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Author Topic: IC281H stuck in transmit  (Read 620 times)
WD8KGK
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Posts: 3




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« on: August 15, 2007, 03:32:56 PM »

Was gifted an Icom IC281H.  As soon as I plug the mic in the radio goes into TX mode.  

Any ideas?

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W3LK
Member

Posts: 5639




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« Reply #1 on: August 15, 2007, 04:42:52 PM »

Bad PTT switch in the mic.

An Advanced Class ham can't figure this out?

73,

Lon - W3LK
Naugatuck, Connecticut
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
K0BG
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Posts: 9868


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« Reply #2 on: August 15, 2007, 06:27:39 PM »

There are so many possible scenarios for this problem, with the limited information you have given, it's impossible to pinpoint.

This begs the question, what have you tried? Did you remove the mic (as Lon sort of ask)? Were you transmitting into a dummy load? Etc.?

Alan, KØBG
www.k0bg.com
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WD8KGK
Member

Posts: 3




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« Reply #3 on: August 15, 2007, 07:39:17 PM »

Ooh, you guys are hard on a fella, ain't ya?

With the mic unplugged radio seems to be okay. It receives.  As soon as as the mic plug is inserted the TX indicator comes on.  Yes, bad PTT is the obvious answer.

I was hoping someone would chime in with a "Oh that happened to me and all you have to do is refrangle the franzimater and woggle the whozits."  After all this thing is mostly a microcomputer with a little bit of radio attached.  

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WD8KGK
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Posts: 3




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« Reply #4 on: August 15, 2007, 08:06:37 PM »

I've done further investigation.

I opened the mic, disconnected the micro switch under the PTT button from the PC board, inserted the mic plug into the radio, it goes into TX mode.  So the micro switch is not at fault.

I disconnected the mic cable from the PC board in the mic, inserted the plug into the radio, it does NOT go into TX mode.  So the mic cable is not at fault.

What else on the PC board in the mic is in the PTT circuit?  
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KE3WD
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Posts: 5689




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« Reply #5 on: August 15, 2007, 09:05:19 PM »

>>After all this thing is mostly a microcomputer with a little bit of radio attached.<<

Um, right.

Do you have an ohmmeter and do you know how to use it?

After all, the PTT circuit is mostly a single pole switch with a little bit of cord attached...

!
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KE3WD
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Posts: 5689




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« Reply #6 on: August 15, 2007, 09:08:02 PM »

>>What else on the PC board in the mic is in the PTT circuit? >>

Traces on the PCB, solder connections, possibly a capacitor across the switch contacts...

Back of board may be being shorted by something, take a look, after all, it is only a microcomputer with a little bit of radio attached, right?


.
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K1CJS
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Posts: 6034




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« Reply #7 on: August 16, 2007, 05:01:20 AM »

Greg,

Without trying to sound like a smartass or call you down, have you tried tracing the connections on the board itself?  I know it isn't easy to do, but that is probably the only way to find the problem--unless you buy another mike.  The problem should be simple to find--if you've got magnifying eyes, that is!  ;-)
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KE3WD
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Posts: 5689




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« Reply #8 on: August 16, 2007, 01:34:16 PM »

Hey, if you are condescending first, there ya go...


Maybe I spent too much time behind the repair counter desk and on the phone, but that kind of talk is uncalled for and actually a bit over the top.  

Had too many hams and consumers talk down to me and my techs like that when they obviously didn't know diddly themselves about how to do the job.  

If you want someone to HELP you, think about what you are saying to them, please.  

Amateur Radio is supposed to be about communicating.  


KE3WD said that.

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VK2DYI
Member

Posts: 12




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« Reply #9 on: August 25, 2007, 09:45:55 PM »

Watching with interest.  I dont have my testing gear with me (in the middle of a house move) and have a similar problem with my IC229H.  

It was working fine, driving down the road and then noticed it had stopped scanning and it was in transmit.  Boy was the heatsink hot.

Will have my test gear soon so will start to look.

Andy
ES2DY & VK2DYI
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