TK-830 Quiet Rx, No Tx

[Nighthawk98TJ]

Hi All,

I just picked up a Kenwood TK-830g UHF from a friend out of his truck that was working properly in that vehicle. I have now installed it in my vehicle and I am having some issues. When I receive audio, it is VERY quiet... I have to turn up the external speaker all the way to even barely hear it. Also, when transmitting, I can touch a repeater and get a response back, but I am unable to transmit anything but static.

At first this sounded like a coax/mount/antenna issue, but I have tried a completely different piece of coax on a different mount with a different antenna and I get the same issue. I have also tried a different speaker and I get the same quiet Rx issue. I believe everything is installed correctly and the audio that is being received is very clear, it's just VERY quiet and Tx is useless. I have also checked the power connection and it appears to be good and has a good ground. Any ideas on why this might be occurring?

Thanks,

Tim

 

[Nighthawk98TJ]

OK, so I solved the TX problem, however, I am still getting VERY low volume on RX... so low that it's hardly audible when the volume on the unit is maxed out. However, the warning beeps from the system are at the proper volume, it's just the audio from the radio that is low. It is, however, quite clear. The problem is not the external speaker as I've tried a different speaker and get the same results. Any idea what this problem would appear?

 

[ramal121]

Is this a dash mount radio or a remote mount with a cable? If it is a remote mount, I would recheck the
cable connectors at the head and chassis, make sure they're seated firmly.

 

[Nighthawk98TJ]

It's a remote mount with a cable. I have checked the connections at both ends numerous times and I've even tried a different cable and still have the same problem... thanks!

 

[ramal121]

OK. Getting those cable connectors down tight is a common install goof. The only other one I can think of is the speaker jumper on the back of the radio (if you plug speaker into control head). But this would not be the case because you stated the control beeps are fine.

I assume that as you press buttons, the beep is normal and goes up and down with the volume control. But if you press and hold the monitor button (to blow open squelch) it is very weak at high volume and goes to nothing as you turn the volume down. This would indicate that the volume control, audio PA, and connections out to the speakers are OK.

There is an IC (IC103) on the control board that does all of the audio processing. Detected receive from the RF board and the beep tone from the uP go there. Also squelch and QT logic end up there for audio control. It's all mixed up, filtered, and sent out as signal AFO to the audio PA and speaker. I suspect your problem lies around IC103. The only way to be sure is to open the radio and get your hands dirty. The audio levels in and out of the IC need to be checked to see where the problem is.

Anybody else have any ideas?

 

[Nighthawk98TJ]

OK. Getting those cable connectors down tight is a common install goof. The only other one I can think of is the speaker jumper on the back of the radio (if you plug speaker into control head). But this would not be the case because you stated the control beeps are fine.

I assume that as you press buttons, the beep is normal and goes up and down with the volume control. But if you press and hold the monitor button (to blow open squelch) it is very weak at high volume and goes to nothing as you turn the volume down. This would indicate that the volume control, audio PA, and connections out to the speakers are OK.

There is an IC (IC103) on the control board that does all of the audio processing. Detected receive from the RF board and the beep tone from the uP go there. Also squelch and QT logic end up there for audio control. It's all mixed up, filtered, and sent out as signal AFO to the audio PA and speaker. I suspect your problem lies around IC103. The only way to be sure is to open the radio and get your hands dirty. The audio levels in and out of the IC need to be checked to see where the problem is.

Anybody else have any ideas?

Thank you for the detailed response. With the squelch open, the problem persists and all beeping audio is at proper volume. Regarding IC103, is an analysis of this IC feasible for a non-professional? My other option is an amplified speaker to boost the audio. Any ideas?

 

[ramal121]

Yea you could put a amplified speaker on the output. Listen, I've done some pretty weird $h!t in my time, but at normal volume, the beeps would rip the speaker cone and blow out your eardrums.

Per the book, this is how it goes. You need a signal generator set to the freq you are testing on, and have a signal level fairly high so there is not much static. The generator has to be modulated with a 1000Hz tone at 3KHz deviation ( a little more than half transmit volume). With this setup, you can use a oscilloscope or AC voltmeter to probe different points in the radio and compare them with the readings that are printed on the schematic from Kenwood.

Works for me but I can see your eyes rolling! I fix these things to pay my mortgage. Am I a professional? Jeez, I don't know. Are you a non-professional? I don't know. You had the nads to check into this forum, so I assume you would like to figure this out to the best of your abilities.

Here's what I can do. Can you beg, borrow, or steal a digital voltmeter, One that reads an AC only component? If so, I could show you where to check and what readings you would expect if you open the squelch and measure the white noise. I do not have a 830 that works, but I could use my 730, on which the control board is the same.

How do you know if a voltmeter reads only AC component? Get one and set it for DC volts (usually 20). Put it on your car battery. Reads 12.8 volts (or whatever). Now switch it to AC volts at the lowest setting (usually 2 volts) and stick it across the car battery. If it is zero or real low (0.1 V), it will read only the AC component.

If you're up for this, maybe we can figure this out. If not, check for a Kenwood shop that could take a look at it.

 

[Nighthawk98TJ]

Yes! I would appreciate the troubleshooting help. Before we begin, if we do find a problem with the radio, is it likely I would even be able to correct it myself?

Back to the radio, my voltmeter has pretty high AC voltage settings (200 is the lowest) and mt cad battery reads 25.7 on that setting. Will that work or will I need to borrow a better meter?

Next, what are the first tests I should conduct on the unit?

Thanks for the help, I appreciate it!

Tim

 

[Nighthawk98TJ]

I fooled with the radio quite a long while today and still did not have any luck. For some reason, the amplified speaker I used did not seem to yield any improvement at all. This is driving me nuts... any ideas?

 

[Nighthawk98TJ]

Problem solved! I found something that was broken on the board when doing my 500th inspection. I fixed the connection and all is well again! I'm not even sure what the item was, but it was basically a small wire loop with something that looked like a resistor on one one, but it wasn't a resistor. The wire loop was blown/broken, so when I fixed that everything was well! Thanks for the help everyone!