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Old 12-21-2009, 03:21 PM   #1
TN-Tom
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Question ATAS 120 won't tune ......

I have installed an FT857D with an ATAS Screwdriver 120 in our Winnebago Adventurer 38J. The antenna is mounted on the ladder using PVC pipe and grounded to the coach frame using 10 gauge stranded wire. The radio is grounded to the steering wheel mount under the dash. I can't get the antenna to tune, either, auto-tune or manual. This is true on all bands. I can receive very well, however. When the radio is tuned to 29.600 Mhz the SWR is 5.3. When I'm tuned to 7.200Mhz, the SWR is 17.2. Using my analyzer the antenna will tune to 169.23 Mhz and an SWR at 1.0. Then analyzer continues to give me the same numbers regardless of the frequency I use and press "auto-tune" once the radio is hooked to the antenna again.
Does the whip move up and down or is there a coil that moves internally in the larger black portion of the antenna? I'm at a loss. Any thoughts?
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Old 12-21-2009, 03:51 PM   #2
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Tom,
I think there is a menu setting in the 857 for the tuner. Do you have it set for ATAS?



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Old 12-21-2009, 06:11 PM   #3
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Default ATAS 120 won't tune

Yup! That was one of the first things I did during the radio install.
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Old 12-21-2009, 07:38 PM   #4
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Have you tried some of the Yahoo groups for the FT857 or Atas120? Might be a good place to start FT-857 http://groups.yahoo.com/group/FT-857/
or FT-857D http://groups.yahoo.com/group/FT-857D/
or http://groups.yahoo.com/group/YaesuATAS)
I have the 857D, but not the Atas.



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Old 12-21-2009, 08:47 PM   #5
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Have you tried to run a ground ground wire from the antenna to the radio to make sure it is grounded to a common ground.

Ken
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Old 12-21-2009, 08:57 PM   #6
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Tom, great combination you have chosen for your camper.
A couple good bets for answers would be to Google your antenna and then choose the "E Ham" review and go to it. Read the comments and choose one or a couple hams that are commenting on the antenna and ask them your question. They will probably have the answer.

Another place to go to is K0BG 's site and read it over. You may be able to answer your own question after reading there.
http://www.k0bg.com/ In your reading there you will find his email and he will correspond with you if you are patient.

Did you buy the antenna new or used?

Usually the whip itself does not move. The antenna will tune by a contactor moving up and down in the coil ( the large part at the base).

It would be nice to see pictures of your installation.

Good luck.
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Old 12-21-2009, 09:07 PM   #7
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Tom, you also could call Yaesu Headquarters and talk to an engineer and see if he has some answers for you. It is an easy way to get the information right from the manufacturer. The guys there are easy to talk to and encourage consumer calls.

714.827.7600
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Old 12-21-2009, 09:25 PM   #8
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Thank you, Gentlemen for all your thoughtful replies. I will: 1.) Try the Yahoo groups, Andy; 2.) Try running a ground wire from the antenna to the radio to check for a common ground, TXiceman; 3.) and Jim, I bought everything new, although I may be a bit aged! I did do some research on Eham and found some of the grounding problems early on as trouble and thought I had it covered, I will, however, go to "K0BG.com". Thanks. I'll be back with results. Given the holiday approaching, it may take a few days to get things resolved. While new to this net, I will try to get a pic or two for you. 73, TN-Tom
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Old 12-22-2009, 07:01 AM   #9
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Hey Tom, I can relate to the age thing, just keep at it, you will get it.

The RF ground is very important and only you know what you have relative to your installation. It is often convenient to use a shorter whip over a top hat. Looking at it from the top down, it gets the antenna top higher and the base higher and above the engine (a good thing) too. You don't have much metal (ground plane) in your camper so you have to create it.

Perhaps think about the Tarheel tilt up roof mount, or something similar.

Are you trying to achieve the capability of trans/rec running down the road, or just when you are parked (recommended).

The latter is easier to achieve as far as the antenna goes.
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Old 12-22-2009, 04:12 PM   #10
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Quote:
Originally Posted by TXiceman View Post
Have you tried to run a ground ground wire from the antenna to the radio to make sure it is grounded to a common ground.

Ken

Ken that is the most times that I have seen the word ground used in a sentence that still made sense.

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Old 12-23-2009, 05:19 PM   #11
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Default Atas 120

A GOOD SOLID GROUND is NEEDED when you install an ATAS 120 on ANY Vehicle. I have one on my Blazer and my RV, Run a separate 1" copper braid line from the base that the ATAS 120 is mounted on to the Chasis. make sure you have a good clean contact on the chasis.



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Old 01-05-2010, 02:04 PM   #12
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Red face ATAS 120 won't tune

I called Yaesu and I got the same word about grounding. In addition I was told by them to ground the negative lead of my power supply. This was in addition to grounding my FT 857 to the chassis. I'm using RG 58 coax with one connector in about the middle of the line. I've only been able to get the antenna to tune to about 1.8 SWR on 20 meters. I can hear traffic on the HF bands, but, can't get the transmitter to put out any power to speak of. I have it set to peak transmit power of 100 Watts and I doubt if I'm getting 5-10 out.

