ATAS Antenna FAQ
Version: 1.0 beta
By: Chris Salinas N0TTW

1: What is this FAQ all about?

This FAQ is to help provide some information and tips on the use and troubleshooting of these antennas. Information gathered for this FAQ comes from many sources. This FAQ is a BETA version until it is revised enough to be somewhat complete (no FAQ is ever complete). Also check back for updates to this FAQ. Input on this FAQ would be appreciated!

If you can add, correct and/or provide additional information for this FAQ or any comments, please email me at [e-mail] . When responding to this FAQ via email, please place in the subject line "FAQ Info".

DISCLAIMER: Use of this information in this FAQ is left to the user and the user will take full responsibility for the outcome. The writer and contributors will not be held responsible for any damage to any equipment from the use of this FAQ.

2: How can I tell what type of antenna I have?

The ATAS series of antennas is a design by YAESU. These antennas are a compact and tunable alternative to the larger and bulkier tunable antennas. Because of their small size, they are not as efficient as the larger antennas. The following antenna descriptions are as follows:

2.1 ATAS-100: This antenna was the first antenna introduced from YAESU. The antenna is identifiable by its bellowed tuning section. Length of the antenna ranges from 1.4 meters (4.6ft) to 1.6m (5.25ft), weighs approximately 930g (2 lbs), maximum power of 120W (SSB) and tunes in the 2/6/10/15/20/40 meter bands as well as the 70cm band with a proper counterpoise. Requires a SO-239 type connector for mounting.

2.2 ATAS-120: This is the second generation antenna introduced. The antenna is identifiable by its "sliding tube" tuning section. Length of the antenna ranges from 1.4 meters (4.6ft) to 1.6m (5.25ft), weighs approximately 900g (2 lbs), maximum power of 120W (SSB) and tunes in the 2/6/10/15/20/40
meter bands as well as the 70cm band with a proper counterpoise. Requires a SO-239 type connector for mounting.

2.21 ATAS-120A: This is an upgraded version of the 120. The most noticeable thing is the rubber boot that slides over top of the whip mount. However there is More water-proofing seals internally.

2.3 ATAS-25: This antenna is the first portable antenna introduced by YAESU. The antenna can be mounted to a standard camera tripod. The tuning is done manually by hand. The base of the antenna has a SO-239 connector at right angle to connect the coax using a PL-259 connector. Length of the antenna ranges from .6 meters (2ft) for transporting and extends to a maximum of 2.2m (7.2ft) during operations. It weighs approximately 930g (2 lbs). It has a maximum power handling of 100W (CW/SSB @ 50% duty cycle) or 50W (AM/FM) in the HF/50Mhz and 50W (All Modes) in the 2m/70cm bands. It can tune at 10/15/20/40 meter bands for HF with a proper counterpoise setup.

3: What kinds of accessories are available for my antenna?

The following items can be used with the ATAS antennas. Use of these accessories will depend on the situation at hand.

3.1 ATBK-100: This is a counterpoise unit for use in the 6/2/70cm bands. It is usually used for limited setups like a balcony railing. Comes with 4 radials, 2 of which are used for 6 meters. (ATAS-100/120/120A only)

3.2 Diplexer/Triplexer: These are normally used to combine several different bands into one coax to the ATAS. There are many different types and it depends on the radio and what signals you want to go to the antenna. The most common one used is the Comet CF-706A.

3.3 Antenna controller: These are normally used for non-Yaesu and older Yaesu radios. The controller can be homebrewed or commercially bought. MFJ-1925I2 is for the ICOM IC-706 radio specifically and the MFJ-1925 is for all other radios. AM-Com also made a controller as well. There may be other manufactures that make a controller.

3.4 Mounts: Depending on the use, the ATAS-100/120 antenna requires a SO-239 type connector on the mount. Mobile mounts should be "heavy duty" because of the vehicle's movement and speed. DO NOT USE a single magnet type mount! Mobile mounts can be homebrewed or bought commercially. A common mount recommended by Yaesu is the Diamond K400C. Base and portable station setups can use mobile or homebrewed mounts as well.

4: How do I install this antenna correctly?

