by doing a Google on the title. Radio and phone engineers had been trying for 40 years to describe in precise mathematical terms the effects of noise and cross-talk in a communication channels. The transistor had just been invented. So had PCM pre-war. But progress in the design of the vast communication digital networks then envisaged and which we now see was being impeded by the lack of understanding of the effects of ever-present random noise. It was basically a problem in Statistics. But Shannon went off at a tangent back to Geometry where Pythagorus the ancient Greek had begun. He translated the statistical problem into one of calculating the number of small spheres which can be packed inside a much larger multi-dimensional sphere. The calculating procedure acquired the everlasting name of "Ball Packing". It is not difficult to understand. It was Shannon's dazzling multi-coloured flash of inspiration which did the trick. His name has gone down in history. Think of him the next time your electric light dimmer-switch goes faulty. Following Shannon progress forged ahead. In-words such as signal-to-noise ratios and error-rates became very popular. A one-dimension sphere is a dot. A 2-dimension sphere is a flat circular disk. A 3-dimension sphere is a ball. Followed by N-dimensions, all of which have a surface area and and a volume involving Pi. ---- Reg. |
And we can look at it going the other way. I can
run my FT-817 with its 5 watt signal for a lot less money than my friend Jim can operate his kilowatt. If the band is open The difference between my 5 watt signal and his 1000 watt signal is 2 or three S units at the far end of the circuit. Not enough to be really noticeable. If the band is closed, nobody is talking long distance, the band is closed. Now when conditions are marginal he has a decided advantage. Right now I am happy burning a kilowatt of power purchased from the electric company every 15 hours while he gets about 20 minutes operating time for his station for the same dollars. -- 73 es cul wb3fup a Salty Bear "Ian White, G3SEK" wrote in message ... Reg Edwards wrote: Suppose when he's using 100 watts you can hear only 25% of words (or morse characters). So you can't copy him. If he doubles power to 200 watts you will still read only 40% of what he says. So you still can't copy. If he doubles power again to 400 watts you will be able to copy 60% of what he says. You will still be in big trouble. At 800 watts 80% of words (or characters) will be OK but it's not solid copy. Requests to repeat will be common. At 1600 watts 99% of words (or characters) will be OK and that's solid enough. There are many assumptions in the foregoing crude analysis. But as many have experienced it is typical. Typical for a machine, but not for a human being. For humans, "copying" very weak speech or Morse is mostly about *understanding* it as language. In conversational speech, we don't always hear every word. Our minds are remarkably good at filling in gaps by using the broader context of the whole sentence. Even if you don't hear a word clearly, you can hear a word was there and your mind will automatically make a good guess, based on what we did hear before and after. It happens all the time, in conversations both on and off the air, and you don't even notice yourself doing it. It's more obvious when copying Morse, where we more often fill in individual letters, but sometimes also whole words. We make very clever guesses about what the letter could have been, based on what we did manage to hear. Often there is a threshold effect. Below that threshold, you can hear quite a lot but it doesn't make sense as language. Just above the threshold, it clicks into context and you can understand a whole stretch... and then maybe we lose it again. It's also like listening to a language we only "half" know. That doesn't mean we understand a certain percentage of individual words, as a machine might. The way it really works with human beings, we're suddenly delighted to find ourselves understanding whole sentences... and then, just as suddenly, we lose it again completely. The exceptions are for certain key items like a callsign, name, QTH or contest exchange. These items come one by one (without context) and must be logged with 100% accuracy, so then it's rather more mechanical like Reg describes. But even for key words like phonetics, there is a threshold between hearing a sound, and that sound resolving itself into a recognisable word. As any DXer knows, the threshold between "getting it" and "losing it" can indeed be as little as 1dB. The more serious you are about working right down to that threshold, the more that last 1dB matters. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) Editor, 'The VHF/UHF DX Book' http://www.ifwtech.co.uk/g3sek |
