Absolutely right! I will certainly give it a try - as soon as I can find the remote switch for the tuner that I have put in a "safe place."sometimes the rules are wrong .
73
Wayne VK4WDM
Using SG-239 Smartuner
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VK4WDM
Re: Using SG-239 Smartuner
73
Wayne VK4WDM
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VK4WDM
Re: Using SG-239 Smartuner
I have done a comparison of vertical vs horizontal loop but I could not do it using the full wave 40m loop because of size constraints, so I used 20m loops.
Both loops were triangular in shape. The horizontal loop was 7.5m at the highest point. One of the corner poles was 6m high, the other 4.5m high. It was fed at the highest with 450ohm "window line" down to the smartuner at the base of the pole and then with coax back to the shack.
The vertical loop was 7.5m high at the apex, 5m high at one end and 6m at the other. and connected directly to the smartuner in the middle of the lowest side. An obvious problem with this configuration was that the low side was only 1m above an iron roof for most of its lenght.
The results were as follows:
40m: No obvious difference in signal strenght in either receive or transmit but the vertical loop was noticably noisier.
30m: As for 40.
20m: Signals 1-2 S points stronger on vertical loop but it was noisier, so no real advantage.
17m: Not enough signals heard for comparison.
15m: As for 20m.
12m: Vertical loop would not tune on this band. Weird - must be some sort of coupling effect with the other antenna, or maybe the roof.
10m: Signals 2-3 S points higher with vertical loop but it was noisier.
6m: Both loops worked equally well.
So in summary, although there was a slight increase in signal strenght with the vertical loop the increased noise negated the advantage. The results might have been different if the vertical loop had been fed at a corner as suggested by Felix VK4FUQ in his article on loops in AR magazine but that was not possible at this QTH. The other possible confounding factor was the difference in radiation pattern between the two loops.
I suggest that a horizontal loop, if possible fed by 450ohm line and auto-tuner, is a good antenna for space and height challenged situations.
73
Wayne VK4WDM
Both loops were triangular in shape. The horizontal loop was 7.5m at the highest point. One of the corner poles was 6m high, the other 4.5m high. It was fed at the highest with 450ohm "window line" down to the smartuner at the base of the pole and then with coax back to the shack.
The vertical loop was 7.5m high at the apex, 5m high at one end and 6m at the other. and connected directly to the smartuner in the middle of the lowest side. An obvious problem with this configuration was that the low side was only 1m above an iron roof for most of its lenght.
The results were as follows:
40m: No obvious difference in signal strenght in either receive or transmit but the vertical loop was noticably noisier.
30m: As for 40.
20m: Signals 1-2 S points stronger on vertical loop but it was noisier, so no real advantage.
17m: Not enough signals heard for comparison.
15m: As for 20m.
12m: Vertical loop would not tune on this band. Weird - must be some sort of coupling effect with the other antenna, or maybe the roof.
10m: Signals 2-3 S points higher with vertical loop but it was noisier.
6m: Both loops worked equally well.
So in summary, although there was a slight increase in signal strenght with the vertical loop the increased noise negated the advantage. The results might have been different if the vertical loop had been fed at a corner as suggested by Felix VK4FUQ in his article on loops in AR magazine but that was not possible at this QTH. The other possible confounding factor was the difference in radiation pattern between the two loops.
I suggest that a horizontal loop, if possible fed by 450ohm line and auto-tuner, is a good antenna for space and height challenged situations.
73
Wayne VK4WDM
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VK3LAJ
Re: Using SG-239 Smartuner
I realise this is a really old thread,
However i've got an SG-239 and im running into some issues.
I've got the tuner at the top of my tower (10m) and for the output i wired it into a so239 for simplicity. that is fed to a small pigtail coax split off to both sides of a random dipole.
Whenever i try and tune up - it sometimes finds a match, other times it goes nuts with SWR and then just locks up requiring power reset.
I tried ferrites on the power lead, using some CAT6 twisted pair cabling for power..
Ideas?
However i've got an SG-239 and im running into some issues.
I've got the tuner at the top of my tower (10m) and for the output i wired it into a so239 for simplicity. that is fed to a small pigtail coax split off to both sides of a random dipole.
Whenever i try and tune up - it sometimes finds a match, other times it goes nuts with SWR and then just locks up requiring power reset.
I tried ferrites on the power lead, using some CAT6 twisted pair cabling for power..
Ideas?
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VK2GOM
Re: Using SG-239 Smartuner
Is this on a certain frequency or frequencies? ie. is the 'going nuts' part common and repeatable to particular frequencies?
Have you got an antenna analyser to look at what the impedance being presented to the tuner is at those frequencies?
You could try and lengthen (or shorten) your dipole, as a test, and see if it still has problems finding a match at the frequencies that were previously a problem.
All these autotuners have a range of impedances they can handle. Outside that range, they could indeed 'go nuts'
73 - Rob VK2GOM / GW0MOH
Have you got an antenna analyser to look at what the impedance being presented to the tuner is at those frequencies?
You could try and lengthen (or shorten) your dipole, as a test, and see if it still has problems finding a match at the frequencies that were previously a problem.
All these autotuners have a range of impedances they can handle. Outside that range, they could indeed 'go nuts'
73 - Rob VK2GOM / GW0MOH
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VK3LAJ
Re: Using SG-239 Smartuner
Some bands it does not even attempt to tune - other bands do tune - then during QSO it trys to retune itself again..
At one point i hate huge RF spikes in the shack, so ive powered it now temp via a battery closer to the tuner.
Currently using no chokes on coax, no baluns,
only have a few ferrites clipped onto the power feed.
At one point i hate huge RF spikes in the shack, so ive powered it now temp via a battery closer to the tuner.
Currently using no chokes on coax, no baluns,
only have a few ferrites clipped onto the power feed.
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VK4WDM
Re: Using SG-239 Smartuner
To VK3LAI
Look up the following article: The SGC230 Smartuner and its use in a balanced antenna configuration by G3YNH. Note the 17m a side length and the use of a "coax choke" (sometimes called an "ugly balun"). Mine is 10 turns of RG213 on 11mm diameter piece of PVC pipe.
Wind a few turns of the power lead to the tuner through a good sized toroid.
How you get it sorted.
73
Wayne VK4WDM
Look up the following article: The SGC230 Smartuner and its use in a balanced antenna configuration by G3YNH. Note the 17m a side length and the use of a "coax choke" (sometimes called an "ugly balun"). Mine is 10 turns of RG213 on 11mm diameter piece of PVC pipe.
Wind a few turns of the power lead to the tuner through a good sized toroid.
How you get it sorted.
73
Wayne VK4WDM
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VK3LAJ
Re: Using SG-239 Smartuner
Thanks Wayne,
I also have another question. On the last page of the manual it shows when used in a dipole configuration to use the bottom earth point instead of the top one.
Does anyone know how its meant to work?
There is Hot and RF ground at the top of the unit, and input hot and input ground at the bottom.
The image indicates to use the input ground, not the top RF ground.
I also have another question. On the last page of the manual it shows when used in a dipole configuration to use the bottom earth point instead of the top one.
Does anyone know how its meant to work?
There is Hot and RF ground at the top of the unit, and input hot and input ground at the bottom.
The image indicates to use the input ground, not the top RF ground.
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