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Author Topic: audio poping in and out...using workman magnet.....  (Read 5951 times)
K3NRX
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« on: June 03, 2014, 06:43:21 PM »

Rig is an FT1802 Yaesu....every repeater I hit, the audio breaks up....this is beyond the typical mobile flutter.....I just picked up a workman magnet for the two meter mobile antenna because the old one was shot and corroded.....I paid $25.00 for this thing....I really hope this isn't the cause of my issue.....I tried tuner cleaner on the magnet contact with the antenna...I tried tightening up the antenna to the magnet....I tried replacing the original PL 259  end connector on the magnet's coax with a new one, soldered up all tight.....I sprayed tuner clear on the radio speaker...all of this, and still I get this audio break up....can someone offer some suggestions as to what this problem is?....again, this is NOT typical mobile flutter....I fear that something is wrong with this magnet, which is NOT good....for the record, this problem happened with my previous magnet as well (the corroded one)......Please advise on what may be causing this....

V
K3NRX

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K5LXP
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« Reply #1 on: June 04, 2014, 06:52:49 AM »

Several things could cause this problem.  First thing I would do is borrow or build a different antenna and give that a try.  That will tell you right away if it's a radio or antenna problem.


Mark K5LXP
Albuquerque, NM
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KB4QAA
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« Reply #2 on: June 04, 2014, 12:53:37 PM »

I'm not sure what you think the magnet has to do with the transmission quality......

Why would you spray tuner cleaner on a speaker?

All it does is hold the antenna frame to the body.  The frame is capacitively coupled to the body.  Even significant movement, rubbing or bouncing is not going to dramatically affect the signal.

The most likely problem is an intermittent mechanical/electrical connection.

Buy or borrow a known good antenna and coax and test with that.
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AA4PB
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« Reply #3 on: June 04, 2014, 01:57:21 PM »

You probably need a new speaker now that you have sprayed tuner cleaner on it.

Have you tried moving the antenna or coax while listening in order to see if you have an intermittent connection? Does the coax shield have a solid connection to the magnet? The magnet provides capacitive coupling to the vehicle but it doesn't work if the coax is not connected to the magnet. Have you checked the SWR while moving to see if it is bouncing around?


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K3NRX
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« Reply #4 on: June 04, 2014, 04:04:23 PM »

You probably need a new speaker now that you have sprayed tuner cleaner on it.

Have you tried moving the antenna or coax while listening in order to see if you have an intermittent connection? Does the coax shield have a solid connection to the magnet? The magnet provides capacitive coupling to the vehicle but it doesn't work if the coax is not connected to the magnet. Have you checked the SWR while moving to see if it is bouncing around?




It appears this problem has cleared up (knock wood)....not sure how, but the audio is clean, with typical mobile flutter for more distant signals...and the speaker still works fine...and it seemed this problem occurred both while moving and while being still.....I am under the impression that these magnets are very cheaply made, as I am not real impressed with the silver braid and conductor in it's coax.....

V
K3NRX
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WB2WIK
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« Reply #5 on: June 05, 2014, 01:58:25 PM »

"Workman" is pretty cheap (mostly CB) stuff.  I wouldn't pay anything for any of it.

I took one of their mag mount bases apart a year or two ago to find they were literally using the magnet itself as the electrical contact from coax outer conductor to the outside world, then a think piece of plastic between the magnet itself and the bottom of the mount where it contacts the vehicle.  Then, I checked the electrical continuity of the magnet: Zero.  There wasn't any, at all.

I have no clue how they thought that would ever work. Wink

I use Larsen NMO mag mounts, which use a piece of thin aluminum as the contact between the coax and the vehicle, so there's a large capacitively coupled mating surface, and full electrical continuity between the coax outer conductor and that aluminum.  They work fine, and cost about the same.
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K3NRX
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« Reply #6 on: June 18, 2014, 09:19:14 AM »

Patched up the antenna which had a gash in it...sealed it with some Goop and covered it heavily/tightly with elecrical tape.....and I am still having the same problem.....Conclusion: it's not the magnets, it's not the antenna, it's not the coax or connections....there is something wrong with this receiver.....Looks like years of being out in the brutal cold has finally taken it's toll....Guess I am gonna have to crack it open and check for loose connecitons and cold solder joints......this is frustrating....

V
K3NRX

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N6AJR
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« Reply #7 on: July 07, 2014, 11:10:04 AM »

goop and electrical tape should make it worse. it would act like an insulator and cut down on the capacitive coupling.  try to ground the shield side of the antenna to ground on the car. give the electricity a return path at RF levels.
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KB2VUQ
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« Reply #8 on: July 07, 2014, 05:17:06 PM »

I hope you painted the goop, magnet and antenna to
match the color of the car. The important thing is to NOT
drill a hole and devalue the vehicle.

Are you the guy from Hamsexy?

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