"Art Unwin KB9MZ" wrote in message . .. W5DXP wrote in message ... Jimmy wrote: I would suggest that anyone that strapped for cash use transmission line segments for impedance matching. That is about as cheap as it gets. Yep, I bought an SGC-500 amp and didn't want to spring for a high power tuner. So I vary my window-line length to obtain a match. Cecil, the idea that you have is quite unique but I was thinking of the newby ham. To capture the future hams of tomorrow we must enable them to get them on the air as quickly and cheaply as possible and not dissuade them in any way as to how much they will be paying in the future, and that is where my thoughts lie. If a newcomer is to put up a G5RV so that he can get on the air quickly,I thought that buying a RF transformer would be a quick way of getting on the air and getting the taste for ham radio. To be honest Cecil no newby is going to struggle with your method in his early days. If one could arrange a way to run thru a series of impedance ratio's with just one knob then we have hooked those who are curious, even when using the most plainess of wires or the gutter we have fed the mind, remote control systems can come later. Frankly when you are hooked by ham radio money ceases to become an issue. Art Actually I would think a newbie would be the one most likely to embrace Cecil's method. Its the guys who have been around a while who want everything controlled at their armchair(like me). This is not to say that Cecils method could not be controoled from the shack, Just replace some of those switches with relays and maybe make some custum impedance feedline for even a better match that what he shows though you dont really need it. This sort of setup could even be controlled by a lot of radios that provide for a means of automatic antenna switching. |
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Jimmy wrote:
"W5DXP" wrote: I control the switches from my shack. They are mounted on a piece of plexiglas sitting vertical in a window. It takes less time to throw the switches than to tune an antenna tuner. Really, some how or other I got the impression you had to go outside to change bands. The window-line loops are outside but the switches are inside. I've got a chart on the wall that makes changing bands a snap from the operating position. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- |
In a time long, long ago, there were no commercial antenna tuners that
I can recall. The first commercial tuner I remember was the Johnson Viking. Everyone I knew made their own. You just went to the surplus store, and got a coil and capacitor that looked about right, and tried it. No one owned any equipment to measure them anyway. We never used relays. Maybe a switch, or just change the coil. The ARRL handbook and Antenna Handbooks still have diagrams for antenna tuners. Also the Hints and Kinks manuals, among many others. Dick - W6CCD On 4 Aug 2003 12:51:51 -0700, (Art Unwin KB9MZ) wrote: Mark, What sort of range of impedance matching would this provide? How would you switch bands and what voltage/capacitor range would be required? I suspect you would have to have several relays to pick up various points on the oatmeal inductor as well as a rotation method for the capacitor Seems like you have something specific in mind that you would put in a box for safety reasons. Are the specifics shown somewhere for people to copy? Art |
Dick, A REAL LONG time ago when I needed my first tuner I bought a
military surplus ARC-5 transmitter for $5 USD and removed the roller inductor and final plate tuning capacitor. [Actually, I bought 3 ARC-5s: one for 80, one for 40 both converted to XTAL control, and one for the tuner and spare 1625s. Nice NOVICE CW rigs.] Made a real nice L-tuner at 125 watts continuous duty!! Hmmm .... where are those old ARC-5s when someone needs them?? Deacon Dave, W1MCE Dick wrote: In a time long, long ago, there were no commercial antenna tuners that I can recall. The first commercial tuner I remember was the Johnson Viking. Everyone I knew made their own. You just went to the surplus store, and got a coil and capacitor that looked about right, and tried it. No one owned any equipment to measure them anyway. We never used relays. Maybe a switch, or just change the coil. The ARRL handbook and Antenna Handbooks still have diagrams for antenna tuners. Also the Hints and Kinks manuals, among many others. Dick - W6CCD On 4 Aug 2003 12:51:51 -0700, (Art Unwin KB9MZ) wrote: Mark, What sort of range of impedance matching would this provide? How would you switch bands and what voltage/capacitor range would be required? I suspect you would have to have several relays to pick up various points on the oatmeal inductor as well as a rotation method for the capacitor Seems like you have something specific in mind that you would put in a box for safety reasons. Are the specifics shown somewhere for people to copy? Art |
