most efficient 80m antenna?
alf, Sun Apr 08 2012, 09:45AMhi,
i need to make an 80m antenna to use with the CW transmitter i made...
the thing is, the O/P power of the TX is only 7w max, so (unless i'm missing something)
the antenna would need to be as efficient as possible as to radiate a reasonable amount of power,
unfortunately i dont have 80m of space for a full-wave dipole, but i could make room for 20m
it doesnt need to operate on multiple bands, only 80m (3.58mhz)
i'm thinking that a coiled dipole is the correct thing, but idk anything about antennas.
any ideas?
thx in adv, Alf.
Re: most efficient 80m antenna?
Proud Mary, Sun Apr 08 2012, 01:54PM
In favourable conditions, 7W CW will give you a reach of hundreds of miles and sometimes further at 3.5Mhz, with even a mediocre, makeshift antenna, such as a long wire thrown up into a tree.
The choice of antenna will be governed by local variables, the space and height availlable, limitations on height imposed by planning permission and proximity to aerodromes, accessible 'free' high points such as roofs and trees, signal 'shadows' caused by mountains and buildings, proximity to large metal structures, local EMI that can be reduced by a particular antenna orientation, ground conductivity, and last - but by no means least - money.
So if you'd like to tell us a bit more about the proposed antenna location, you'll get more helpful replies.
Proud Mary, Sun Apr 08 2012, 01:54PM
In favourable conditions, 7W CW will give you a reach of hundreds of miles and sometimes further at 3.5Mhz, with even a mediocre, makeshift antenna, such as a long wire thrown up into a tree.
The choice of antenna will be governed by local variables, the space and height availlable, limitations on height imposed by planning permission and proximity to aerodromes, accessible 'free' high points such as roofs and trees, signal 'shadows' caused by mountains and buildings, proximity to large metal structures, local EMI that can be reduced by a particular antenna orientation, ground conductivity, and last - but by no means least - money.
So if you'd like to tell us a bit more about the proposed antenna location, you'll get more helpful replies.
Re: most efficient 80m antenna?
alf, Mon Apr 09 2012, 11:58AM
thx for ur reply,
i wouldnt worry too much about planning permission cuz its not permament, it can be removed at any time i guess.
there are no aerodromes, no high mountains or buildings...
its going in ze garden, lol between 2 trees, it can go as high as the trees i guess, 10m or something,
the antenna could be 20m long (horizontally) max.
and id hope as cheap as possible hehehe.
alf, Mon Apr 09 2012, 11:58AM
Proud Mary wrote ...
In favourable conditions, 7W CW will give you a reach of hundreds of miles and sometimes further at 3.5Mhz, with even a mediocre, makeshift antenna, such as a long wire thrown up into a tree.
The choice of antenna will be governed by local variables, the space and height availlable, limitations on height imposed by planning permission and proximity to aerodromes, accessible 'free' high points such as roofs and trees, signal 'shadows' caused by mountains and buildings, proximity to large metal structures, local EMI that can be reduced by a particular antenna orientation, ground conductivity, and last - but by no means least - money.
So if you'd like to tell us a bit more about the proposed antenna location, you'll get more helpful replies.
In favourable conditions, 7W CW will give you a reach of hundreds of miles and sometimes further at 3.5Mhz, with even a mediocre, makeshift antenna, such as a long wire thrown up into a tree.
The choice of antenna will be governed by local variables, the space and height availlable, limitations on height imposed by planning permission and proximity to aerodromes, accessible 'free' high points such as roofs and trees, signal 'shadows' caused by mountains and buildings, proximity to large metal structures, local EMI that can be reduced by a particular antenna orientation, ground conductivity, and last - but by no means least - money.
So if you'd like to tell us a bit more about the proposed antenna location, you'll get more helpful replies.
thx for ur reply,
i wouldnt worry too much about planning permission cuz its not permament, it can be removed at any time i guess.
there are no aerodromes, no high mountains or buildings...
its going in ze garden, lol between 2 trees, it can go as high as the trees i guess, 10m or something,
the antenna could be 20m long (horizontally) max.
and id hope as cheap as possible hehehe.
Re: most efficient 80m antenna?
Proud Mary, Mon Apr 09 2012, 12:48PM
If you haven't got any dogbone antenna insulators, buy these:
(I have dealt with this seller several times, and he seems honest.)
Obtain some nylon or polypropylene cord/thin rope strong enough to to take the strain when the antenna and trees are flexing in the wind.
Pace out the distance between the trees. You have to bridge this gap as follows: cord - insulator - antenna wire - insulator - cord. Make sure the cord is long enough at either end so that the insulators are clear of the branches.
Now before cutting any of your cord, you can make your life easier if you thread the cord through one eye of the dogbone like a pulley, so you can raise and lower the antenna from the ground.
You also have to make a decision about the feeder. You can either (A) take the coax directly to one end of the antenna, making it fast to the dogbone to relieve strain on the electrical connection, OR (B) you can use the antenna in an "L" configuration, continuing the antenna wire downward from the dogbone directly to the back of the sender, or to a coaxial cable at some point in between.
How to choose? Well, if the "L" configuration (whose geometry is not very important) would take the antenna downlead close to domestic cables, other coaxial cables etc, I would choose to take the coaxial feeder all the way out to the first dogbone.
What wire to use? There are quite a few 'antenna wires' aimed at the amateur market, but green//yellow single 6mm Earth bonding wire as used in domestic installations will do just as good a job, and will not be hard to find.
Solder the connection of the coaxial inner to the antenna wire, and coat liberally with a flexible non-conductive sealant, or self-almagamating tape.
Don't put too much tension on the antenna. A dead straight line is not necessary. A slight curve will allow for flexing of the trees in heavy weather.
Don't fall out of the tree!
PS: I've just glanced at the power oscillator circuit with the EL84 that you've linked to. The unfiltered output will radiate every harmonic under the sun, right up into the VHF, so you may become a star of your neighbour's radio and TV sooner than you'd ever have dreamed possible. Strictly speaking, you should do all this setting up and reduction of harmonics with a dummy load, but get the thing off the ground, Alf, and then you can worry about attenuating unwanted emissions with a basic C-L-C pi filter next.
