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Author Topic: Auto Tuners Vs Manual Tuners  (Read 3948 times)
KD2CJJ
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Posts: 369




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« on: May 10, 2013, 01:59:21 PM »

Hi,

I have a LDG Auto Tuner AT 100 PRO II - it has worked very well for me... Unfortunately the bandwidth of my antenna is very narrow (mini beam) and on top of that where I have my antenna depending on the direction its pointing half of the antenna is over my house and the other half is not.  In other words, the tuner is getting a workout and some times not needfully!    Even when i have not changed the frequency a full  auto tune is forced which is almost like doing a manual tune since I am using the RF sensing feature of the tuner (lower wattage to 10 watts, switch to CW, send carrier, wait a few seconds for tune) Is is a major issue?  Definatley NOT!

with that said... I am looking into getting an Amp thus will start looking for a good high power tuner first.

So the question is, do I go for another auto tuner like the LDG 1000 OR do I go for a good manual tuner... 

Would you say they offer the same performance, manual vs auto tune?  If so then we can say the auto tune is just for convenience?  If you have used both, what would be your advice?

I would love to hear your opinions.

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73

Mike
KD2CJJ
KD0REQ
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Posts: 1050




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« Reply #1 on: May 10, 2013, 02:14:11 PM »

if the antenna is not stable, I'd go after that first.
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KD2CJJ
Member

Posts: 369




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« Reply #2 on: May 10, 2013, 03:35:24 PM »


This is a tuner question, not an antenna question thank you!


if the antenna is not stable, I'd go after that first.
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Mike
KD2CJJ
WB2WIK
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Posts: 20666




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« Reply #3 on: May 10, 2013, 03:40:41 PM »

You may find with a good manual tuner that you really don't have to touch it up much.  The AT may be re-tuning much more often than necessary.

Have you tried a manual tuner (even a borrowed one) just to see what happens?
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KA4NMA
Member

Posts: 357




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« Reply #4 on: May 10, 2013, 07:01:22 PM »

Hi,

I have a LDG Auto Tuner AT 100 PRO II - it has worked very well for me... Unfortunately the bandwidth of my antenna is very narrow (mini beam) and on top of that where I have my antenna depending on the direction its pointing half of the antenna is over my house and the other half is not.  In other words, the tuner is getting a workout and some times not needfully!    Even when i have not changed the frequency a full  auto tune is forced which is almost like doing a manual tune since I am using the RF sensing feature of the tuner (lower wattage to 10 watts, switch to CW, send carrier, wait a few seconds for tune) Is is a major issue?  Definatley NOT!



If the tuner starts tuning without a frequency change, that indicates that the swr has changed on the antenna.  It could be a faulty coax or trouble with the antenna.  My SGC tuner is set to do a retune whenever the SWR raises above 2.  You could also have an issue with tuner.  At what SWR level does the tuner do a retune? Have you tried the tuner with a different antenna?  Also how do you know that the tuner is getting an unnecessary workout? When part of the antenna is over the house, the roof can affect the antenna.

Randy ka4nma
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KD2CJJ
Member

Posts: 369




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« Reply #5 on: May 10, 2013, 09:12:32 PM »

Thanks you get what I am saying...

My mini beam on 20 meters is below 2:1 from 230 to 315.  With a lowest of 1.2:1.  No tuner..

The auto tuner will kick in a tune at 1.7:1 and for the entire 20 meters I get 1.0:1 to about 1.4:1
Once the tuner does a full tune. 

Partial fast  tunes can be as high as 2.0... Then I talk and a full tune kicks in...

What exacerbates the situation is my antenna rotates half over the house..this affects the Swr slightly...the auto tuner doesn't like this because it memorizes the frequency for a previous low full tune then I rotate the beam and it kicks In a fast tune, sees swrs are above 1.7 then a full tune when I talk...

As you can see this gets old fast...

I have never tried a manual tuner thus why I am asking if 1. will i get a better tune or more efficiency and 2. It won't be any more cumbersome then the current situation.


You may find with a good manual tuner that you really don't have to touch it up much.  The AT may be re-tuning much more often than necessary.

Have you tried a manual tuner (even a borrowed one) just to see what happens?
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Mike
KD2CJJ
KE3WD
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Posts: 5689




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« Reply #6 on: May 11, 2013, 06:31:35 AM »

If rotating the antenna truly results in a high SWR change while staying at the same frequency, changing to a manual tuner may get you into trouble, as the manual tuner will be tuned to that first situation, you rotate the antenna and the SWR changes, the manual tuner would not detect that.  You may be able to keep transmitting, but you also may be forcing your PA into Foldback, or worst case scenario of damaging Output Tran$i$tor$. 

**What you really need to be doing is finding out WHY the antenna is changing SWR when rotated.  This may or may not be caused by the proximity to the house, at this point that is only an assumption as far as I can tell.  Is there perhaps a Metal Roof involved? 

**Your problem could very easily be caused by a bad connection somewhere in the antenna system.  That is the first thing I'd investigate. 


73
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KD2CJJ
Member

Posts: 369




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« Reply #7 on: May 11, 2013, 07:01:25 AM »

I suspect it's the aluminum flashing along the ridge detuning the director or my ridge vent which is huge piece of aluminum that is detuning the reflector.

The Swr rise is very consistent to position and its fairly large rise but not much either ;  usually about .5 to 1 Swr.    I have read enough about high q antennas that they are sensitive to their surroundings. I will for now have to live with this issue... The antenna is fine as it is within specs.  Actually it's a great antnenna for what it is...

I see your point with the manual tuner though....  I'm leaning towards staying with the auto tuner.