Did the same thing!! Even used the chasis! Sawed it off, moved the front
cover/ cap, and rotary inductor into the area of the osc/ magic eye tuneing tube area-- makes nice package, and considering these tuned from around 160 meters thru 20 (or thereabouts) in different versions, and loaded a aprox 20 foot piece of wire--- make very versatile tuners . also wonder where all of the bazillions of these dissapeared to! Jim Dave wrote: Dick, A REAL LONG time ago when I needed my first tuner I bought a military surplus ARC-5 transmitter for $5 USD and removed the roller inductor and final plate tuning capacitor. [Actually, I bought 3 ARC-5s: one for 80, one for 40 both converted to XTAL control, and one for the tuner and spare 1625s. Nice NOVICE CW rigs.] Made a real nice L-tuner at 125 watts continuous duty!! Hmmm .... where are those old ARC-5s when someone needs them?? Deacon Dave, W1MCE Dick wrote: In a time long, long ago, there were no commercial antenna tuners that I can recall. The first commercial tuner I remember was the Johnson Viking. Everyone I knew made their own. You just went to the surplus store, and got a coil and capacitor that looked about right, and tried it. No one owned any equipment to measure them anyway. We never used relays. Maybe a switch, or just change the coil. The ARRL handbook and Antenna Handbooks still have diagrams for antenna tuners. Also the Hints and Kinks manuals, among many others. Dick - W6CCD On 4 Aug 2003 12:51:51 -0700, (Art Unwin KB9MZ) wrote: Mark, What sort of range of impedance matching would this provide? How would you switch bands and what voltage/capacitor range would be required? I suspect you would have to have several relays to pick up various points on the oatmeal inductor as well as a rotation method for the capacitor Seems like you have something specific in mind that you would put in a box for safety reasons. Are the specifics shown somewhere for people to copy? Art |
On Tue, 5 Aug 2003 16:15:32 -0700, wrote:
Well, depends on HOW CLOSE to my flesh I held it! (according to the inverse -square law, temperature decreases at a rate of 1/4 , for every 1/2 of an increment it is removed from you)! Jim NN7K Richard wrote: This 0.1dB in the wrong hands is clearly an example of extravagant dismissal or myopic attention. And speaking of hands, how long would you consider it trivial if you had to hold onto the sucker for 20 seconds? 73's Richard Clark, KB7QHC Hi Jim, How close is anything to your flesh when you are holding it? Are you still holding it, if it were 2 times further away? 73's Richard Clark, KB7QHC |
Jim, NN7K wrote:
"also wonder where all those bazillions of these disappeared to!" I think all the offshore counterfeiters of ARC-5 and 274-N equipment switched to modern equipment production when demand dwindled for surplus radios. Too bad! Best regards, Richard Harrison, KB5WZI |
Well, Richard, tho in jest, serves purpose, that even with 30 watts lost on
surface of a balun , (or any other surface, for thatr matter), that by doubleing the size of the SURFACE, that it would take something like 4 TIMES as much heat to destroy it. For the same reason that a transistor, in the size of a micron will vaporize with a slight static discharge , doesn't necessarily mean that a POWER transistor will even feel a hickup, if it takes you 30 minutes with a 100 watt soldering iron trying to get solder on the leads! For the same reason , have 50 ohm coaxial resistor that fits in a reducer for rg-174, to a SO-239, that would probably crack, with the heat, and meantime also have a resistor, 1/3 the size, but made to mount on a heat sink, that will dissipate 100 watts all day! (also made as a 50 ohm load-- same devices, but different uses-- Jim Hi Jim, How close is anything to your flesh when you are holding it? Are you still holding it, if it were 2 times further away? 73's Richard Clark, KB7QHC |
On Wed, 6 Aug 2003 15:48:01 -0700, wrote:
Well, Richard, tho in jest, serves purpose, that even with 30 watts lost on surface of a balun , (or any other surface, for thatr matter), that by doubleing the size of the SURFACE, that it would take something like 4 TIMES as much heat to destroy it. Hi Jim, No, this is incorrect. When discussing power dissipation, it follows a linear relationship to surface area - not square law (you are mixing radius and surface area arguments). Even letting this pass, power dissipation does not even conform to doubling with doubling of surface area. This departure from expectation arises in the increased distance the heat has to travel to find the surface. This is usually found in having too many fins in an effort to maximize that same surface area (and leads to an increase in Thermal Resistance). Further, more fins also diminish heat transfer through convection (again increasing Thermal Resistance). 4 or 5 fins is usually optimal. 73's Richard Clark, KB7QHC |
