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#1
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Hi Ian,
Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes Hi Richard, Just an update for you on my AT1KP tuner. I am only running 110 watts through the tuner due to not owning an Amplifier. I have tried it out on an End Fed wire WITH an earth ground rod that has a very poor ground and also an End Fed Zep. It still tunes these wires down to 1.1:1 from 160 - 6 Meters with ease. I am very pleased with it and I'm glade I purchased the AT1KP. Hope this helps. 73 Andy -- Ian |
#2
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In message , Andy
writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the twin feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian |
#3
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Ian,
I'll have to do some experimenting with the 300 Ohm feeder and see what happens. The End Fed on 40m is very poor indeed. I would say unusable like it is. The End Fed wire at the moment is resonate on 2. 682 MHz. The funny thing is that when I cut the wire to bring the End Fed to resonate on 80m, no matter how much wire I cut off it doesn't really move from the 2.682 MHz. I have tried this with and with out the ribbon feeder being in place and with coax connected direct and the braid connected to the earth rod. What would cause this? I have no problem using the Analyser with my mobile and centre fed dipoles. 73 Andy "Ian Jackson" wrote in message ... In message , Andy writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the twin feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian |
#4
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Andy wrote:
Ian, I'll have to do some experimenting with the 300 Ohm feeder and see what happens. The End Fed on 40m is very poor indeed. I would say unusable like it is. The End Fed wire at the moment is resonate on 2. 682 MHz. The funny thing is that when I cut the wire to bring the End Fed to resonate on 80m, no matter how much wire I cut off it doesn't really move from the 2.682 MHz. I have tried this with and with out the ribbon feeder being in place and with coax connected direct and the braid connected to the earth rod. What would cause this? I have no problem using the Analyser with my mobile and centre fed dipoles. 73 Andy "Ian Jackson" wrote in message ... In message , Andy writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the twin feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian adding a suitably cut wire counterpoise at +% for each band should certainly assist things . |
#5
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In message , atec77
writes Andy wrote: "Ian Jackson" wrote in message ... In message , Andy writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian Ian, I'll have to do some experimenting with the 300 Ohm feeder and see what happens. The End Fed on 40m is very poor indeed. I would say unusable like it is. The End Fed wire at the moment is resonate on 2. 682 MHz. The funny thing is that when I cut the wire to bring the End Fed to resonate on 80m, no matter how much wire I cut off it doesn't really move from the 2.682 MHz. I have tried this with and with out the ribbon feeder being in place and with coax connected direct and the braid connected to the earth rod. What would cause this? I have no problem using the Analyser with my mobile and centre fed dipoles. 73 Andy adding a suitably cut wire counterpoise at +% for each band should certainly assist things . I rather think that Andy can't add counterpoises. A decent earthing system should work (although additional counterpoises certainly won't do any harm). Re the 2.682MHz resonance, this may be because the coax is completely mismatched at lots of frequencies, and what you're seeing this is more-or-less a spurious resonance of the coax itself. Do you still get it with the wire completely disconnected? Even with centre-fed dipoles, you often get some very unexpected resonances way off frequency (especially of you are doing a wideband frequency sweep of the return loss / SWR). As I said previously, persuading an approximate halfwave endfed (which is what you have on 40m) to work with a coax feed is certainly