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Author Topic: Yaseu FT-8100 - No audio on UHF side  (Read 4879 times)
K4NYA
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Posts: 43




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« on: July 06, 2013, 09:00:23 AM »

I recently reprogrammed my Yaseu FT-8100.  I'd bought it used from a local ham a few months back and it was working fine, although a lot of the repeaters he had programmed into it were either off the air or hard to reach at my QTH.  I reset the radio back to factory defaults and programmed in the repeaters I could hit.  It worked fine while on the bench in my house, but when I put it back in the car, I couldn't get any audio out of the UHF side.  If I key it up, it shows a signal being sent as well as a reply from the repeater, but I get no sound.  When left idle, the meter shows "busy" with one bar most of the time and the green light for that side blinks constantly.  I've adjusted the squelch setting, but it didn't change anything.  The VHF side is working fine. Any ideas what could be wrong here (other than the FT-8100 being a piece of junk)?
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K1CJS
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« Reply #1 on: July 08, 2013, 04:44:47 AM »

I don't own that particular radio, but a lot of dual band radios have two circuit boards that have solid plug and socket conbinations to join them together instead of ribbon cables.  Have you tried pulling the radio and trying it?  My guess is that something was done that knocked the boards apart, either from handling or when you tightened the rig onto the bracket.

Understand that's only a guess, I'm just suggesting from what I've seen over the years.  73!
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K4NYA
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« Reply #2 on: July 08, 2013, 07:30:20 AM »

I got a suggesting to check the CTCSS decode from a guy at QRZ.  I'm gonna check that, but if that doesn't clear up the problem I'm gonna take it back inside & open her up.  I'll check the boards out when I do that. 

Thanks!
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K1CJS
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« Reply #3 on: July 08, 2013, 08:15:46 AM »

Definitely check the CTCSS decode, but if the condition is general--that is is evident on all the UHF channels--it may not be the decode, since you have to turn it on for every frequency programmed.  Of course, if you only have one frequency in memory...   Cheesy
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K4NYA
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Posts: 43




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« Reply #4 on: July 08, 2013, 09:27:44 AM »

No, it's across the UHF band.  I doubt that's the problem, but I'm gonna check it out first since that's a simple fix and doesn't require any disassembly.  Wink
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K4NYA
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Posts: 43




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« Reply #5 on: July 09, 2013, 07:20:55 AM »

Well, the plot thickens!!!

It's not the CTCSS decode that's causing the UHF problem. This radio requires an add-on board for that function, which isn't installed and encode can't be enabled without it. But, according to the description in the manual, it's behaving exactly like it should be if CTCSS decode WERE enabled.

Weird!
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K1CJS
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« Reply #6 on: July 09, 2013, 11:43:28 AM »

Then I would look for a disconnected jumper cable/plug or some sort of missing jumper contact strip that would be removed when/if the decode board was installed.

If there is none, then the decode board would be electronically detected, and the rig may have to be benched to be checked and repaired.
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K2OWK
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Posts: 1055




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« Reply #7 on: July 09, 2013, 11:50:21 PM »

I don't know about the FT-8100, but I have an older FT-4700. It has a balance control for VHF/UHF. In the center both bands can be monitored simultaneously, but if it is turned to VHF side then the UHF will not have any audio. I know it sounds simple, but check if you have a balance control and make sure it is centered if you want to monitor both bands.

73s

K2OWK
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W9IQ
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Posts: 102




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« Reply #8 on: July 10, 2013, 03:13:30 PM »

The FT-8100R has a separate volume control for the sub-channel located on the right side. Have you checked that to make sure it is adjusted properly?

There are two speaker jacks in the back. If something is plugged into the UHF SP jack, the built in speaker will no longer play the UHF audio (same if the jack is dirty or defective).

- Glenn W9IQ
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K4NYA
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« Reply #9 on: July 11, 2013, 09:41:39 AM »

Yeah, the volume and squelch settings are properly adjusted.  Doesn't matter where they are, in fact.  Still don't get anything from the UHF side. Don't have anything plugged into either of the speaker jacks.
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K4NYA
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« Reply #10 on: July 11, 2013, 10:58:38 AM »

I fixed it!  Still don't know what the problem was or why what I did fixed it, but at least it's working now!

While checking the balance control as suggested by someone earlier, I accidentally put the radio in monoband mode.  When I did that, the UHF side started working.  I put it back in dual band mode and now everything is back to normal.  For now anyway. 

I'm starting to see why the FT-8100 has such a bad reputation!!
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K1CJS
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« Reply #11 on: July 11, 2013, 06:20:09 PM »

So the problem could be either the switch that puts it in monoband mode or anything that changing that switch affects.

Now I see what is meant by a 'problem radio.'

Well, I'm glad you got it working, anyway.  73.
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K4NYA
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Posts: 43




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« Reply #12 on: July 14, 2013, 09:58:13 AM »

And now it's not working again!  *sigh*  I see a new radio in my future...
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