SGC239 Problem

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• I am having a weird problem with my SGC239. I am feeding a Classic dipole (66 ft) 40m to 10 with 450 ladder wire into the 239 and then into coax. The tuner
Message 1 of 11 , Jan 7, 2009
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I am having a weird problem with my SGC239.
I am feeding a Classic dipole (66 ft) 40m to 10 with 450 ladder wire into
the 239 and then into coax. The tuner refuses to hold its tune on 40m. All
other bands (30,20,17,15 and 10), it will tune and hold the tune. On 40, it
will tune; but the minute I start sending, it drops the tune and fluncates
all over the place. Has anyone else experienced this problem?

Thanks and 73

Marty
W8AKS
• Hi Marty, you say your dipole length is 66 feet.  Is that end to end or from the tuner to one end (i.e. each side is 33 feet).  You also say you are using
Message 2 of 11 , Jan 7, 2009
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 Hi Marty,you say your dipole length is 66 feet.  Is that end to end or from the tuner to one end (i.e. each side is 33 feet).  You also say you are using 450 ohms ladder line.Well what you have created is a DOUBLET - and in a doublet the length of the feeder (ladder line) has to be added to the length of each element (from centre to end). So what is the total length from the tuner to each end of the dipole? 73 de  Tom / G0PSE --- On Wed, 7/1/09, Marty Bluhm wrote:From: Marty Bluhm Subject: [Smartuners] SGC239 ProblemTo: Smartuners@yahoogroups.comDate: Wednesday, 7 January, 2009, 4:06 PM```I am having a weird problem with my SGC239. I am feeding a Classic dipole (66 ft) 40m to 10 with 450 ladder wire into the 239 and then into coax. The tuner refuses to hold its tune on 40m. All other bands (30,20,17,15 and 10), it will tune and hold the tune. On 40, it will tune; but the minute I start sending, it drops the tune and fluncates all over the place. Has anyone else experienced this problem? Thanks and 73 Marty W8AKS ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Smartuners/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Smartuners/join (Yahoo! ID required) <*> To change settings via email: mailto:Smartuners-digest@yahoogroups.com mailto:Smartuners-fullfeatured@yahoogroups.com <*> To unsubscribe from this group, send an email to: Smartuners-unsubscribe@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/ ```
• ok, that may be the problem. I dont know the length of the feedline right offhand. But I m willing to bet that I have to shorten the feedline after I measure
Message 3 of 11 , Jan 7, 2009
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ok, that may be the problem. I dont know the length of the feedline right offhand. But I'm willing to bet that I have to shorten the feedline after I measure it. Oh yes, the antenna itself is 66ft end to end. It was cut for 40m. This is the old classic dipole article from QST many years ago and in the antenna books.

Snowing right now, so will have to wait a bit. Will let the group know the outcome.

Thanks for the help
73
Marty
W8AKS

-----Original Message-----
From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com]On Behalf Of THOMAS TAYLOR
Sent: Wednesday, January 07, 2009 18:51
To: Smartuners@yahoogroups.com
Subject: Re: [Smartuners] SGC239 Problem

 Hi Marty,you say your dipole length is 66 feet.  Is that end to end or from the tuner to one end (i.e. each side is 33 feet).  You also say you are using 450 ohms ladder line.Well what you have created is a DOUBLET - and in a doublet the length of the feeder (ladder line) has to be added to the length of each element (from centre to end). So what is the total length from the tuner to each end of the dipole? 73 de  Tom / G0PSE--- On Wed, 7/1/09, Marty Bluhm wrote:From: Marty Bluhm Subject: [Smartuners] SGC239 ProblemTo: Smartuners@yahoogro ups.comDate: Wednesday, 7 January, 2009, 4:06 PM```I am having a weird problem with my SGC239. I am feeding a Classic dipole (66 ft) 40m to 10 with 450 ladder wire into the 239 and then into coax. The tuner refuses to hold its tune on 40m. All other bands (30,20,17,15 and 10), it will tune and hold the tune. On 40, it will tune; but the minute I start sending, it drops the tune and fluncates all over the place. Has anyone else experienced this problem? Thanks and 73 Marty W8AKS ------------ --------- --------- ------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups. yahoo.com/ group/Smartuners / <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups. yahoo.com/ group/Smartuners /join (Yahoo! ID required) <*> To change settings via email: mailto:Smartuners- digest@yahoogrou ps.com mailto:Smartuners- fullfeatured@ yahoogroups. com <*> To unsubscribe from this group, send an email to: Smartuners-unsubscr ibe@yahoogroups. com <*> Your use of Yahoo! Groups is subject to: http://docs. yahoo.com/ info/terms/ ```

