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Old June 20th 08, 02:24 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Apr 2008
Posts: 71
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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



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Old June 20th 08, 04:31 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Nov 2007
Posts: 568
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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
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Old June 22nd 08, 10:06 AM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Apr 2008
Posts: 71
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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   Report Post  
Old June 22nd 08, 11:11 AM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jun 2008
Posts: 3
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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   Report Post  
Old June 22nd 08, 12:45 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Nov 2007
Posts: 568
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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   Report Post  
Old June 22nd 08, 02:34 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jun 2008
Posts: 3
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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   Report Post  
Old June 22nd 08, 03:26 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Nov 2007
Posts: 157
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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   Report Post  
Old June 22nd 08, 06:13 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Apr 2008
Posts: 71
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner


"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   Report Post  
Old June 22nd 08, 07:35 PM posted to aus.radio.amateur.misc,rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Nov 2007
Posts: 568
Default PALSTAR AT1KP Meter 1200 Watt Antenna Tuner

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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