I read some of the return messages and I noticed that the message initially
openned by saying that many hams still use a long wire and tuner. He comments to say that the long wire is cheap but the tuner is not. That kinda hit a cord with me because of my antenna experiences. I have been an amateur since 1964, thats not a brag just a comment. Besides using a random wire antenna, I have tried multi-band dipoles, quads, beams, folded dipoles and others. However, I still keep coming back to my old reliable random wire, about 60ish feet and an L network (the coil connecting to the transmitter and the capacitor connecting between the ground and the common connection of the coil and antenna). Though a very simple circuit, it works very well. Recently I put up a 30ish foot random wire and found that it didn't work on 80, using the L network. After some thought, I broke the random wire and inserted a coil. I now gives me a good swr on 80 meters. I just wanted to defend cheap, but highly functional, antenna couplers and cheap but useful random wires. Larry ve3fxq Sorry if I have come accross a little rough sounding. "Art Unwin KB9MZ" wrote in message m... Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
I used to use a homebrew tapped transformer like the Palomar, wound on
a Philips 4C6 toroid, around late 70's to match my homebrew helical mobile whips to my Atlas 210X installed in my Austin 1800 (like a Mini on steroids and affectionately known as the "land crab"). The separate whips, for 80 40 and 20 metres, could all be matched to 50 ohms, all I had to do when changing bands was to change the whip, turn the selector switch to the appropriate tapping and away we went. Best dx - when mobile one afternoon, I heard a VK4 (across the pond in Aus) calling CQ on 40m, but when I went back to him found he was a DK4. MikeN ZL1BNB bnb On 29 Jul 2003 08:50:27 -0700, (Art Unwin KB9MZ) wrote: Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
Mike.
Why I chose a switchable transformer is the antenna I use is always made resonant because of remote variable lumped constants. ( The loop antenna is a similar type antenna ) Thus for me I only have to deal with RESISTIVE resonant impedances that vary from frequency to frequency. The Palomar provides a lot of different ratios between all inputs and outputs thus SWR of less than 1.3 is really a snap. As far as efficiency goes I should have defined efficiency but then it comes down to compared to what. I suppose a telephone call would be the best no matter how efficiency is defined. As far as radio goes a remotely switchable TRANSFORMER placed at the antenna input would be hard to beat no matter how one defines efficiency. Now a wag will enter bringing up the subject of inter coil capacitances in a transformer. Regards Art MikeN wrote in message . .. I used to use a homebrew tapped transformer like the Palomar, wound on a Philips 4C6 toroid, around late 70's to match my homebrew helical mobile whips to my Atlas 210X installed in my Austin 1800 (like a Mini on steroids and affectionately known as the "land crab"). The separate whips, for 80 40 and 20 metres, could all be matched to 50 ohms, all I had to do when changing bands was to change the whip, turn the selector switch to the appropriate tapping and away we went. Best dx - when mobile one afternoon, I heard a VK4 (across the pond in Aus) calling CQ on 40m, but when I went back to him found he was a DK4. MikeN ZL1BNB bnb On 29 Jul 2003 08:50:27 -0700, (Art Unwin KB9MZ) wrote: Seems like a lot of hams with limited resources are still compelled to operate on many bands with just a long wire and a tuner. The wire is inexpensive but the tuners are not. Thus my present project. I was given a Palomar enginnering balun with 5 female connenection which by selection can match a antenna in steps from 5 ohms to over 450 ohms in a series of steps. I am presently rigging it up so that all steps can be switched thru remotely by a single motor. The switching arrangement is the main challenge since inexpensive means simple. Now I have not measured losses of the balun before hand because the switching challenge is what is driving me. Anybody have any thoughts about what I should expect from this balun other than knowing that it is not a tuner as is generally known since it does not have the ability to obtain the priceless 1:1 condition that so many desire? Regards Art |
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