When installing these series of antennas, there are some basic things that will make the antenna operate better and maybe last longer. Here are a few tips:

4.1) Use the proper mount for the situation.
4.2) Use high quality coax when possible.
4.3) For a vehicle, make sure the mount is well grounded!! To do this:
4.3a) Remove the paint where the mounting screws for the mount will go.
4.3b) Run ground straps to parts that are hinged to the body (trunk, door, etc).
4.3c) Make sure resistance from the mount's ground to the negative battery terminal is less than 3 ohms. Sometime this is not possible, just get it as low as you can. Try putting a ground strap from the body to the frame.
4.3d) Check all standard vehicle grounds (radio, fans, etc) for a good connection.
4.4) For base or portable use, use enough radials for a counterpoise.
4.5) Use an O-Ring or rubber washer to seal the bottom of the ATAS-100/120 on the mount. This will help reduce corrosion on the connectors.
4.6) Wind 6-8 turns of coax into a 6" loop for RG58, 9" for RG8/U and larger. Get this loop as close to the antenna as possible.

5: Can I use the ATAS on the WARC bands?

The ATAS antenna was not guaranteed to work on the WARC bands (17, 12 and 30 meters). This is because of the internal coil and the spacing of the wires. However, the antenna will tune and operate on these bands as long as you use only 50 watts. Based on comments and my own experience, 50 watts is a safe bet.

6: How do I troubleshoot the ATAS-100/120?

The ATAS 100/120 antenna, like all other mechanical devices, can cause some problems. Other problems can be caused by improper installation, moisture and such. The first thing to do is identify the problem and use the problems and possible solutions below. It helps to have the Technical Manual for the type of antenna you use, depending on the problem. The technical manual also helps if you need to order a part from YAESU for the antenna.

6.1: My ATAS-100/120 doesn't move when I try to tune it. What do I do?

Make sure your radio is setup for the ATAS. Check your instruction manual to make sure the radio knows you will use the ATAS antenna.

6.2 My radio is setup for the ATAS in the menu. When I tune it, it doesn't move. What's the problem?

The antenna requires certain voltages to move, 10+ volts to go up and <10 volts to go down. So use the following steps to determine where to start. You will need a volt meter and an adjustable power source of some type to do some of the steps:

6.2a: Remove the antenna from the mount and inspect both connectors.
6.2b: Push the tuning button(s) on the radio or antenna controller, measure both the UP and DOWN voltages on the mount's antenna connector. The center pin is positive.
a: If the radio or your controller is trying to move the antenna up, you should read a voltage of 10 volts or higher. This should not exceed 15 volts.
b: If the radio or your controller is trying to move the antenna DOWN, you should read a voltage of 9 volts or lower. This should not go below 6 volts.
6.2c: Apply 12 volts to move the antenna UP and 8 volts to move the antenna down.

NOTE: Make sure you put the positive lead on the center pin of the antenna! Damage to the antenna will result if you don't do this.

6.3: I checked my voltages, connectors and antenna, but my antenna still doesn't move when I remount it. What do I do next?

There is a possibility that the center pin is not making contact with the center connector on the mount. You can either replace the mount or try using a small spring. Find a small spring that will fit inside the center of the connector on the mount. Cut it to a length that will allow the spring to compress enough for the antenna to mount. You may be able to find this spring in a retractable ballpoint pen. The spring should only go 1/2 the way up inside the connector. This gives the spring some room for compressions.

6.4: The voltage from my mount's connector is too high (or low / or no voltage), what do I check next?

Remove the coax from the radio (or controller) and insert a T connector between the coax and radio (or controller). Press the tuning button(s) and check for the same voltages as you did in step 6.1b above.

6.5 I did the step in 6.3 and it looks good, what should I do now?

If you have any other items connected between the radio (controller) and antenna mount (IE: SWR meter, diplexer, etc), check those items as well. If the voltages are fine, replace the coax and/or mount. If the voltages are still bad at the radio/controller, replace or repair it.

6.6: When I apply 12 volts to the antenna, it won't go up. It will go down with 8 volts. What could be wrong?
OR
When I apply 8 volts to the antenna, it won't go down. It will go up with 12 volts. What could be wrong?

This problem may require disassembly of the antenna. More than likely your antenna's motor control board is bad. You need to repair or replace this board. Make sure you get the right board for the right antenna.

6.7: When I apply 12 volts (or 8 volts), it hums (vibrates, makes noises) but doesn't move, what's the problem?

If the antenna does move or moves slowly, you have several things that could be wrong. Can be anything from the motor control board to something mechanical (bearing, drive rod, etc). The only way to find out is to disassemble the antenna and examine the components.

6.8: When I removed the antenna from the mount, I heard something inside rattled (or rolled around), what could that be?

It might be the ball bearing(s) inside, if it has a rolling around sound. The ATAS-100 has 4 bearing and the ATAS-120 has 6. Either way, you will need to take it apart and find out.

7: How do I disassemble and/or reassemble the ATAS antenna or get technical information?

You can go to the files section at:

http://groups.yahoo.com/group/YaesuATAS/files/

Go to the folder for your specific antenna. If we have the technical manual or instructions, it's there.