• Hi Marty,   When you measure the length of your ladder line feeder, add it to the 33 feet of the half of your dipole.  The combined length has to fall
Message 4 of 11 , Jan 7, 2009
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 Hi Marty, When you measure the length of your ladder line feeder, add it to the 33 feet of the half of your dipole.  The combined length has to fall within the following parameters : 70 - 82 ft,  92 - 98 ft,,  105 - 113 ft, 140 - 148 ft  There is no mystery to this.  The antenna you have made is a Doublet.  A doublet is simply two inverted 'L's.   An inverted L is in effect a long wire. Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above are  recommended lengths for long wire antennas which will resonate on all amateur bands. I suspect the present length of your feeder added to 33 feet would conflict with this rule for40 metres. 73 de Tom / G0PSETom Taylor
• Agree wholeheartly Tom, running an inverted L on 160m; but to be honest, hadnt looked at the classic dipole in that sense; but now that you pointed it out,
Message 5 of 11 , Jan 7, 2009
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Agree wholeheartly Tom, running an inverted L on 160m; but to be honest, hadnt looked at the classic dipole in that sense; but now that you pointed it out, it's right there. Right now, we have 2 i n of snow on the ground and it is still coming down in WV. Supposed to do this for the next couple days, dont know when I'll get to work on it. Will let you know how I make out. Thanks for all the help, really appreciate it. It was driving me up the wall, not it doesnt take much <grin>

73
Marty
W8AKS

-----Original Message-----
From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com]On Behalf Of THOMAS TAYLOR
Sent: Wednesday, January 07, 2009 23:46
To: Smartuners@yahoogroups.com
Subject: RE: [Smartuners] SGC239 Problem

 Hi Marty, When you measure the length of your ladder line feeder, add it to the 33 feet of the half of your dipole.  The combined length has to fall within the following parameters : 70 - 82 ft,  92 - 98 ft,,  105 - 113 ft, 140 - 148 ft  There is no mystery to this.  The antenna you have made is a Doublet.  A doublet is simply two inverted 'L's.   An inverted L is in effect a long wire. Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above are  recommended lengths for long wire antennas which will resonate on all amateur bands. I suspect the present length of your feeder added to 33 feet would conflict with this rule for40 metres. 73 de Tom / G0PSETom Taylor

• Hi Tom, I beg to differ, but a doublet fed with ladder line is not the same as two inverted L’s, Balanced feeder behaves in a very different manner, you are
Message 6 of 11 , Jan 8, 2009
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Hi Tom,

I beg to differ, but a doublet fed with ladder line is not the same as two inverted L’s, Balanced feeder behaves in a very different manner, you are correct in that the length of the ladder line may play a part in the impedance matching however this is due to the fact that the impedance along the ladder line will change along it’s length if the antenna does not match it’s characteristic impedance at it’s feed point (450 ohm). If the antenna has an impedance of 450 ohm’s at the feed point, it will maintain the 450 ohm along the length of the ladder line regardless of the length of ladder line. This obviously will change depending on element length and frequency, but it will behave differently to an Inverted L.

Marty,

This sounds more like RF getting into the tuner, the fact that you can get a tune suggests that it is not a problem with the antenna its self (the SGC auto tuners can give a tune on most bands on an amazing range of antennas). I have experienced similar problems using my SG-230 on a 35m long doublet fed with 300 ohm balanced feeder, I could get a tune on all bands, but on 160m when I started transmitting it would suddenly loose the tune, it turned out to be RF getting into the tuner and causing it problems (got in through a long 12v cable powering the unit, some clip on ferrites sorted it).

73 James M3YOM

From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com] On Behalf Of THOMAS TAYLOR
Sent: 07 January 2009 23:46
To: Smartuners@yahoogroups.com
Subject: RE: [Smartuners] SGC239 Problem

 Hi Marty, When you measure the length of your ladder line feeder, add it to the 33 feet of the half of your dipole.  The combined length has to fall within the following parameters : 70 - 82 ft,  92 - 98 ft,,  105 - 113 ft, 140 - 148 ft  There is no mystery to this.  The antenna you have made is a Doublet.  A doublet is simply two inverted 'L's.   An inverted L is in effect a long wire. Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above are  recommended lengths for long wire antennas which will resonate on all amateur bands. I suspect the present length of your feeder added to 33 feet would conflict with this rule for40 metres. 73 de Tom / G0PSETom Taylor

• ... Unless it’s an SG230! So far, I’ve never had a problem with half-wavelengths. To be on the safe side, one could chop out a few feet though. ... No. In
Message 7 of 11 , Jan 9, 2009
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>>> Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof )

Unless it’s an SG230! So far, I’ve never had a problem with half-wavelengths. To be on the safe side, one could chop out a few feet though.