I have a disability which limits my mobility and I need help in getting to the back ladder and up to the antenna to check the ground wire up there. The ground goes from the antenna base down to the frame of the coach. I hope I can attach pictures of one guy who was helping me take a coil of coax down which I thought would act as an RF chock. It fully upset the tuning when wound up. I'm still working on tuning. I, also, have enough RG 8 to re-wire the antenna when I get it down. That may help in loss. There is no doubt that getting this ATAS 120 to play is tricky.
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Old 01-06-2010, 11:42 AM   #13
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I have not had any problems with my ATAS120. Before I purchased it I read about the problems on line and it appeared that the biggest problem is grounding. If it is well grounded it should not be any problem.

Ken
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Old 01-06-2010, 05:51 PM   #14
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Quote:
Originally Posted by TN-Tom View Post
I called Yaesu and I got the same word about grounding. In addition I was told by them to ground the negative lead of my power supply. This was in addition to grounding my FT 857 to the chassis. I'm using RG 58 coax with one connector in about the middle of the line. I've only been able to get the antenna to tune to about 1.8 SWR on 20 meters. I can hear traffic on the HF bands, but, can't get the transmitter to put out any power to speak of. I have it set to peak transmit power of 100 Watts and I doubt if I'm getting 5-10 out.

I have a disability which limits my mobility and I need help in getting to the back ladder and up to the antenna to check the ground wire up there. The ground goes from the antenna base down to the frame of the coach. I hope I can attach pictures of one guy who was helping me take a coil of coax down which I thought would act as an RF chock. It fully upset the tuning when wound up. I'm still working on tuning. I, also, have enough RG 8 to re-wire the antenna when I get it down. That may help in loss. There is no doubt that getting this ATAS 120 to play is tricky.
Do Not use a RF Choke!!, If you can switch out the RG58 for the RG8.Keep the RG8 length minimal. If you can take some pictures of your installation so i can look at it, i may beable to see something and suggest something to help.

Bob
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Old 01-07-2010, 01:39 PM   #15
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Unhappy ATAS 120 won't tune

Update - I pulled the antenna down. I checked all the ground wires. I kept the antenna on a short piece of PVC and it still wouldn't tune. The best I could get was 4.2 SWR by manually tuning. I called Yaesu. They said that I should get rid of the PVC - period!!! He (Ron) said to use metal pipe and attach the antenna to the ladder. Then, ground the ladder to the chassis. Ron said that the antenna is looking for a ground PLANE and can't see it because of the PVC. I know that there is a small piece of metal plate that is the backer to the ladder on the roof and behind all the ladder connections. Having an RV and getting this antenna to play is a different bag of worms than a car/van/suv. More as it happens.
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Old 01-10-2010, 02:00 PM   #16
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Default ATAS 120 won't tune

Final Solution: I'm attaching 3 pics of the antenna. It works just fine, now. There's NO PVC involved and I used two hose clamps to attach the antenna mount to the ladder. The Yaesu tech - Ron - was right on the mark. From Port Charlotte area of FL, I've had QSO's to Chicago, Corpus Christi, VA, No. Kentucky. I haven't had the time to devote to DX work, yet. I'm happy with what I have and proper grounding was the answer all along.
Attached Images
File Type: jpg Antenna on RV.jpg (34.9 KB, 37 views)
File Type: jpg ATAS mounted.jpg (26.2 KB, 36 views)
File Type: jpg ATAS ladder grounding.jpg (41.0 KB, 36 views)
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Old 01-10-2010, 05:22 PM   #17
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Nice set up Tom, but your antenna is horizontally polarized. And why are you using two ground wires?



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Old 01-10-2010, 07:17 PM   #18
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Looks real nice Tom, and don't forget to take it down when you travel or you might hit some things along the roadside.


JIM
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Old 01-11-2010, 01:49 PM   #19
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I wondered if someone would catch that. It's an optical illusion and a reflection off the shiny back side of the coach. There really is only one ground wire going to the chassis. Don't forget, I have, also, grounded the radio and the negative side of the power supply to the chassis. I hope that answers your question. 73, Tom, N1NDM
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Old 01-17-2010, 03:12 PM   #20
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Tom, I do believe your problem lies in the way you have mounted your ATAS120. Like all vertical antennas, the ATAS requires a very good ground plane to work against. The physical antenna is only one half of the actual antenna, the other half is the image created by the ground currents flowing the ground it works against. A large metal surface is best, but a length of metal pipe is also good. If it is mounted on the end of a PVC pipe and only connected to the MH chasis/ladder via a small wire that will not suffice as an RF ground. The wire has too much inductance. The wire may provide the DC necessary DC ground but the RF ground will be lacking. I have my ATAS120 also mounted to the MH ladder at the top. But I used a heavy metal clamp type mount right to the ladder and then grounded the lower end of the ladder to the MH frame using heavy 1 inch wide braid. It works fine with my FT100D. Mike NA9Q
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