8: Where can I get a copy of the installation manual for the ATAS?

You can get a copy of the installation manual from the files section at:

http://groups.yahoo.com/group/YaesuATAS/files/

Go to the folder for your specific antenna.


9: Where can I get information on the motor driver IC for the ATAS?

You can get a copy of the specification sheet from the files section at:

http://groups.yahoo.com/group/YaesuATAS/files/

Go to the folder for your specific antenna and look for the following files for your type of antenna:

ATAS-100 = 3763.pdf
ATAS-120 = 6285.pdf
ATAS-25 = N/A (no motor is used)

10: I have a Kenwood radio and want to control an ATAS-100 (or120); can I make a controller instead of buying one?

Yes you can! There is a schematic and pictures available in the group. It will control both the 100 and 120. Go to http://photos.groups.yahoo.com/group/YaesuATAS first and click the SCHEMATIC folder. There you will find 2 folders.

The DC_Coupler folder has the interface that goes between your radio and antenna. It helps provide the DC voltage up the coax.

The Voltage Controller folder provides a schematic to interface with the DC coupler.

11. I can't read the schematics for the DC coupler (or voltage controller). Do you have a larger version of the schematic?

There is a larger schematic for both items in the FILES section if the originals are too hard to read. You can find them at http://groups.yahoo.com/group/YaesuATAS/files/ and they are listed as DCCONTROL.GIF and DCCOUPLER_ATAS.GIF.

12. You mentioned Diplexers and Triplexers, I have a Yaesu FT-847 that has 4 separate connectors (HF/6/2/70cm). How do I interface all of them?

In this situation, it can vary depending on the DIplexers and TRIplexers that are available. You could use a diplexer for HF and 6 meters with a triplexer that does HF & 6/2m/70cm. The important part is to let the HF get to the antenna. The HF connector on the radio passes the voltages to tune the antenna.

13. I can't transmit on 80 meters (or 160) meters, why can't I?

The antenna is only guaranteed to 40 meters. If the radio is set to use the ATAS antenna, it won't let you transmit on those bands.


THE FOLLOWING ARE POSTING MADE TO THIS GROUP THAT HAVE VALUABLE INFORMATION!

========================
In [e-mail], "Ron Schroeder" wrote:
> Hi,
>
> For anybody that has opened up their antenna, what gauge wire is it
> wound with and what is the length and diameter of the coil?
>
> Thanks
>
> Ron
> WD8CDH

From: "w4cng"
Date: Wed Jun 18, 2003 3:22 pm
Subject: Re: ATAS coil info?

It is about 20 ga, and is like piano wire. BTW, do not think about
unscrewing the brass top piece. The coil wire is spot welded inside
of the bottom of it, and will break if you unscrew it. Been there
and fixed it. Tapped the brass top nut in the side for a 4-40 screw,
unwound two turns of the wire, cross drilled the coil assembly, fed
the wire thru and secured under the screw. The brass top part will
not solder. I now use that ATAS 120 for portable use with 9 feet of
#14 stranded wire and a 3 mag mount. Ground radials are plugged into
the mag mount using bannana plugs and sockets. The radials are all
1/4 wavelength using AC zip cord, one wire tuned to 10, the other
tuned to 15 meters. 3 sets of these gets you 10-40 meters not
including 30 meters (I do not do CW). Tunes 10-40 meters. If you
want to operate 6 meters, trim the wire to 50 inches. Pictures soon
to be posted in Photo's section, along with my 60 inch whip mod of my
other ATAS-120 I run mobile, with a good 25% improvement in radiation
efficiency.
Steve W4CNG

========================

From: Nick Marsh
Date: Mon Apr 5, 2004 9:30 pm
Subject: Roll pins coming out?

Hello to the group,

On my Atas100 I am constantly having to check the roll pins in the base,
they seem to want to dislodge and move outwards. Is there a fix for this?

Thanks,
Nick
WB4SQI

From: [e-mail]
Date: Wed Apr 7, 2004 7:05 am
Subject: Re: Roll Pins Coming out?

For those of you who think this doesn't happen CHECK your ATAS 100 antennas. I have seen it happen on nearly every ATAS I have looked at. It has been something I have put out both here and in the FT 100 Group as well. The main version of ATAS 100 to look at for this problem is the base, the section that actually screws down to the SO 239, that has 2 small Phillips screws at the top and one pin at the bottom. If the bottom pin has worked loose to the point that the antenna is unstable, and you have experienced intermittent tuning, chances are the tab at the base of the matching section has broken away from the coil. No big deal to repair in this version, but in the older ATAS antennas, the ones with only pins and no screws in the base, it is a HUGE pain in the ***.
Take Care, God Bless and 73
DE KG4FET Sandor

======================

From: Dan Sawyer
Date: Sun May 16, 2004 9:20 am
Subject: ATAS 'pin' question

The 'pin' has fallen out of my ATAS. The antenna seems to work properly.
What does the pin do? What are the effects of the missing pin??

