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Author Topic: IC-208H not transmitting  (Read 3216 times)
KF4HOQ
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Posts: 47




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« on: July 16, 2012, 10:24:27 PM »

A couple of weeks ago, a friend of mine and I were talking on 2 meter simplex, then had to switch to a repeater because we were headed in different directions and got out of range of each other.  Right about the end of our conversation, apparently my radio stopped transmitting.  The red LED on the HM-133 lights up, and the radio displays the input frequency of the repeater when keyed down, but it doesn't actually transmit anything.  I've tried multiple repeaters and all three power levels with no results.  Any ideas?

Thanks!
Michael
KF4HOQ
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K2OWK
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Posts: 1066




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« Reply #1 on: July 16, 2012, 10:53:19 PM »

Check your antenna. Sounds like it got disconnected. The transmitter will show a transmitt indication, but will shut down the transmitt power because of a high VSWR. I am assuming you were mobile by your post.

73s

K2OWK
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KA4POL
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Posts: 2029




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« Reply #2 on: July 17, 2012, 12:02:02 AM »

What antenna are you using? How is 70cm? Connect a dummy load to the antenna terminal and check transmit operation.
 The 208 has an SWR detection circuit which will reduce output power during high SWR.
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K9YLI
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« Reply #3 on: July 17, 2012, 05:43:07 AM »

You didnt say if you re-tried  simplex..

maybe  in changing freq  you turned off the  tone  function..
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KB3HG
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Posts: 404




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« Reply #4 on: July 18, 2012, 05:20:25 AM »

After checking the things others listed, if still nothing check the mic cable. Another simplex QSO attempt lets you know if there is RF and audio, try this at the lowest power until you check the antenna SWR.

Tom Kb3hg
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KF4HOQ
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Posts: 47




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« Reply #5 on: July 18, 2012, 11:22:11 AM »

Sorry.....antenna is a Diamond SG7900. I've had it since 2008.  After reading some of the reviews on here about that antenna, it sounds like I need to check the coils for water.  The repeater that we tried, and me testing with other repeaters, were programmed in the memory, so there shouldn't have been any changes in the PL tones, but I'll look at that, too. 

Thanks for the ideas!
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WB6BYU
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Posts: 13341




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« Reply #6 on: July 18, 2012, 03:18:07 PM »

A common failure mode for many VHF FM radios is the final amplifier module going bad.
I've had this happen in three of my radios, including a IC-207.  When that happens
you get maybe a few tens of milliwatts out - enough that you can hear it locally, but
not enough to work stations very far away.  (In one case I could work a repeater
5 miles away when I was line of sight.)

The first check is to see that it is transmitting on the right frequency.  A quick check
with an HT or another mobile station up to 100 yards away should confirm this.  Have
them listen on the repeater input frequency to see if they can hear you.  If they can
hear you when close but the signal fades out less than a mile away, this is a likely
cause.

If you have a power meter, measure the output power of the radio.  In the IC-207 there
are separate output modules for each band, so I would expect that the 440 side still
works.


Perhaps I should clarify my initial statement:  it isn't that this happens often, as most
rigs are actually quite reliable.  But of all the various failures I've encountered it is one
of the most common.  Happens most often when you operate the radio for an extended
period at high power (as might be the case running simplex in difficult conditions),
especially with poor ventilation to the radio.  In one case I was running the radio on high
power and discovered that the car heater was blowing on it.  This may be a side effect
of the cooling fan failing or getting clogged with dust.  Heat build-up is the biggest enemy,
more so than high SWR (though that will contribute to the heat dissipation.)

If that is the problem (confirmed by a check of output power) then the simple fix is to
replace the output module.  Simple, but not necessarily cheap.  I did manage to repair
the module in my IC-28, and it still works, but that isn't for the faint of heart.
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KE5PPH
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Posts: 73




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« Reply #7 on: July 18, 2012, 05:57:49 PM »

Will Bet $5 on bad mic.   Been there , done that.
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KA4POL
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Posts: 2029




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« Reply #8 on: July 18, 2012, 10:11:18 PM »

The failure description is still not quite clear. How do you determine the radio 'doesn't actually transmit anything'? Can you open the repeater, i.e. RF arrives at the repeater, or does the repeater not react on you trying to open it? If you see a reaction of the repeater then this could be a case of no modulation.
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NO2A
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Posts: 801




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« Reply #9 on: July 20, 2012, 01:00:03 PM »

The HM-133 mic on that rig sometimes has a problem with the ptt switch. I`ve had to take mine apart and spray some contact cleaner on the switch a couple times to restore proper transmit/receive operation,but it does work if you do that.
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KA4POL
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Posts: 2029




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« Reply #10 on: July 20, 2012, 09:31:28 PM »

How would the TX LED come on without the PTT working?
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KF4HOQ
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Posts: 47




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« Reply #11 on: July 28, 2012, 03:07:38 PM »

Ok.....I got together with a ham friend of mine today, and we determined that it does transmit on 144MHz on simplex, with his car right behind mine.  He was able to hear my voice clearly.  It still will not hit any of the local repeaters, though.  It will, however, hit the local 440MHz repeaters with no problem.  He seems to think that the top loading coil on the antenna has gone bad.  Does that sound right?
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KE3WD
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Posts: 5689




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« Reply #12 on: July 28, 2012, 03:21:12 PM »

Do all of these repeaters require a PL tone? 

Can you find an "open" (no tone required) repeater to test on? 

Might be the antenna, but might be nonfunctioning Tone as well.


73
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WB6BYU
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Posts: 13341




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« Reply #13 on: July 28, 2012, 04:51:53 PM »

How far away can he hear you on simplex?  Can you put a power meter in line with the
radio and see what your actual output level is on each band (but particularly on 2m)?
Even a CB SWR meter could give you a comparative indication:  put it in his antenna
lead, set his radio to 5 watts output and adjust the control for full scale on FWD.  Then
put the same meter in your radio lead without moving the knob, with your radio set to
5 watts.  If it doesn't come close to full scale, you're not putting out enough power.

I haven't opened up my IC-208 to check, but the IC-207 had separate output modules
for 2m and 440.  When the 2m module died, my radio still worked fine on 440.
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KF4HOQ
Member

Posts: 47




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« Reply #14 on: July 28, 2012, 08:10:57 PM »

3WD, luckily, most of the repeaters around here are open.  I did check for PL Squelch, though.

BYU, roughly 15 feet.  I'll have to see about putting a wattmeter on it.  Good idea, though!
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