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Author Topic: Did I possibly damage my antenna tuner?  (Read 3638 times)
KB2NWQ
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Posts: 17




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« on: November 21, 2011, 02:32:57 PM »

Hi everyone,

I did it again.  We had some storms the other day and I decided to disconnect my antenna from my HF radio.  Of course, yesterday I turned on the radio and tried to auto tune and it took longer than normal.  I couldn't figure out why it couldn't tune until it hit me that I had disconnected my antenna.  After connecting the antenna back on, it tuned 10 meters with no problems, but it appears that it won't tune 15 meters like it use too (not that I can use it).  It use to tune down to below 1.5.  Now it won't tune better than 2.0.  I know it's not a good thing to not have an antenna connected, but should I be worried? It's a MFJ-929 tuner.  The last time I did this, I fried the internal radio tuner.  Most of the tuning capacitors disintegrated. 

P.S., from now on I will placard the radio power switch when I disconnect the antenna.  Live and learn.

Thanks,

GP
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VE3FMC
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« Reply #1 on: November 21, 2011, 03:02:41 PM »

Try resetting the tuner to wipe out the memories and then see how it works after doing that.
Might work, might not. Hopefully it solves the problem.
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WB2WIK
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« Reply #2 on: November 21, 2011, 03:06:36 PM »

I don't ever disconnect my antennas.

The way I'd remember, though, is to always LISTEN to the band prior to transmitting.  If you tune across the band and don't hear any signals, or anything, the antenna's disconnected.  Pretty easy rule to follow. Wink

Hope you didn't fry tuner components.
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AC5UP
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Posts: 3825




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« Reply #3 on: November 21, 2011, 03:29:28 PM »

As mentioned previously, reset the tuner. If you have a dummy load try tuning it on all bands after the reset as a performance check.

Should hit a perfect 1:1 on the first try. If not, you have a problem...................

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Never change a password on a Friday                
KA4POL
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Posts: 1914




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« Reply #4 on: November 21, 2011, 09:54:35 PM »

Forgetting is a pretty usual human virtue. For future cases I'd recommend putting a sticker to the radio upon disconnecting the antenna. And don't forget to do it  Grin
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TANAKASAN
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Posts: 933




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« Reply #5 on: November 22, 2011, 02:49:08 AM »

As someone else suggested on another forum, when you disconnect the antenna pull out the microphone connection at the same time. Once this becomes a habit we*** won't make the same mistake again.

Tanakasan

*** Yes, I have also transmitted into an empty antenna socket, fortunately the rig survived.
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KB2NWQ
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Posts: 17




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« Reply #6 on: November 22, 2011, 01:57:43 PM »

Try resetting the tuner to wipe out the memories and then see how it works after doing that.
Might work, might not. Hopefully it solves the problem.

Hi,

The tuner had a hard time with 40 and 15 meters before the total reset. After the total reset, it tuned 40 meters down to 1.0 SWR, but it still had a hard time with 15 meters.  I then connected a dummy load and it was able to tune every band down to 1.0 instantly.  I reconnected the antenna and it still couldn't tune 15 meters below 2.1 SWR (which I guess is not too bad, but it tuned it down to 1.0 before).

I decided to read the manual and tried manually adjusting capacitance and inductance.  I was able to reduce to 1.0 and all of a sudden the tuner could auto tune 15 meters to 1.0 SWR.  Success, but I'll keep an eye on the tuner and will placard the radio when I disconnect the antenna. 

Thanks for the help everyone, 73's,

GP
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KB2NWQ
Member

Posts: 17




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« Reply #7 on: November 22, 2011, 01:59:36 PM »

As someone else suggested on another forum, when you disconnect the antenna pull out the microphone connection at the same time. Once this becomes a habit we*** won't make the same mistake again.

Tanakasan

*** Yes, I have also transmitted into an empty antenna socket, fortunately the rig survived.

Great idea on unplugging the mic, I'll keep that in mind.
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W5DQ
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« Reply #8 on: November 22, 2011, 02:15:54 PM »

Try resetting the tuner to wipe out the memories and then see how it works after doing that.
Might work, might not. Hopefully it solves the problem.