Thanks,
Dan

From: [e-mail]
Date: Mon May 17, 2004 11:46 am
Subject: RE: ATAS 'pin' question

Dan,
The pin in the bottom of the "base" section keeps that large "doughnut" of steel at the bottom of the base from turning. It is my recommendation that you replace it ASAP. I have seen several ruined coils, or coils that have come unsoldered at the base because the antenna can turn within that black PVC tube at the bottom. I have managed to get one of the bases that came through here tapped for a small screw and added LOCKTITE to it to stop it from coming unscrewed. You actually can add a little LOCKTITE to the new pin too but if the hole in the PVC is wallowed out the pin will be stressed and come loose again. A screw will help prevent this. Even the slightest bit of movement on that bottom section can cause one or both of the main solder joints on the coil inside to break loose. I am going to assume that you have the base with 2 screws at the top and 1 pin at the bottom correct? If so it is one of the "new" models. Older models had one pin at the top and 1 at the bottom, and although Yaesu says this style cannot be repaired, it can be and NOT BY THEM!

Enough is enough. BTW as you can see I cross posted this to the FT 100 group as well.
Take Care, 73 es All the best
DE KG4FET Sandor
Please feel free to email me on or off the list if anybody needs help.

==========================
From: "jcohen17_1999"
Date: Tue Sep 7, 2004 11:11 pm
Subject: Atas base problem

I have an Atas 100 that i replaced the motor which was quite coroded and a new
circuit board but still fails to function. I believe i have a bad capacitor in the base and need to disassemble. I have a pin at the top and one at the bottom. I would appreciate advice or am willing to pay someone to fix if they have experience in doing so.
thanks

joel

From: "Keith Beckmann"
Date: Wed Sep 8, 2004 9:43 am
Subject: Re: [YaesuATAS] Atas base problem

The pins must be removed, or drilled out entirely. The pin at the base is
holding the outside ferrule (Chrome base) and inside thread section from
unscrewing. If you look up inside the base, you should be able to see some
of the threads visible.

Start at the base pin. Route out a good sized square hole on the bottom
pin, and try to remove it with a vise grips, or dikes. It needs to pull
straight out. I used a dremel tool with a small bit to remove the plastic.
The plastic will need to be replaced with epoxy once you are done, so don't
be afraid to remove as much of the plastic as needed to access the pin. The
plastic around the pin is about 3/16" deep, and you will hit the chrome
ferrule underneath it. Don't be afraid to remove the material all the way
down to the chrome ferrule, as you may only get one shot to grab the pin
correctly. There is an O-ring seal 3/16" or so above the pin, so be careful
when routing the plastic above the pin. Grab the pin with a small vise
grips (buy a new one small enough to grab on to it properly, it will be
worth it) If you can pull the pin out you will save yourself a large
headache. You may need to twist the pin to remove it. Again, you may only
get one or 2 chances, so grab it well the first time.

I was not able to remove my pin, as it just would not budge. I used a small
diamond cut off to cut the bottom pin flush with the metal ferrule. I then
center punch it, and drilled it out. This is not as EZ as it sounds. The
chrome ferrule is brass and the pin is stainless. You will need a drill
press, with a vise and a lot of luck. You could drill the pin, be very
lucky, and get it dead center as I was with the top pin, but probably not.
As you drill, pull out the bit occasionally and look. The pin goes quite a
ways into the center threaded section. Once you hit plastic, you have the
pin removed. More than likely you will drill slightly off-center and miss
the pin. This is OK, but you will probably need to drill a 2nd hole on the
other side of the pin, opposite of where you just drilled to loosen the pin.
You can then bend the pin, or what's left of it and get it out. It's
important not to drill too deep, as you will not be hitting the center of
the PL-259 connection. Once this pin is removed, the chrome ferrule will
unscrew, and you can remove it.

Once the bottom ferrule was removed, cut a slot in the plastic, from the top
pin all the way to the top ferrule, and simply slide off the plastic cover.
This will allow you access to the top pin, and try to remove it. If you
can't get it out, you may just cut it off and leave it alone, as there isn't
much it does for you to remove the top section.