>>> A doublet is simply two inverted 'L's

No. In terms of construction it sort of looks like this, but electrically it’s not. It’s a dipole fed with ladder line or open wire feeder. The feeder in a doublet (dipole) won't resonate whereas the vertical section of an inverted L will.

Callum McCormick
http://www.m0mcx.co.uk/
• Hi Jim, you hit the nail on the head. I had an extra long 12v line going from the wall wart (RS 12V) to the 239. I wrapped it through a ferrite choke and my
Message 8 of 11 , Jan 9, 2009
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﻿
Hi Jim, you hit the nail on the head. I had an extra long 12v line going from the wall wart (RS 12V)  to the 239. I wrapped  it through a ferrite choke and my problem went away. Thank you very much.
73
Marty
W8AKS

-----Original Message-----
From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com]On Behalf Of James Thresher
Sent: Thursday, January 08, 2009 22:08
To: 'Smartuners@yahoogroups.com'
Subject: RE: [Smartuners] SGC239 Problem

Hi Tom,

I beg to differ, but a doublet fed with ladder line is not the same as two inverted L’s, Balanced feeder behaves in a very different manner, you are correct in that the length of the ladder line may play a part in the impedance matching however this is due to the fact that the impedance along the ladder line will change along it’s length if the antenna does not match it’s characteristic impedance at it’s feed point (450 ohm). If the antenna has an impedance of 450 ohm’s at the feed point, it will maintain the 450 ohm along the length of the ladder line regardless of the length of ladder line. This obviously will change depending on element length and frequency, but it will behave differently to an Inverted L.

Marty,

This sounds more like RF getting into the tuner, the fact that you can get a tune suggests that it is not a problem with the antenna its self (the SGC auto tuners can give a tune on most bands on an amazing range of antennas). I have experienced similar problems using my SG-230 on a 35m long doublet fed with 300 ohm balanced feeder, I could get a tune on all bands, but on 160m when I started transmitting it would suddenly loose the tune, it turned out to be RF getting into the tuner and causing it problems (got in through a long 12v cable powering the unit, some clip on ferrites sorted it).

73 James M3YOM

From: Smartuners@yahoogro ups.com [mailto:Smartuners@ yahoogroups. com] On Behalf Of THOMAS TAYLOR
Sent: 07 January 2009 23:46
To: Smartuners@yahoogro ups.com
Subject: RE: [Smartuners] SGC239 Problem

 Hi Marty,When you measure the length of your ladder line feeder, add it to the 33 feet of the half of your dipole.  The combined length has to fall within the following parameters :70 - 82 ft,  92 - 98 ft,,  105 - 113 ft, 140 - 148 ft There is no mystery to this.  The antenna you have made is a Doublet.  A doublet is simply two inverted 'L's.   An inverted L is in effect a long wire. Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above are  recommended lengths for long wire antennas which will resonate on all amateur bands.I suspect the present length of your feeder added to 33 feet would conflict with this rule for40 metres.73 de Tom / G0PSETom Taylor

• Hi Marty, I’m glad you sorted the problem, in most cases with the SGC Autotuners it is rarely the antenna at fault (usually RF problems). 73 James M3YOM
Message 9 of 11 , Jan 10, 2009
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Hi Marty,

I’m glad you sorted the problem, in most cases with the SGC Autotuners it is rarely the antenna at fault (usually RF problems).

73 James M3YOM

From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com] On Behalf Of Marty Bluhm
Sent: 10 January 2009 03:47
To: Smartuners@yahoogroups.com
Subject: RE: [Smartuners] SGC239 Problem

﻿

Hi Jim, you hit the nail on the head. I had an extra long 12v line going from the wall wart (RS 12V)  to the 239. I wrapped  it through a ferrite choke and my problem went away. Thank you very much.

73

Marty

W8AKS

-----Original Message-----
From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com]On Behalf Of James Thresher
Sent: Thursday, January 08, 2009 22:08
To: 'Smartuners@yahoogroups.com'
Subject: RE: [Smartuners] SGC239 Problem

Hi Tom,

I beg to differ, but a doublet fed with ladder line is not the same as two inverted L’s, Balanced feeder behaves in a very different manner, you are correct in that the length of the ladder line may play a part in the impedance matching however this is due to the fact that the impedance along the ladder line will change along it’s length if the antenna does not match it’s characteristic impedance at it’s feed point (450 ohm). If the antenna has an impedance of 450 ohm’s at the feed point, it will maintain the 450 ohm along the length of the ladder line regardless of the length of ladder line. This obviously will change depending on element length and frequency, but it will behave differently to an Inverted L.