not ideal, but you can usually get it to work fairly well (with all the provisos already discussed). My setup here is almost twice the size of what you have, so the wire feed impedance will be low on 160m and I high on 80m and 40m. 80m (corresponding to your 40m) is certainly lively enough. On 40m, the performance does not seem to be unduly poor compared with the signal reports swapped between others on the band. So, Andy, I simply don't know why your 40m is so poor. Have you tried (temporarily) reducing the length to around 33 feet, so that it is a quarterwave on 40m? This should give a reasonable match for your coax (at least, nothing you can't tune out back in the shack). If this is more lively than the 64 feet, maybe you can try two wires in parallel. This can be discussed later if the 33 feet shows promise. If a multiband (and possibly compromise) aerial doesn't work well, it's a good idea to try something simple which you know SHOULD work. The problem may lie elsewhere. Finally, can I ask you to follow the standard practice of bottom posting! Cheers... -- Ian |
#6
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Ian Jackson wrote:
In message , atec77 writes Andy wrote: "Ian Jackson" wrote in message ... In message , Andy writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian Ian, I'll have to do some experimenting with the 300 Ohm feeder and see what happens. The End Fed on 40m is very poor indeed. I would say unusable like it is. The End Fed wire at the moment is resonate on 2. 682 MHz. The funny thing is that when I cut the wire to bring the End Fed to resonate on 80m, no matter how much wire I cut off it doesn't really move from the 2.682 MHz. I have tried this with and with out the ribbon feeder being in place and with coax connected direct and the braid connected to the earth rod. What would cause this? I have no problem using the Analyser with my mobile and centre fed dipoles. 73 Andy adding a suitably cut wire counterpoise at +% for each band should certainly assist things . I rather think that Andy can't add counterpoises. of course he can , he has a run of crap coax so when he replaces it with some rg213 adding some multi strand suitably trimmed one be a burden from the far coax connection back A decent earthing system should work maybe there is a reason to not have one , with more description a balun of some sort may prove most useful (although additional counterpoises certainly won't do any harm). Re the 2.682MHz resonance, this may be because the coax is completely mismatched at lots of frequencies, and what you're seeing this is more-or-less a spurious resonance of the coax itself. rg 58cu ? is kinda crap ![]() Do you still get it with the wire completely disconnected? Even with centre-fed dipoles, you often get some very unexpected resonances way off frequency (especially of you are doing a wideband frequency sweep of the return loss / SWR). As I said previously, persuading an approximate halfwave endfed (which is what you have on 40m) to work with a coax feed is certainly not ideal, but you can usually get it to work fairly well (with all the provisos already discussed). My setup here is almost twice the size of what you have, so the wire feed impedance will be low on 160m and I high on 80m and 40m. 80m (corresponding to your 40m) is certainly lively enough. On 40m, the performance does not seem to be unduly poor compared with the signal reports swapped between others on the band. So, Andy, I simply don't know why your 40m is so poor. Have you tried (temporarily) reducing the length to around 33 feet, so that it is a quarterwave on 40m? This should give a reasonable match for your coax (at least, nothing you can't tune out back in the shack). If this is more lively than the 64 feet, maybe you can try two wires in parallel. This can be discussed later if the 33 feet shows promise. If a multiband (and possibly compromise) aerial doesn't work well, it's a good idea to try something simple which you know SHOULD work. The problem may lie elsewhere. Oh dear Finally, can I ask you to follow the standard practice of bottom posting! Cheers... |
#7
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Oh, I think under the circumstances, that RG-58 isn't all that bad.
