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Author Topic: ATAS 120 no longer tunes.  (Read 535 times)
KE7DJQ
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« on: November 10, 2017, 08:27:34 PM »

My antenna, paired with the 857D has been working fine for months. In September I removed it and put a cap on the connector to protect it from moisture. I've done this before.

The mount is 1/4 inch stainless steel bent at 90 degrees and screwed to the bed over the back left stake bed pocket. I put a Comet 35DM in the 5/8 inch hole. The radio is on a steel mount over the hump in my truck and grounded to one of the four screws securing it to the floor.   Power comes direct from the battery.

Today I installed a Lido seat bolt mount and head separation cable. I replaced the antenna and now the antenna won't tune. It also won't tune when I put the head back on the body. when it was mounted on my car before that vehicle died.

I went through the INIT step several times with no success.  Not sure what to do next. Nothing seems to have changed. All the connections seem secure. I can hear great on 40m since that's what it was last tuned to.
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K5LXP
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« Reply #1 on: November 11, 2017, 10:28:41 AM »

Does the antenna go up and down with 8/12 VDC applied directly?  That will narrow down where to look next.

Mark K5LXP
Albuquerque, NM
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WA3SKN
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« Reply #2 on: November 11, 2017, 02:12:24 PM »

Well, something has changed.
I would be looking for shorts, opens, and poor connections in general.
Does the FT857 load properly when connected to a known good dummy load?

-Mike.
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KE7DJQ
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« Reply #3 on: November 11, 2017, 07:42:14 PM »

Does the antenna go up and down with 8/12 VDC applied directly?  That will narrow down where to look next.

Mark K5LXP
Albuquerque, NM

It did not go up when I applied 12 volts using my fish finder battery. It is already up all the way, I think.  I don't have anything that produces 8 volts.
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KE7DJQ
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« Reply #4 on: November 11, 2017, 07:45:59 PM »

Well, something has changed.
I would be looking for shorts, opens, and poor connections in general.
Does the FT857 load properly when connected to a known good dummy load?

-Mike.

When I get my multimeter back I can check for those.  By loading properly, do you mean does it operate as an HF radio? Yes, it works fine in my shack when connected to my regular antenna.

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K5LXP
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« Reply #5 on: November 12, 2017, 11:31:55 AM »

I don't have anything that produces 8 volts.

8V is what the radio uses, but it will run on less.  The one I tested would still turn down to 4.8V.  So if you don't have an adjustable supply, 6V worth of batteries (say, AA) would work.

Mark K5LXP
Albuquerque, NM
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K3LI
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« Reply #6 on: November 15, 2017, 06:27:33 PM »

I run 2 of these.  Sometimes they stop tuning.  It is always the same thing.   

1. Take the antenna off the mount.  Clean the antenna mount really well. 
2. Clean out the antenna connector really well.
3. Clean the surface of you mounting bracket. (where the bottom of the ASAT touches it)
4. Screw on the antenna (use some type of sealer inside the connector)
5. Do a factory reset on the radio and re initialize the antenna. (note the 120 is famous for not tuning on vhf/uhf)

It should work again.  If not, some taking the outer sleeve off and clean the coils.

Al this assumes it does not have a short.  But I seem to have to do this once or twice a year.
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