Proud Mary, Mon Apr 09 2012, 12:48PM
If you haven't got any dogbone antenna insulators, buy these:
(I have dealt with this seller several times, and he seems honest.)
Obtain some nylon or polypropylene cord/thin rope strong enough to to take the strain when the antenna and trees are flexing in the wind.
Pace out the distance between the trees. You have to bridge this gap as follows: cord - insulator - antenna wire - insulator - cord. Make sure the cord is long enough at either end so that the insulators are clear of the branches.
Now before cutting any of your cord, you can make your life easier if you thread the cord through one eye of the dogbone like a pulley, so you can raise and lower the antenna from the ground.
You also have to make a decision about the feeder. You can either (A) take the coax directly to one end of the antenna, making it fast to the dogbone to relieve strain on the electrical connection, OR (B) you can use the antenna in an "L" configuration, continuing the antenna wire downward from the dogbone directly to the back of the sender, or to a coaxial cable at some point in between.
How to choose? Well, if the "L" configuration (whose geometry is not very important) would take the antenna downlead close to domestic cables, other coaxial cables etc, I would choose to take the coaxial feeder all the way out to the first dogbone.
What wire to use? There are quite a few 'antenna wires' aimed at the amateur market, but green//yellow single 6mm Earth bonding wire as used in domestic installations will do just as good a job, and will not be hard to find.
Solder the connection of the coaxial inner to the antenna wire, and coat liberally with a flexible non-conductive sealant, or self-almagamating tape.
Don't put too much tension on the antenna. A dead straight line is not necessary. A slight curve will allow for flexing of the trees in heavy weather.
Don't fall out of the tree!
PS: I've just glanced at the power oscillator circuit with the EL84 that you've linked to. The unfiltered output will radiate every harmonic under the sun, right up into the VHF, so you may become a star of your neighbour's radio and TV sooner than you'd ever have dreamed possible. Strictly speaking, you should do all this setting up and reduction of harmonics with a dummy load, but get the thing off the ground, Alf, and then you can worry about attenuating unwanted emissions with a basic C-L-C pi filter next.
Re: most efficient 80m antenna?
alf, Tue Apr 10 2012, 11:56AM
thank-you! :D
what kind of antenna is this? :)
ahh okay, im still struggling with getting the regen receiver to oscillate anywayz xD
the cw transmitter doesnt work so well now, the O/P power is greatly decreased...
maybe the crystal has failed or something
thanks again, Alf.
alf, Tue Apr 10 2012, 11:56AM
Proud Mary wrote ...
If you haven't got any dogbone antenna insulators, buy these:
(I have dealt with this seller several times, and he seems honest.)
Obtain some nylon or polypropylene cord/thin rope strong enough to to take the strain when the antenna and trees are flexing in the wind.
Pace out the distance between the trees. You have to bridge this gap as follows: cord - insulator - antenna wire - insulator - cord. Make sure the cord is long enough at either end so that the insulators are clear of the branches.
Now before cutting any of your cord, you can make your life easier if you thread the cord through one eye of the dogbone like a pulley, so you can raise and lower the antenna from the ground.
You also have to make a decision about the feeder. You can either (A) take the coax directly to one end of the antenna, making it fast to the dogbone to relieve strain on the electrical connection, OR (B) you can use the antenna in an "L" configuration, continuing the antenna wire downward from the dogbone directly to the back of the sender, or to a coaxial cable at some point in between.
How to choose? Well, if the "L" configuration (whose geometry is not very important) would take the antenna downlead close to domestic cables, other coaxial cables etc, I would choose to take the coaxial feeder all the way out to the first dogbone.
What wire to use? There are quite a few 'antenna wires' aimed at the amateur market, but green//yellow single 6mm Earth bonding wire as used in domestic installations will do just as good a job, and will not be hard to find.
Solder the connection of the coaxial inner to the antenna wire, and coat liberally with a flexible non-conductive sealant, or self-almagamating tape.
Don't put too much tension on the antenna. A dead straight line is not necessary. A slight curve will allow for flexing of the trees in heavy weather.
Don't fall out of the tree!
PS: I've just glanced at the power oscillator circuit with the EL84 that you've linked to. The unfiltered output will radiate every harmonic under the sun, right up into the VHF, so you may become a star of your neighbour's radio and TV sooner than you'd ever have dreamed possible. Strictly speaking, you should do all this setting up and reduction of harmonics with a dummy load, but get the thing off the ground, Alf, and then you can worry about attenuating unwanted emissions with a basic C-L-C pi filter next.
If you haven't got any dogbone antenna insulators, buy these:
(I have dealt with this seller several times, and he seems honest.)
Obtain some nylon or polypropylene cord/thin rope strong enough to to take the strain when the antenna and trees are flexing in the wind.
Pace out the distance between the trees. You have to bridge this gap as follows: cord - insulator - antenna wire - insulator - cord. Make sure the cord is long enough at either end so that the insulators are clear of the branches.
Now before cutting any of your cord, you can make your life easier if you thread the cord through one eye of the dogbone like a pulley, so you can raise and lower the antenna from the ground.
You also have to make a decision about the feeder. You can either (A) take the coax directly to one end of the antenna, making it fast to the dogbone to relieve strain on the electrical connection, OR (B) you can use the antenna in an "L" configuration, continuing the antenna wire downward from the dogbone directly to the back of the sender, or to a coaxial cable at some point in between.
How to choose? Well, if the "L" configuration (whose geometry is not very important) would take the antenna downlead close to domestic cables, other coaxial cables etc, I would choose to take the coaxial feeder all the way out to the first dogbone.
What wire to use? There are quite a few 'antenna wires' aimed at the amateur market, but green//yellow single 6mm Earth bonding wire as used in domestic installations will do just as good a job, and will not be hard to find.