Take a look at the ground connection at the base of the coil once you have
it apart. This ground is what is probably preventing the tuning. The
capacitors will not stop it from tuning, just from getting a good SWR. You
can meter the base, and you should see 28 K Ohms from the center pin to
ground. You should have 0 ohms from the bottom and top ferrule, and 0 ohms
from the center pin at the base to the center pin of the circuit board.

Once you get the antenna working, you will want to fix the plastic cover. I
used a sandable aluminum based epoxy called Hardman Machinable Epoxy:

http://www.labsafety.com/store/product_group.asp?dept_id=9168&parent_id=185

I used a piece of heavy masking tape and covered the outside of one of the
hole with it. I then mixed the epoxy, and filled in the hole. Then I put a
second piece of masking tape inside to form a form for the epoxy to sit in.
Before the epoxy was completely hard, I removed the tape and let it set up
for 24 hours. A little filing, and then sanding made it look perfect again.
I did the same to the other side. Once dry, I painted the plastic cover
with black paint.

You could put the pins back, or even replace them with a threaded screw. I
chose to leave the pins out, as I can now simply unscrew the base to get at
it again. My base chrome ferrule had 2 holes drilled in it, and I didn't
want to leave it with the holes, so I drilled a larger single hole, tapped
it, and threaded in a brass screw. I actually used an SAE tap, and threaded
in a brass metric screw until it jammed. I then cut off the screw, and
filed it flat. A little solder filled in all the gaps.

You can't tell the base was even apart, except that there are now no pins,
and I painted it gloss black.

There is a picture of it in our photo section, called "Repaired ATAS 100
base":

http://photos.groups.yahoo.com/group/YaesuATAS/lst

This is a picture of where the slots were cut in the plastic cover. You
can't see it in the picture, but I can just barely tell where the slots
were, if you know where to look.

Good luck, and don't be afraid to ask.

Keith
KB9WMJ

From: "Keith Beckmann"
Date: Wed Sep 8, 2004 7:43 pm
Subject: Re: [YaesuATAS] Atas base problem

Oh, I almost forgot.

I drilled out the top pin, and replaced it with a screw that is cut flush
with the ferrule. I then cut a slot in it, so it can be removed later. I
really don't see a lot of need in removing the top section, as you can get
at the connection from above by removing the PC Board. If I had to do it
again, I would have left the top pin in place, and cut it flush with the
ferrule.

When you are rebuilding the plastic cover, the inside surface is as
important as the outside surface, since it needs to be water tight.

==========================

From: "wa6mha_glen"
Date: Tue Dec 6, 2005 9:22 am
Subject: My intermittent ATAS100 and ATAS120 Antenna

After several years of use, my ATAS100 antenna developed what seemed
to be an intermittent condition. The symptoms were intermittent
strength on receive, high swr, and many times the antenna would fail
auto tune. If it did tune it would go out as soon as I keyed up a
few times. I had already bonded the mount to the back hatch door of
my 95 Explorer. I also have braid across the hinges. I ran many
tests including a mono band whip. The whip seemed to work fine with
the mount. I thought of a mount or cable failure so I did a
continuity check with an ohm meter. As far as I could tell the mount
and cable were OK. That meant the antenna had failed like others I
had read about. Positive it was now the antenna I purchased the
upgrade, an ATAS120. I installed it on the same mount and it tuned
up great. I thought I had solved the problem. Wrong! As soon as I
drove my Explorer the popping signal, and the auto tune failure
returned! I was now out $300 and still was in trouble.

The answer is this...
The K400C Trunk/Hatchback Mount SO-239 I and so many use, is
actually made is several pieces. The female "pin" that the antenna
male mates to is a female on top, and a threaded male on the bottom.
This pin screws into another piece that the center wire of the coax
solders to. You can see this part if you unscrew the cap on the
bottom of the connector. This assembly is what holds the SO239
connector together. It seems that after many uses the female pin
unscrewed enough to allow the connection to be loose. This in turn
caused all my trouble. It was just loose enough to cause trouble
only when the heavy side load that was put on it. This in turn got
worse when I drove. The lighter fiberglass whip and the ohm meter
did not have the weight to side load the connector enough. I
unsoldered the coax, used a screwdriver in the "slot" and tightened
the pin 3 turns until solid. After that the ATAS100 started working
as always at all speeds and the RX, and TX was solid! After several
weeks of mobile use without any failure of the ATAS100, I put the
ATAS120 on the same mount and it's still working great with my FT-
857D. I paid the price of assuming the ATAS100 had started to fail
because of what I had been reading. I wonder how many more "mount"
failures have been blamed on the antenna? I hope this helps someone
save $300.
Glen
Wa6mha