May not have the lowest losses possible, but certainly not complete 'crap'. Replacing it with something 'better' is certainly an option, but not the first one I'd try. Options. Try all that you can think of and see what happens. If things are 'better' on one particular band doing it 'this' way, then I think I'd note that when using that particular band. Repeat for the other bands. Lots of work? Sure, but if it works, it works. Finding one antenna that does it all is almost impossible. Too many variables depending on each individual installation. But, if you get 'close', that's probably as good as you can expect, depending on the circumstances. Having the absolute 'best' antenna in the world is certainly nice! It isn't absolutely necessary. Everyone goes through this same sort of thingy. The results differ, but so do the circumstances. Good luck. - 'Doc |
#8
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![]() "Ian Jackson" wrote in message ... In message , atec77 writes Andy wrote: "Ian Jackson" wrote in message ... In message , Andy writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian Ian, I'll have to do some experimenting with the 300 Ohm feeder and see what happens. The End Fed on 40m is very poor indeed. I would say unusable like it is. The End Fed wire at the moment is resonate on 2. 682 MHz. The funny thing is that when I cut the wire to bring the End Fed to resonate on 80m, no matter how much wire I cut off it doesn't really move from the 2.682 MHz. I have tried this with and with out the ribbon feeder being in place and with coax connected direct and the braid connected to the earth rod. What would cause this? I have no problem using the Analyser with my mobile and centre fed dipoles. 73 Andy adding a suitably cut wire counterpoise at +% for each band should certainly assist things . I rather think that Andy can't add counterpoises. A decent earthing system should work (although additional counterpoises certainly won't do any harm). Re the 2.682MHz resonance, this may be because the coax is completely mismatched at lots of frequencies, and what you're seeing this is more-or-less a spurious resonance of the coax itself. Do you still get it with the wire completely disconnected? Even with centre-fed dipoles, you often get some very unexpected resonances way off frequency (especially of you are doing a wideband frequency sweep of the return loss / SWR). As I said previously, persuading an approximate halfwave endfed (which is what you have on 40m) to work with a coax feed is certainly not ideal, but you can usually get it to work fairly well (with all the provisos already discussed). My setup here is almost twice the size of what you have, so the wire feed impedance will be low on 160m and I high on 80m and 40m. 80m (corresponding to your 40m) is certainly lively enough. On 40m, the performance does not seem to be unduly poor compared with the signal reports swapped between others on the band. So, Andy, I simply don't know why your 40m is so poor. Have you tried (temporarily) reducing the length to around 33 feet, so that it is a quarterwave on 40m? This should give a reasonable match for your coax (at least, nothing you can't tune out back in the shack). If this is more lively than the 64 feet, maybe you can try two wires in parallel. This can be discussed later if the 33 feet shows promise. If a multiband (and possibly compromise) aerial doesn't work well, it's a good idea to try something simple which you know SHOULD work. The problem may lie elsewhere. Finally, can I ask you to follow the standard practice of bottom posting! Cheers... -- Ian I've have just connected the Analyser at the feed point on the End fed wire. The frequency is now at 2.898 MHz without coax being in line. I have just tried to shorten the Antenna again to bring the frequency closer to the 80m band, but it will not adjust from this frequency. What's confusing me is that the End fed wire should be longer than a 1/4 wave on 80 and the frequency that it ended up on, that is now 2.898 would be about right for the length. So why won't that frequency change when I start trimming the wire down in size? It just isn't making any sense to me. The resonant frequency surely should change with the altered length. 73 Andy |
#9
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In message , Andy
writes "Ian Jackson" wrote in message ... In message , atec77 writes Andy wrote: "Ian Jackson" wrote in message ... In message , Andy writes "Ian Jackson" wrote in message ... Andy, is your endfed wire the one in your other thread of the 8th June (ie the 80 Meter End Fed, fed with coax at the far end)? If so, presumably the tuner is at the shack end. Or are you feeding it from the shack end. In message , Andy writes -- Hi Ian, Yes its the same. The tuner is at the shack end (house) and I'm feeding the antenna with 50 Ohm RG-58 C/U coax at the far end of the garden. If I can get it working well I will replace it with some RG-213 that I have here. I put it back up yesterday and started experimenting again. The End Fed at the moment has 15 feet of 300 Ohm slotted ribbon feeder. This is all I had left spare. One side is connected to the wire antenna and the other side left, not connected. The coax is connected to the 300 Ohm at the bottom and the braid side is now connected to the unconnected side of the 300 Ohm and also to the earth ground rod. On 80 the receive is up 2-4 S points compared with the 40m coax Centre Fed Dipole. I have not had chance to get any actual reports on 80 yet. Maybe this weekend. 