Solder the connection of the coaxial inner to the antenna wire, and coat liberally with a flexible non-conductive sealant, or self-almagamating tape.
Don't put too much tension on the antenna. A dead straight line is not necessary. A slight curve will allow for flexing of the trees in heavy weather.
Don't fall out of the tree!
PS: I've just glanced at the power oscillator circuit with the EL84 that you've linked to. The unfiltered output will radiate every harmonic under the sun, right up into the VHF, so you may become a star of your neighbour's radio and TV sooner than you'd ever have dreamed possible. Strictly speaking, you should do all this setting up and reduction of harmonics with a dummy load, but get the thing off the ground, Alf, and then you can worry about attenuating unwanted emissions with a basic C-L-C pi filter next.
thank-you! :D
what kind of antenna is this? :)
ahh okay, im still struggling with getting the regen receiver to oscillate anywayz xD
the cw transmitter doesnt work so well now, the O/P power is greatly decreased...
maybe the crystal has failed or something
thanks again, Alf.
Re: most efficient 80m antenna?
Proud Mary, Tue Apr 10 2012, 12:41PM
I'd call it "a long wire" or "end-fed long wire".
Quartz crystals: The crystals used in the heyday of single valve power oscillator transmitters like yours - the 1930s and 40s - were very much more robust and were designed to handle much higher power levels than one would expect today. So you may have overdriven your crystal, which may now be fractured, and continuing to resonate, but without its original enthusiasm.
To use modern crystals to their best advantage with a valve oscillator, it is best to generate the signal at the lowest level at which the circuit will still oscillate reliably and then amplify the signal by means of a buffer amplifier, which isolates the oscillator, and stop it being 'pulled' by changes in the power amplifier. This configuration uses three valves - oscillator, buffer amplifier, and power amplifier - but you can get away with two in one envelope - for example, a triode output pentode - with some some sacrifice of quality.
If you put up the circuit of your superregen, we can think about why it isn't working properly.
Proud Mary, Tue Apr 10 2012, 12:41PM
I'd call it "a long wire" or "end-fed long wire".
Quartz crystals: The crystals used in the heyday of single valve power oscillator transmitters like yours - the 1930s and 40s - were very much more robust and were designed to handle much higher power levels than one would expect today. So you may have overdriven your crystal, which may now be fractured, and continuing to resonate, but without its original enthusiasm.
To use modern crystals to their best advantage with a valve oscillator, it is best to generate the signal at the lowest level at which the circuit will still oscillate reliably and then amplify the signal by means of a buffer amplifier, which isolates the oscillator, and stop it being 'pulled' by changes in the power amplifier. This configuration uses three valves - oscillator, buffer amplifier, and power amplifier - but you can get away with two in one envelope - for example, a triode output pentode - with some some sacrifice of quality.
If you put up the circuit of your superregen, we can think about why it isn't working properly.
Re: most efficient 80m antenna?
alf, Tue Apr 10 2012, 06:18PM
ahh right,
so is that quarter wavelength? :)
ooh that would make sense with whats happening... what if i parallel/series a few xtals?
haha thanks but i got the regen receiver working :D, i hadnt connected the cathode to negative. lol.
havent heard anything yet, just hissing, squeaking xD
btw, i wanna use the regen rx ( ) to receive 80m cw...
would the tone be generated automatically by the receiver or would i have to make a separate beat frequency oscillator?
thanks again, Alf.
alf, Tue Apr 10 2012, 06:18PM
Proud Mary wrote ...
I'd call it "a long wire" or "end-fed long wire".
Quartz crystals: The crystals used in the heyday of single valve power oscillator transmitters like yours - the 1930s and 40s - were very much more robust and were designed to handle much higher power levels than one would expect today. So you may have overdriven your crystal, which may now be fractured, and continuing to resonate, but without its original enthusiasm.
To use modern crystals to their best advantage with a valve oscillator, it is best to generate the signal at the lowest level at which the circuit will still oscillate reliably and then amplify the signal by means of a buffer amplifier, which isolates the oscillator, and stop it being 'pulled' by changes in the power amplifier. This configuration uses three valves - oscillator, buffer amplifier, and power amplifier - but you can get away with two in one envelope - for example, a triode output pentode - with some some sacrifice of quality.
If you put up the circuit of your superregen, we can think about why it isn't working properly.
I'd call it "a long wire" or "end-fed long wire".
Quartz crystals: The crystals used in the heyday of single valve power oscillator transmitters like yours - the 1930s and 40s - were very much more robust and were designed to handle much higher power levels than one would expect today. So you may have overdriven your crystal, which may now be fractured, and continuing to resonate, but without its original enthusiasm.
To use modern crystals to their best advantage with a valve oscillator, it is best to generate the signal at the lowest level at which the circuit will still oscillate reliably and then amplify the signal by means of a buffer amplifier, which isolates the oscillator, and stop it being 'pulled' by changes in the power amplifier. This configuration uses three valves - oscillator, buffer amplifier, and power amplifier - but you can get away with two in one envelope - for example, a triode output pentode - with some some sacrifice of quality.
If you put up the circuit of your superregen, we can think about why it isn't working properly.
ahh right,
so is that quarter wavelength? :)
ooh that would make sense with whats happening... what if i parallel/series a few xtals?
haha thanks but i got the regen receiver working :D, i hadnt connected the cathode to negative. lol.
havent heard anything yet, just hissing, squeaking xD
btw, i wanna use the regen rx (
) to receive 80m cw... would the tone be generated automatically by the receiver or would i have to make a separate beat frequency oscillator?
thanks again, Alf.
Re: most efficient 80m antenna?
Proud Mary, Tue Apr 10 2012, 07:51PM
My encouragement has been directed at the so-called random wire antenna as I think this will be easiest for you to get started with, and can usually produce very satisfactory results for a small outlay. There's a useful blurb about random lengths to avoid here: You'll find out lots more if you Google for random wire antenna. I'm sure that not all of it will agree with what I have suggested, but that is often the way with antennas - everybody insists their own recipe is the best.