Hi,

The tuner had a hard time with 40 and 15 meters before the total reset. After the total reset, it tuned 40 meters down to 1.0 SWR, but it still had a hard time with 15 meters.  I then connected a dummy load and it was able to tune every band down to 1.0 instantly.  I reconnected the antenna and it still couldn't tune 15 meters below 2.1 SWR (which I guess is not too bad, but it tuned it down to 1.0 before).

I decided to read the manual and tried manually adjusting capacitance and inductance.  I was able to reduce to 1.0 and all of a sudden the tuner could auto tune 15 meters to 1.0 SWR.  Success, but I'll keep an eye on the tuner and will placard the radio when I disconnect the antenna. 

Thanks for the help everyone, 73's,

GP

If you had T-storms, did the 15M antenna take a strike? Is it a monoband antenna for 15M only or multiband? It sounds like a multiband antenna. If so, are there any tuned circuits on the antenna (like a CC R7/R8 or such)?  Have you checked you antennas to see if they are in place and not damaged.

I once had a dipole that one end broke loose and was on the ground. It worked but the SWR was up. Could figure out why until I found half of it where it wasn't suppose to be  Shocked

I always check my antennas after an electrical storm or when we have really high winds here in the Mojave Desert. Occasionally things come down and have to be fixed. Not too much lately but has happened. At least we don't get ice and snow here  Grin

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
AK7V
Member

Posts: 249




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« Reply #9 on: November 22, 2011, 02:39:29 PM »

Your antenna might have changed.  Mine does when it gets snow/ice/water on it.  Right now, it's about 5 feet lower than it was last week thanks to some wet snow weighing down the trees that support it.
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N4OI
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Posts: 200




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« Reply #10 on: November 22, 2011, 03:38:37 PM »

As someone else suggested on another forum, when you disconnect the antenna pull out the microphone connection at the same time. Once this becomes a habit we*** won't make the same mistake again.

Tanakasan


My microphone is stuck in a drawer around here somewhere... di dit!

73 de Ken  Roll Eyes
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KD6KWZ
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Posts: 276




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« Reply #11 on: November 23, 2011, 08:10:07 PM »

Quote
I decided to read the manual and tried manually adjusting capacitance and inductance.  I was able to reduce to 1.0 and all of a sudden the tuner could auto tune 15 meters to 1.0 SWR.

That makes me wonder that if a servo motor inside got stuck, if this uses one.

On semiconductor manufacturing equipment, they use RF in some processes, often at 13.56 MHz. They have match boxes on these. Sometimes, shaft couplers or belts between the variable cap, or the inductor, & the tuning servo motor gets loose, and you start getting reflected power error. Many of them have a pot hooked up mechanically to feed back the relative position of the cap/inductor being tuned.
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VE3FMC
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« Reply #12 on: November 26, 2011, 04:35:28 AM »

I should have added this in my other post. If you have done some damage to the tuner then you could send it back to LDG.
I had an older AT-1000 that just quit tuning one day. Sent it to LDG and they repaired it for the cost of $25 for parts/labor. Plus the return shipping. So it was under $50 to get it repaired and shipped back to Canada. Plus my shipping costs to them.
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AA4HA
Member

Posts: 1378




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« Reply #13 on: November 28, 2011, 09:58:05 AM »

As someone else suggested on another forum, when you disconnect the antenna pull out the microphone connection at the same time. Once this becomes a habit we*** won't make the same mistake again.

Tanakasan

My microphone is stuck in a drawer around here somewhere... di dit!
Had a problem with a cat who liked to sprawl out on my console and was putting random, very long diiiiii on the air. Rushed home while listening to this entire escapade on 10 meters. Now I unplug the key as well.

At one time it was not a problem; touching any metallic part of the key was about the same as putting your finger on B+. Curious kitty jumped completely over the console and knocked things off of the bookshelf after putting her nose on that. I did not see it happen and can only imagine it was similar to the high speed photographs of a steering wheel airbag deploying. Kitty might have even traveled backwards in time, violating Einstein's rules.

I wonder how many non-amateur conversations make it on the air by VOX.
« Last Edit: November 28, 2011, 10:00:50 AM by AA4HA » Logged

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
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