73 Andy OK, Andy. Noted. I don't know if you will really improve things by using the 15 foot of 300 ohm feeder. It's a sort of a zepp, but with one side of the feeder earthed. I would try disconnecting the earthed ('unconnected') side from earth / coax braid. You can either leave it floating, or connect it to the coax inner. It will then be approximately a quarterwave on 20m, fed in parallel with the long wire. Don't read too much into the excellent SWR you're getting with the tuner. That's what the TX sees, but the tuner can't affect the SWR on the aerial feeder. If the coax SWR is sky high (and it can be if the impedance at aerial feed point is high), the coax losses will be much more that you would get compared with when it is matched correctly. You only get away with it by using the lowest-loss you can find, and keeping the coax as short as possible. I'm not surprised that 80m on the endfed is a bit better than the 40m dipole. But what's 40m like on the endfed? That's when the feed impedance (and coax SWR) will be very high, and where the RG-213 might perform better noticeably better than the RG-58. As I think I said before, although I am an advocate of simply using coax (regardless), after all these years I am considering in investing in something like a SG230 remote tuner for the far end of the coax. -- Ian Ian, I'll have to do some experimenting with the 300 Ohm feeder and see what happens. The End Fed on 40m is very poor indeed. I would say unusable like it is. The End Fed wire at the moment is resonate on 2. 682 MHz. The funny thing is that when I cut the wire to bring the End Fed to resonate on 80m, no matter how much wire I cut off it doesn't really move from the 2.682 MHz. I have tried this with and with out the ribbon feeder being in place and with coax connected direct and the braid connected to the earth rod. What would cause this? I have no problem using the Analyser with my mobile and centre fed dipoles. 73 Andy adding a suitably cut wire counterpoise at +% for each band should certainly assist things . I rather think that Andy can't add counterpoises. A decent earthing system should work (although additional counterpoises certainly won't do any harm). Re the 2.682MHz resonance, this may be because the coax is completely mismatched at lots of frequencies, and what you're seeing this is more-or-less a spurious resonance of the coax itself. Do you still get it with the wire completely disconnected? Even with centre-fed dipoles, you often get some very unexpected resonances way off frequency (especially of you are doing a wideband frequency sweep of the return loss / SWR). As I said previously, persuading an approximate halfwave endfed (which is what you have on 40m) to work with a coax feed is certainly not ideal, but you can usually get it to work fairly well (with all the provisos already discussed). My setup here is almost twice the size of what you have, so the wire feed impedance will be low on 160m and I high on 80m and 40m. 80m (corresponding to your 40m) is certainly lively enough. On 40m, the performance does not seem to be unduly poor compared with the signal reports swapped between others on the band. So, Andy, I simply don't know why your 40m is so poor. Have you tried (temporarily) reducing the length to around 33 feet, so that it is a quarterwave on 40m? This should give a reasonable match for your coax (at least, nothing you can't tune out back in the shack). If this is more lively than the 64 feet, maybe you can try two wires in parallel. This can be discussed later if the 33 feet shows promise. If a multiband (and possibly compromise) aerial doesn't work well, it's a good idea to try something simple which you know SHOULD work. The problem may lie elsewhere. Finally, can I ask you to follow the standard practice of bottom posting! Cheers... -- Ian I've have just connected the Analyser at the feed point on the End fed wire. The frequency is now at 2.898 MHz without coax being in line. I have just tried to shorten the Antenna again to bring the frequency closer to the 80m band, but it will not adjust from this frequency. Ummmm... Obviously something is wrong. It looks like your analyser is simply telling lies. Could it have a spurious resonance at this frequency? What's confusing me is that the End fed wire should be longer than a 1/4 wave on 80 and the frequency that it ended up on, that is now 2.898 would be about right for the length. A quarterwave on 80m is around 66 feet. Your 63 feet is actually a bit on the short side. Being only 20 feet up may pull the resonance a bit lower, but I doubt is could be anywhere as low as 2.898MHz. So why won't that frequency change when I start trimming the wire down in size? It just isn't making any sense to me. The resonant frequency surely should change with the altered length. If shortening the aerial doesn't change the frequency, I don't think your analyser is measuring the aerial. This is indeed a puzzle. As I suggested before, you could go from the sublime to the ridiculous, and try something like 33 feet, which should resonate at around 7MHz. If it sticks at 2.898MHz, something is seriously amiss. -- Ian |
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