You can use a superregen to receive CW, but you will need to set the regeneration so that the detector is just oscillating. This oscillation mixes with the incoming signal to produce a beat note in the audio range. You can also demodulate FM with a superegen.
Signs that the superregenerative detector is working: a loud rushing, hissing sound which goes down almost to nothing when a strong signal is detected.
As for more crystals in series or parallel combinations, I think you would be throwing good money after bad, and only whet the oscillator's appetite for more! I realize that this advice may leave you without any oscillator at all, so I will have a think and see what can be done.
Proud Mary, Tue Apr 10 2012, 07:51PM
My encouragement has been directed at the so-called random wire antenna as I think this will be easiest for you to get started with, and can usually produce very satisfactory results for a small outlay. There's a useful blurb about random lengths to avoid here:
You'll find out lots more if you Google for random wire antenna. I'm sure that not all of it will agree with what I have suggested, but that is often the way with antennas - everybody insists their own recipe is the best. You can use a superregen to receive CW, but you will need to set the regeneration so that the detector is just oscillating. This oscillation mixes with the incoming signal to produce a beat note in the audio range. You can also demodulate FM with a superegen.
Signs that the superregenerative detector is working: a loud rushing, hissing sound which goes down almost to nothing when a strong signal is detected.
As for more crystals in series or parallel combinations, I think you would be throwing good money after bad, and only whet the oscillator's appetite for more! I realize that this advice may leave you without any oscillator at all, so I will have a think and see what can be done.
Re: most efficient 80m antenna?
Steve Conner, Tue Apr 10 2012, 08:03PM
Proud Mary is unfortunately right. These single valve transmitter circuits can drive a modern miniature crystal hard enough to shatter it. At least, that's what it says in my ancient RSGB Handbook.
And you can't connect a bunch of crystals in series or parallel. They'll interact and do crazy things.
Steve Conner, Tue Apr 10 2012, 08:03PM
Proud Mary is unfortunately right. These single valve transmitter circuits can drive a modern miniature crystal hard enough to shatter it. At least, that's what it says in my ancient RSGB Handbook.
And you can't connect a bunch of crystals in series or parallel. They'll interact and do crazy things.
Re: most efficient 80m antenna?
alf, Wed Apr 11 2012, 11:13AM
haha okay thx, i'll use like 25m or magnet wire or something xD
ahhh thats cool, haha was worried i'd have to make a different type of rx :P
really, thats good 'cause thats what im hearing :))
i made a colpitts oscillator which oscillates at 3.5mhz, and when i tune the regenerative receiver to that frequency
it becomes silent :D
btw, could the random wire antenna be used to receive with the regen rx without retuning it? :D
ah right maybe i'll make a vfo xD
thanks, Alf.
alf, Wed Apr 11 2012, 11:13AM
Proud Mary wrote ...
My encouragement has been directed at the so-called random wire antenna as I think this will be easiest for you to get started with, and can usually produce very satisfactory results for a small outlay. There's a useful blurb about random lengths to avoid here: You'll find out lots more if you Google for random wire antenna. I'm sure that not all of it will agree with what I have suggested, but that is often the way with antennas - everybody insists their own recipe is the best.
You can use a superregen to receive CW, but you will need to set the regeneration so that the detector is just oscillating. This oscillation mixes with the incoming signal to produce a beat note in the audio range. You can also demodulate FM with a superegen.
Signs that the superregenerative detector is working: a loud rushing, hissing sound which goes down almost to nothing when a strong signal is detected.
As for more crystals in series or parallel combinations, I think you would be throwing good money after bad, and only whet the oscillator's appetite for more! I realize that this advice may leave you without any oscillator at all, so I will have a think and see what can be done.
My encouragement has been directed at the so-called random wire antenna as I think this will be easiest for you to get started with, and can usually produce very satisfactory results for a small outlay. There's a useful blurb about random lengths to avoid here:
You'll find out lots more if you Google for random wire antenna. I'm sure that not all of it will agree with what I have suggested, but that is often the way with antennas - everybody insists their own recipe is the best. You can use a superregen to receive CW, but you will need to set the regeneration so that the detector is just oscillating. This oscillation mixes with the incoming signal to produce a beat note in the audio range. You can also demodulate FM with a superegen.
Signs that the superregenerative detector is working: a loud rushing, hissing sound which goes down almost to nothing when a strong signal is detected.
As for more crystals in series or parallel combinations, I think you would be throwing good money after bad, and only whet the oscillator's appetite for more! I realize that this advice may leave you without any oscillator at all, so I will have a think and see what can be done.
haha okay thx, i'll use like 25m or magnet wire or something xD
ahhh thats cool, haha was worried i'd have to make a different type of rx :P
really, thats good 'cause thats what im hearing :))
i made a colpitts oscillator which oscillates at 3.5mhz, and when i tune the regenerative receiver to that frequency
it becomes silent :D
btw, could the random wire antenna be used to receive with the regen rx without retuning it? :D
ah right maybe i'll make a vfo xD
thanks, Alf.
Re: most efficient 80m antenna?
Proud Mary, Wed Apr 11 2012, 01:38PM
A long wire antenna made of 'magnet wire' - i.e. enamelled copper wire, will work well, if it is thick enough and strong enough and resilient enough, though I wouldn't recommend it. But if it's all you can get just now, it will work for you in the short term.
As for your superregen, just connect the antenna directly to it for the moment. You'll get better results if you have an Antenna Tuning Unit (ATU), between the receiver and the antenna, but this is by no means necessary to start off with.
The EL84 power-oscillator transmitter design is truly awful, Alf, for the following reasons:
1.) In the key-up position, you will have HT on the key itself. This kind of dangerous cathode keying is not acceptable.
2.) Oscillator cathode keying will cause chirp. Chirp is a condition where the oscillator takes a small time to find its feet and settle onto its design frequency - which it will have to do at the beginning of each dit and dah since the oscillator will only be running when you depress the key. At receiving stations, this frequency change mixed with their BFO will sound like a chirp, hence the name. Chirp will be much worse with a keyed VFO.