If rotating the antenna truly results in a high SWR change while staying at the same frequency, changing to a manual tuner may get you into trouble, as the manual tuner will be tuned to that first situation, you rotate the antenna and the SWR changes, the manual tuner would not detect that.  You may be able to keep transmitting, but you also may be forcing your PA into Foldback, or worst case scenario of damaging Output Tran$i$tor$. 

**What you really need to be doing is finding out WHY the antenna is changing SWR when rotated.  This may or may not be caused by the proximity to the house, at this point that is only an assumption as far as I can tell.  Is there perhaps a Metal Roof involved? 

**Your problem could very easily be caused by a bad connection somewhere in the antenna system.  That is the first thing I'd investigate. 


73
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73

Mike
KD2CJJ
WN2C
Member

Posts: 481




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« Reply #8 on: May 11, 2013, 07:58:41 AM »


This is a tuner question, not an antenna question thank you!


if the antenna is not stable, I'd go after that first.

REQ is right... you need to look at the antenna also.  Maybe raising it ten feet might help and keep this issue of changing swr when turning it over the house from happening.  The tuner is just part of the antenna system. 
As far as a tuner when you add an amp, if you can afford it the Palstar AT-auto would definitely would be nice.  Especially if you use computer control of the radio like HRD.

Rick  wn2c
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KD2CJJ
Member

Posts: 369




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« Reply #9 on: May 11, 2013, 01:23:19 PM »

Yea... thats my goal at some point to raise the antenna...   Its about 6 feet above the ridge... probably need to raise it another 5 -10 feet or so to fix it....Im just too lazy at this point...  I think Im going to stick with the auto tuners at this point....   

Regarding Palstar - I have heard too many complaints with their customer service and flaky products (they either just work or just fail), I just cant handle poor customer service and at the price of the Palstar tuners, I will stick with LDG.

Thanks for giving me food for thought though!


This is a tuner question, not an antenna question thank you!


if the antenna is not stable, I'd go after that first.

REQ is right... you need to look at the antenna also.  Maybe raising it ten feet might help and keep this issue of changing swr when turning it over the house from happening.  The tuner is just part of the antenna system. 
As far as a tuner when you add an amp, if you can afford it the Palstar AT-auto would definitely would be nice.  Especially if you use computer control of the radio like HRD.

Rick  wn2c
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73

Mike
KD2CJJ
W5DXP
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Posts: 3639


WWW

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« Reply #10 on: May 13, 2013, 11:20:41 AM »

... do I go for another auto tuner like the LDG 1000 OR do I go for a good manual tuner...

For what it's worth, I had the same problem and solved it in a different way that doesn't require a high-power tuner:

http://www.w5dxp.com/notuner.htm
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NR4C
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Posts: 312




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« Reply #11 on: May 13, 2013, 04:20:51 PM »

I'mn sorry, but I do think you have an "Antenna" problem.  Fix the antenna and you will have an easier "Tuner" solution.

...bill  nr4c
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KD2CJJ
Member

Posts: 369




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« Reply #12 on: May 14, 2013, 06:08:55 AM »

Bill,

Let me explain to you why you are wrong.  I admit I have not given much information about the antenna thus why your ignorance.  I am running a TGM 26, similar to the Cushcraft MA5B.  Both are mini beams with limited bandwidth or also known as a high Q.  The bandwidth for 20 meters for example is only 100 Khz below 3:1 and about 90Khz below 2:1 with a resonance point at 1:1 tuned for where I tuned it.  This meets the advertised specs.  As you may not be aware when you have a high Q antenna the more sensitive the input impedance is to small changes in frequency.  As an example Loop antennas also have a very high Q which can be a few hertz to a few Khz depending on the size of the loop.  Mini beams are shortened beams both the director, reflector and boom length.  This all contributes to having a high Q.  Both antennas, TGM and Cushcraft deploy Capacitance hats to improve the bandwidth by electrically lengthening the directors  and reflectors; though not enough to allow for enough bandwidth to cover all frequencies accros certain bands (for example is below 1.5:1 SWR for the entire 15 meters, 17, meters and 12 meters).

With all that said, for 20 meters I want to be able to operate in the CW and Digital part of the band.... that takes me to at some points 3:1 and even as high as 6:1 at the edge of the lowest part of 20 meters (the highest part of the band is 2:1 which I tuned it to be).  Thus why I NEED a tuner and why the antenna IS NOT BROKEN! 

I do not have an option of a larger antenna, and I made a conscious decision to use antenna as such with knowing the limiting factors (high q and losses outside the resonant range) and necessary equipment to compensate (somewhat ) for those deficiencies.

With with that said, I believe the answers to my question have been answered... From the answers and my own readings it seems to me there is NO benefit to going to a manual tuner, either efficiency or function thus why I will stick with an auto tuner... I do particularly like LDG whereby you can auto tune, then tweak the tuning by adding capacitance or inductance...

I'mn sorry, but I do think you have an "Antenna" problem.  Fix the antenna and you will have an easier "Tuner" solution.

...bill  nr4c
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73

Mike
KD2CJJ
N1UK
Member

Posts: 1589




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« Reply #13 on: May 17, 2013, 04:32:26 PM »

I like to have control of my station and all my tuners are manual. They generally have better power handling capabilities and are cheaper.

I will probably never have an auto tuner, they just don't meet my operating requirements. That said, auto tuners are useful if you are using them in a remote setting such as at the base of a non-resonant vertical.

Mark N1UK
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GW3OQK
Member

Posts: 157




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« Reply #14 on: May 18, 2013, 10:09:04 AM »

With an SWR quote " 3:1 and even as high as 6:1 " the antenna may not be broken, but its not a 50 ohm antenna. Feeding it with ladder line and using a balanced tuner at the shack is likely to be more successful in my view.

Andrew.
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