Marty,

This sounds more like RF getting into the tuner, the fact that you can get a tune suggests that it is not a problem with the antenna its self (the SGC auto tuners can give a tune on most bands on an amazing range of antennas). I have experienced similar problems using my SG-230 on a 35m long doublet fed with 300 ohm balanced feeder, I could get a tune on all bands, but on 160m when I started transmitting it would suddenly loose the tune, it turned out to be RF getting into the tuner and causing it problems (got in through a long 12v cable powering the unit, some clip on ferrites sorted it).

73 James M3YOM

From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com] On Behalf Of THOMAS TAYLOR
Sent: 07 January 2009 23:46
To: Smartuners@yahoogroups.com
Subject: RE: [Smartuners] SGC239 Problem

 Hi Marty,When you measure the length of your ladder line feeder, add it to the 33 feet of the half of your dipole.  The combined length has to fall within the following parameters :70 - 82 ft,  92 - 98 ft,,  105 - 113 ft, 140 - 148 ft There is no mystery to this.  The antenna you have made is a Doublet.  A doublet is simply two inverted 'L's.   An inverted L is in effect a long wire. Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above are  recommended lengths for long wire antennas which will resonate on all amateur bands.I suspect the present length of your feeder added to 33 feet would conflict with this rule for40 metres.73 de Tom / G0PSETom Taylor

• Only an idiot would think the feedline, if properly installed radiate. Length of the same has to do with proper impedance matching, NOT resonance! Chairman
Message 10 of 11 , Oct 20 7:20 AM
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Only an idiot would think the feedline, if properly installed radiate. Length of the same has to do with proper impedance matching, NOT resonance! Chairman Tom, extensive investigations have shown you to be wrong...AGAIN!

--- In Smartuners@yahoogroups.com, THOMAS TAYLOR <thomas.taylor19@...> wrote:
>
> Hi Marty,
> Â
> When you measure the length of your ladder line feeder, add it to theÂ 33 feet of the half of your dipole.Â  The combined length has to fall within the following parameters :
> Â
> 70 - 82 ft,Â Â 92 - 98 ft,,Â  105 - 113 ft, 140 - 148 ftÂ
> Â
> There is no mystery to this.Â  The antenna you have made is a Doublet.Â  A doublet is simply two inverted 'L's.Â Â  An inverted L is in effect a long wire.Â
> Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above areÂ  recommended lengths for long wire antennas which will resonate on all amateur bands.
> Â
> I suspect the present length of your feeder added to 33 feet would conflict with this rule for
> 40 metres.
> Â
> 73 de Tom / G0PSE
>
>
>
> Tom Taylor
>
• Hi boys, Moderator Dave here. Watching this thread to be sure it continues forward in a gentlemen-like manner. Thanks, David H. Hatch - N9ZRT dave@oslc-gb.org
Message 11 of 11 , Oct 20 8:55 AM
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Hi boys,

Moderator Dave here.

Watching this thread to be sure it continues forward in a gentlemen-like manner.

Thanks,

David H. Hatch - N9ZRT

On Oct 20, 2010, at 9:20 AM, navyroyal53 wrote:

Only an idiot would think the feedline, if properly installed radiate. Length of the same has to do with proper impedance matching, NOT resonance! Chairman Tom, extensive investigations have shown you to be wrong...AGAIN!

--- In Smartuners@yahoogroups.com, THOMAS TAYLOR <thomas.taylor19@...> wrote:
>
> Hi Marty,
> Â
> When you measure the length of your ladder line feeder, add it to theÂ 33 feet of the half of your dipole.Â  The combined length has to fall within the following parameters :
> Â
> 70 - 82 ft,Â Â 92 - 98 ft,,Â  105 - 113 ft, 140 - 148 ftÂ
> Â
> There is no mystery to this.Â  The antenna you have made is a Doublet.Â  A doublet is simply two inverted 'L's.Â Â  An inverted L is in effect a long wire.Â
> Remembering the rule of Auto ATUs that long wire antennas must avoid half-wave lengths (or multiples thereof ) of the working frequency, the lengths above areÂ  recommended lengths for long wire antennas which will resonate on all amateur bands.
> Â
> I suspect the present length of your feeder added to 33 feet would conflict with this rule for
> 40 metres.
> Â
> 73 de Tom / G0PSE
>
>
>
> Tom Taylor
>

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