4. The circuit will destroy most modern crystals, as discussed.
5. A valve oscillator driven hard like this one will produce abundant strong harmonics, which will not be attenuated very much by the output tuning arrangements in this circuit. It will probably interfere with your neighbours' televisions - TVI. Valve oscillators will get up to all kinds of tricks unless you take a very firm hand with them from the outset, from the design stage, where you must specify all the things they must not be allowed to get up to and take account of them.
6. The output matching/tuning set up is unsatisfactory. Besides doing very little to attenuate harmonics and other spurii, it won't make a good job of loading random wires, or anything else outside its obviously limited range.
Proud Mary, Wed Apr 11 2012, 01:38PM
A long wire antenna made of 'magnet wire' - i.e. enamelled copper wire, will work well, if it is thick enough and strong enough and resilient enough, though I wouldn't recommend it. But if it's all you can get just now, it will work for you in the short term.
As for your superregen, just connect the antenna directly to it for the moment. You'll get better results if you have an Antenna Tuning Unit (ATU), between the receiver and the antenna, but this is by no means necessary to start off with.
The EL84 power-oscillator transmitter design is truly awful, Alf, for the following reasons:
1.) In the key-up position, you will have HT on the key itself. This kind of dangerous cathode keying is not acceptable.
2.) Oscillator cathode keying will cause chirp. Chirp is a condition where the oscillator takes a small time to find its feet and settle onto its design frequency - which it will have to do at the beginning of each dit and dah since the oscillator will only be running when you depress the key. At receiving stations, this frequency change mixed with their BFO will sound like a chirp, hence the name. Chirp will be much worse with a keyed VFO.
4. The circuit will destroy most modern crystals, as discussed.
5. A valve oscillator driven hard like this one will produce abundant strong harmonics, which will not be attenuated very much by the output tuning arrangements in this circuit. It will probably interfere with your neighbours' televisions - TVI. Valve oscillators will get up to all kinds of tricks unless you take a very firm hand with them from the outset, from the design stage, where you must specify all the things they must not be allowed to get up to and take account of them.
6. The output matching/tuning set up is unsatisfactory. Besides doing very little to attenuate harmonics and other spurii, it won't make a good job of loading random wires, or anything else outside its obviously limited range.
Re: most efficient 80m antenna?
Sulaiman, Wed Apr 11 2012, 10:01PM
I had a dipole for 20m band (2x 5m) using 0.8mm dia. 'magnet wire' which stayed up for several years, it finally broke so now I use 1.5mm dia 'magnet wire'
The dipole is over 8m high mounted on fiberglass fishing poles which sway easily >30 degrees each way in high wind ... no problem.
So I'd recommend 'magnet wire' for it's cheapness.
I've had trans-atlantic contacts with 50W ssb so it must be ok.
IF you have the space 1/2 wavelength dipoles are the best as no earth is required.
P.S. too thin wire breaks easily and birds may crash into it being unable to see it,
too thick makes an attractive birds resting place,
P.P.S. IF you have conductive soil and make a reasonably good earth then a vertical is good for 80m .. preferably 20m vertical, or less with a matching circuit (AMU/ATU)
If you use a 'long wire' antenna you will also need a good earth for 1/4-wavelength wire, or a good balun for an end-fed 1/2 wavelength, try to get the antenna 1/4 wavelength (or more) above earth or most of the power goes up, not horizontally.
Sulaiman, Wed Apr 11 2012, 10:01PM
I had a dipole for 20m band (2x 5m) using 0.8mm dia. 'magnet wire' which stayed up for several years, it finally broke so now I use 1.5mm dia 'magnet wire'
The dipole is over 8m high mounted on fiberglass fishing poles which sway easily >30 degrees each way in high wind ... no problem.
So I'd recommend 'magnet wire' for it's cheapness.
I've had trans-atlantic contacts with 50W ssb so it must be ok.
IF you have the space 1/2 wavelength dipoles are the best as no earth is required.
P.S. too thin wire breaks easily and birds may crash into it being unable to see it,
too thick makes an attractive birds resting place,
P.P.S. IF you have conductive soil and make a reasonably good earth then a vertical is good for 80m .. preferably 20m vertical, or less with a matching circuit (AMU/ATU)
If you use a 'long wire' antenna you will also need a good earth for 1/4-wavelength wire, or a good balun for an end-fed 1/2 wavelength, try to get the antenna 1/4 wavelength (or more) above earth or most of the power goes up, not horizontally.
Re: most efficient 80m antenna?
alf, Thu Apr 12 2012, 10:45AM
okay... as long as birds dont get tangled in it xD
yeah i have an atu actually so will try it .
oh thats annoying, since i just bought that tube for it lol
im used to receiving painful electric shocks, but the rest of the things you mentioned are a bit of a problem haha
regarding problem number 6, an atu would allow it to work with random wire antennas though right?
so do you think it could be easily modified to work better, without using a different valve haha
thanks , Alf.
alf, Thu Apr 12 2012, 10:45AM
Proud Mary wrote ...
A long wire antenna made of 'magnet wire' - i.e. enamelled copper wire, will work well, if it is thick enough and strong enough and resilient enough, though I wouldn't recommend it. But if it's all you can get just now, it will work for you in the short term.
As for your superregen, just connect the antenna directly to it for the moment. You'll get better results if you have an Antenna Tuning Unit (ATU), between the receiver and the antenna, but this is by no means necessary to start off with.
The EL84 power-oscillator transmitter design is truly awful, Alf, for the following reasons:
1.) In the key-up position, you will have HT on the key itself. This kind of dangerous cathode keying is not acceptable.
2.) Oscillator cathode keying will cause chirp. Chirp is a condition where the oscillator takes a small time to find its feet and settle onto its design frequency - which it will have to do at the beginning of each dit and dah since the oscillator will only be running when you depress the key. At receiving stations, this frequency change mixed with their BFO will sound like a chirp, hence the name. Chirp will be much worse with a keyed VFO.
4. The circuit will destroy most modern crystals, as discussed.
5. A valve oscillator driven hard like this one will produce abundant strong harmonics, which will not be attenuated very much by the output tuning arrangements in this circuit. It will probably interfere with your neighbours' televisions - TVI. Valve oscillators will get up to all kinds of tricks unless you take a very firm hand with them from the outset, from the design stage, where you must specify all the things they must not be allowed to get up to and take account of them.
6. The output matching/tuning set up is unsatisfactory. Besides doing very little to attenuate harmonics and other spurii, it won't make a good job of loading random wires, or anything else outside its obviously limited range.
A long wire antenna made of 'magnet wire' - i.e. enamelled copper wire, will work well, if it is thick enough and strong enough and resilient enough, though I wouldn't recommend it. But if it's all you can get just now, it will work for you in the short term.
As for your superregen, just connect the antenna directly to it for the moment. You'll get better results if you have an Antenna Tuning Unit (ATU), between the receiver and the antenna, but this is by no means necessary to start off with.
The EL84 power-oscillator transmitter design is truly awful, Alf, for the following reasons:
1.) In the key-up position, you will have HT on the key itself. This kind of dangerous cathode keying is not acceptable.
2.) Oscillator cathode keying will cause chirp. Chirp is a condition where the oscillator takes a small time to find its feet and settle onto its design frequency - which it will have to do at the beginning of each dit and dah since the oscillator will only be running when you depress the key. At receiving stations, this frequency change mixed with their BFO will sound like a chirp, hence the name. Chirp will be much worse with a keyed VFO.
4. The circuit will destroy most modern crystals, as discussed.
5. A valve oscillator driven hard like this one will produce abundant strong harmonics, which will not be attenuated very much by the output tuning arrangements in this circuit. It will probably interfere with your neighbours' televisions - TVI. Valve oscillators will get up to all kinds of tricks unless you take a very firm hand with them from the outset, from the design stage, where you must specify all the things they must not be allowed to get up to and take account of them.
6. The output matching/tuning set up is unsatisfactory. Besides doing very little to attenuate harmonics and other spurii, it won't make a good job of loading random wires, or anything else outside its obviously limited range.
okay... as long as birds dont get tangled in it xD
yeah i have an atu actually so will try it .
oh thats annoying, since i just bought that tube for it lol
im used to receiving painful electric shocks, but the rest of the things you mentioned are a bit of a problem haha
regarding problem number 6, an atu would allow it to work with random wire antennas though right?
so do you think it could be easily modified to work better, without using a different valve haha
thanks , Alf.
Re: most efficient 80m antenna?
alf, Thu Apr 12 2012, 10:46AM
20 m vertical... O.o
where d'you get a 20m long pole? xD
right..
but to have birds sitting on it is safe at 10w right? lol
thanks, Alf.
alf, Thu Apr 12 2012, 10:46AM
Sulaiman wrote ...
I had a dipole for 20m band (2x 5m) using 0.8mm dia. 'magnet wire' which stayed up for several years, it finally broke so now I use 1.5mm dia 'magnet wire'
The dipole is over 8m high mounted on fiberglass fishing poles which sway easily >30 degrees each way in high wind ... no problem.
So I'd recommend 'magnet wire' for it's cheapness.
I've had trans-atlantic contacts with 50W ssb so it must be ok.
IF you have the space 1/2 wavelength dipoles are the best as no earth is required.
P.S. too thin wire breaks easily and birds may crash into it being unable to see it,
too thick makes an attractive birds resting place,
P.P.S. IF you have conductive soil and make a reasonably good earth then a vertical is good for 80m .. preferably 20m vertical, or less with a matching circuit (AMU/ATU)
If you use a 'long wire' antenna you will also need a good earth for 1/4-wavelength wire, or a good balun for an end-fed 1/2 wavelength, try to get the antenna 1/4 wavelength (or more) above earth or most of the power goes up, not horizontally.
I had a dipole for 20m band (2x 5m) using 0.8mm dia. 'magnet wire' which stayed up for several years, it finally broke so now I use 1.5mm dia 'magnet wire'
The dipole is over 8m high mounted on fiberglass fishing poles which sway easily >30 degrees each way in high wind ... no problem.
So I'd recommend 'magnet wire' for it's cheapness.
I've had trans-atlantic contacts with 50W ssb so it must be ok.
IF you have the space 1/2 wavelength dipoles are the best as no earth is required.
P.S. too thin wire breaks easily and birds may crash into it being unable to see it,
too thick makes an attractive birds resting place,
P.P.S. IF you have conductive soil and make a reasonably good earth then a vertical is good for 80m .. preferably 20m vertical, or less with a matching circuit (AMU/ATU)
If you use a 'long wire' antenna you will also need a good earth for 1/4-wavelength wire, or a good balun for an end-fed 1/2 wavelength, try to get the antenna 1/4 wavelength (or more) above earth or most of the power goes up, not horizontally.
20 m vertical... O.o
where d'you get a 20m long pole? xD
right..
but to have birds sitting on it is safe at 10w right? lol
thanks, Alf.
Re: most efficient 80m antenna?
Sulaiman, Thu Apr 12 2012, 12:24PM
That's why I said 'preferably 20m vertical, or less with a matching circuit (AMU/ATU)'
16m and 18m fishing poles are available via eBay
mount an 18m pole on a fence post and voila!
More economical 11m and 13m poles are a good choice with an AMU.
and easily made portable.
Since the requirement is an efficient antenna.. (far-field V/m per watt)
1/4-wave vertical or 1/2-wave dipole would be hard to beat.
Don't forget, the launch angle has a really significant effect on long range hf comms (skip etc.)
Sulaiman, Thu Apr 12 2012, 12:24PM
That's why I said 'preferably 20m vertical, or less with a matching circuit (AMU/ATU)'
16m and 18m fishing poles are available via eBay
mount an 18m pole on a fence post and voila!
More economical 11m and 13m poles are a good choice with an AMU.
and easily made portable.
Since the requirement is an efficient antenna.. (far-field V/m per watt)
1/4-wave vertical or 1/2-wave dipole would be hard to beat.
Don't forget, the launch angle has a really significant effect on long range hf comms (skip etc.)
Re: most efficient 80m antenna?
alf, Thu Apr 12 2012, 07:41PM
ahh i get it now xD
i live on the ground floor of a building about 25m high...
if i were to put a 20m long wire from near the roof to the ground, as a 1/4 wave vertical
antenna and use the ground (with an earth rod) as a ground plane would this work? :)
i know the building will kinda block the radio waves at one side though...
this would be an easy solution if it'd work anyway :)
thanks , Alf.
alf, Thu Apr 12 2012, 07:41PM
Sulaiman wrote ...
That's why I said 'preferably 20m vertical, or less with a matching circuit (AMU/ATU)'
16m and 18m fishing poles are available via eBay
mount an 18m pole on a fence post and voila!
More economical 11m and 13m poles are a good choice with an AMU.
and easily made portable.
Since the requirement is an efficient antenna.. (far-field V/m per watt)
1/4-wave vertical or 1/2-wave dipole would be hard to beat.
Don't forget, the launch angle has a really significant effect on long range hf comms (skip etc.)
That's why I said 'preferably 20m vertical, or less with a matching circuit (AMU/ATU)'
16m and 18m fishing poles are available via eBay
mount an 18m pole on a fence post and voila!
More economical 11m and 13m poles are a good choice with an AMU.
and easily made portable.
Since the requirement is an efficient antenna.. (far-field V/m per watt)
1/4-wave vertical or 1/2-wave dipole would be hard to beat.
Don't forget, the launch angle has a really significant effect on long range hf comms (skip etc.)
ahh i get it now xD
i live on the ground floor of a building about 25m high...
if i were to put a 20m long wire from near the roof to the ground, as a 1/4 wave vertical
antenna and use the ground (with an earth rod) as a ground plane would this work? :)
i know the building will kinda block the radio waves at one side though...
this would be an easy solution if it'd work anyway :)
thanks , Alf.
Re: most efficient 80m antenna?
radiotech, Fri Apr 13 2012, 06:26AM
If you can get something metal to rise about 10 meters from a terminal insulator
you can bring it into resonance at 80 meters by connecting a variable coil in series
(variometer) with the bottom.
What is the output configuration of the transmitter? Single terminal, coax connector?
radiotech, Fri Apr 13 2012, 06:26AM
If you can get something metal to rise about 10 meters from a terminal insulator
you can bring it into resonance at 80 meters by connecting a variable coil in series
(variometer) with the bottom.
What is the output configuration of the transmitter? Single terminal, coax connector?
Re: most efficient 80m antenna?
alf, Sat Apr 14 2012, 09:14AM
hmm ive not finished building it yet, but i guess im gonna use a pl-259 socket, so i can connect it to my atu
(kenwood at-230)
but if there is space to put a 20m antenna would this not be more effective than a 10m one?
thx, Alf.
alf, Sat Apr 14 2012, 09:14AM
radiotech wrote ...
If you can get something metal to rise about 10 meters from a terminal insulator
you can bring it into resonance at 80 meters by connecting a variable coil in series
(variometer) with the bottom.
What is the output configuration of the transmitter? Single terminal, coax connector?
If you can get something metal to rise about 10 meters from a terminal insulator
you can bring it into resonance at 80 meters by connecting a variable coil in series
(variometer) with the bottom.
What is the output configuration of the transmitter? Single terminal, coax connector?
hmm ive not finished building it yet, but i guess im gonna use a pl-259 socket, so i can connect it to my atu
(kenwood at-230)
but if there is space to put a 20m antenna would this not be more effective than a 10m one?
thx, Alf.
Re: most efficient 80m antenna?
Sulaiman, Sat Apr 14 2012, 10:05AM
As you have the possibility for a full 1/4-wave antenna go for it,
being near a building will
- de-tune the antenna .. probably less than 20m required for resonance
- potentially cause rfi to your neighbours
- be a little lossy.
If some horizontal space is available mount the bottom of the antenna as far from the building as practical, sloping up towards the top of the building with insulating line (I use fishing line) at the top
Use co-ax (whatever impedance you can get cheaply) to feed the antenna from your rig.
Some means of easily putting the antenna up and down is very helpful for adjusting the length to resonance and repairs.
An AMU/ATU would mean less critical adjustment of antenna length and a wider tuning range.
You will need a good rf earth, a single stake will work but cause losses
an underground metal pipeline (water, sewage etc.) would be much better.
It's quite difficult to make a good rf earth
.... ideally many radials but in practice compromises are required..
1/4 of the fun is the antenna system ... trial and error in my case.
Sulaiman, Sat Apr 14 2012, 10:05AM
As you have the possibility for a full 1/4-wave antenna go for it,
being near a building will
- de-tune the antenna .. probably less than 20m required for resonance
- potentially cause rfi to your neighbours
- be a little lossy.
If some horizontal space is available mount the bottom of the antenna as far from the building as practical, sloping up towards the top of the building with insulating line (I use fishing line) at the top
Use co-ax (whatever impedance you can get cheaply) to feed the antenna from your rig.
Some means of easily putting the antenna up and down is very helpful for adjusting the length to resonance and repairs.
An AMU/ATU would mean less critical adjustment of antenna length and a wider tuning range.
You will need a good rf earth, a single stake will work but cause losses
an underground metal pipeline (water, sewage etc.) would be much better.
It's quite difficult to make a good rf earth
.... ideally many radials but in practice compromises are required..
1/4 of the fun is the antenna system ... trial and error in my case.
Re: most efficient 80m antenna?
alf, Sun Apr 15 2012, 10:20AM
haha cool,
could i use the mains earth?
and could i connect the antenna directly to the atu without coax? :)
thanks for yer help, Alf.
alf, Sun Apr 15 2012, 10:20AM
Sulaiman wrote ...
As you have the possibility for a full 1/4-wave antenna go for it,
being near a building will
- de-tune the antenna .. probably less than 20m required for resonance
- potentially cause rfi to your neighbours
- be a little lossy.
If some horizontal space is available mount the bottom of the antenna as far from the building as practical, sloping up towards the top of the building with insulating line (I use fishing line) at the top
Use co-ax (whatever impedance you can get cheaply) to feed the antenna from your rig.
Some means of easily putting the antenna up and down is very helpful for adjusting the length to resonance and repairs.
An AMU/ATU would mean less critical adjustment of antenna length and a wider tuning range.
You will need a good rf earth, a single stake will work but cause losses
an underground metal pipeline (water, sewage etc.) would be much better.
It's quite difficult to make a good rf earth
.... ideally many radials but in practice compromises are required..
1/4 of the fun is the antenna system ... trial and error in my case.
As you have the possibility for a full 1/4-wave antenna go for it,
being near a building will
- de-tune the antenna .. probably less than 20m required for resonance
- potentially cause rfi to your neighbours
- be a little lossy.
If some horizontal space is available mount the bottom of the antenna as far from the building as practical, sloping up towards the top of the building with insulating line (I use fishing line) at the top
Use co-ax (whatever impedance you can get cheaply) to feed the antenna from your rig.
Some means of easily putting the antenna up and down is very helpful for adjusting the length to resonance and repairs.
An AMU/ATU would mean less critical adjustment of antenna length and a wider tuning range.
You will need a good rf earth, a single stake will work but cause losses
an underground metal pipeline (water, sewage etc.) would be much better.
It's quite difficult to make a good rf earth
.... ideally many radials but in practice compromises are required..
1/4 of the fun is the antenna system ... trial and error in my case.
haha cool,
could i use the mains earth?
and could i connect the antenna directly to the atu without coax? :)
thanks for yer help, Alf.
Re: most efficient 80m antenna?
Sulaiman, Sun Apr 15 2012, 12:12PM
The mains earth will work but it increases the chances of rfi to your neighbours
You can connect your TxRx to an atu without co-ax
You can connect the atu to the antenna with co-ax or a balanced pair or just a single wire with earth local to the atu.
The thing to remember is that any un-balanced line/feeder will form part of the antenna/radiating system, with variable results.
I like the 'purist' approach of resonant antenna and balanced feed-line
but almost any feed/antenna can be matched to the TxRx with an amu.
Roughly speaking, on 80m,
just tune for maximum received noise if and swr meter isn't available.
Just be sure to have a good lpf or bpf on the output to remove spurious transmissions, and a bpf for receive to filter out broadcast stations etc.
BTW, I didn't notice any entry from you in the Amateur Radio thread ... are you licensed?
Sulaiman, Sun Apr 15 2012, 12:12PM
The mains earth will work but it increases the chances of rfi to your neighbours
You can connect your TxRx to an atu without co-ax
You can connect the atu to the antenna with co-ax or a balanced pair or just a single wire with earth local to the atu.
The thing to remember is that any un-balanced line/feeder will form part of the antenna/radiating system, with variable results.
I like the 'purist' approach of resonant antenna and balanced feed-line
but almost any feed/antenna can be matched to the TxRx with an amu.
Roughly speaking, on 80m,
just tune for maximum received noise if and swr meter isn't available.
Just be sure to have a good lpf or bpf on the output to remove spurious transmissions, and a bpf for receive to filter out broadcast stations etc.
BTW, I didn't notice any entry from you in the Amateur Radio thread ... are you licensed?
Re: most efficient 80m antenna?
alf, Sun Apr 15 2012, 06:35PM
ahh right,
i shall connect the tx to the atu with coax, and the antenna to the atu directly (there is a screw connection for long wire antennas)
the atu has an inbuilt swr meter :)
right...
yeah i am i have foundation license, but ive gotta wait till i get intermediate to use homebuilt transmitters xD
haha well i only recently got the license (december 2011), so there is nothing much to say really... :)
thx, Alf.
alf, Sun Apr 15 2012, 06:35PM
Sulaiman wrote ...
The mains earth will work but it increases the chances of rfi to your neighbours
You can connect your TxRx to an atu without co-ax
You can connect the atu to the antenna with co-ax or a balanced pair or just a single wire with earth local to the atu.
The thing to remember is that any un-balanced line/feeder will form part of the antenna/radiating system, with variable results.
I like the 'purist' approach of resonant antenna and balanced feed-line
but almost any feed/antenna can be matched to the TxRx with an amu.
Roughly speaking, on 80m,
just tune for maximum received noise if and swr meter isn't available.
Just be sure to have a good lpf or bpf on the output to remove spurious transmissions, and a bpf for receive to filter out broadcast stations etc.
BTW, I didn't notice any entry from you in the Amateur Radio thread ... are you licensed?
The mains earth will work but it increases the chances of rfi to your neighbours
You can connect your TxRx to an atu without co-ax
You can connect the atu to the antenna with co-ax or a balanced pair or just a single wire with earth local to the atu.
The thing to remember is that any un-balanced line/feeder will form part of the antenna/radiating system, with variable results.
I like the 'purist' approach of resonant antenna and balanced feed-line
but almost any feed/antenna can be matched to the TxRx with an amu.
Roughly speaking, on 80m,
just tune for maximum received noise if and swr meter isn't available.
Just be sure to have a good lpf or bpf on the output to remove spurious transmissions, and a bpf for receive to filter out broadcast stations etc.
BTW, I didn't notice any entry from you in the Amateur Radio thread ... are you licensed?
ahh right,
i shall connect the tx to the atu with coax, and the antenna to the atu directly (there is a screw connection for long wire antennas)
the atu has an inbuilt swr meter :)
right...
yeah i am i have foundation license, but ive gotta wait till i get intermediate to use homebuilt transmitters xD
haha well i only recently got the license (december 2011), so there is nothing much to say really... :)
thx, Alf.
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