Kenwood TK 790H Questions and Troubleshooting

[peq387ab]

Hello,

I inherited a few Kenwood TK 790H with the remote head basic function with 5 programmable buttons. I have some questions and also ran into a little roadblock.

First question I have is installed into my pickup and I noticed that after programming it, their is no audio that come through the remote head speaker. And when I transmit on simplex it sounds clear but when I went to transmit through the repeater it was muffled. What is the culprit to fixing these issues?

Also secondly, I did program some Ham frequencies into this radio, even though it gave me a warning error, they still seem to have worked? Anyone have had luck with this?

Thanks in advance. Biggest question is I have is what I should be doing to get that audio problem fixed. Thanks!

 

[tweiss3]

First question I have is installed into my pickup and I noticed that after programming it, their is no audio that come through the remote head speaker. And when I transmit on simplex it sounds clear but when I went to transmit through the repeater it was muffled. What is the culprit to fixing these issues?

I don't have this radio, but I have two TK-8150, and one of them had that issue. It was either one of the pins in the remote head cable pulled out, or the ground screw didn't get re-attached.

Also secondly, I did program some Ham frequencies into this radio, even though it gave me a warning error, they still seem to have worked? Anyone have had luck with this?

If you are getting out and making contact on a repeater, I'd call it working.

 

[peq387ab]

Okay, I was wondering about that if it had to do with those remote head pins from the remote head to the radio brick. I can pull those ends off tonight after work and look them over to see if something is loose within those. I was finding it odd I was able to TX with simplex and hear on my portable but their no audio coming on RX through the remote head and in addition the repeater was garbled when I transmitted.

 

[mmckenna]

First question I have is installed into my pickup and I noticed that after programming it, their is no audio that come through the remote head speaker.

There should be a jumper plug on the rear 9 pin connector of the RF deck. If that is not installed, it won't send audio to the internal speaker. That jumper plug would connect pins 3 and 6 and pass the audio amp output to the speaker on the KCH-10 control head.

And when I transmit on simplex it sounds clear but when I went to transmit through the repeater it was muffled. What is the culprit to fixing these issues?

Do you have your radios programmed for wide or narrow deviation? These radios will do narrow (12.5KHz channels/2.5KHz deviation) and wide (25KHz channels/5KHz deviation). If you are using a wide band repeater (most amateur analog repeaters are wide band) a narrow band programmed radio will sound like it's muffled. Check your programming.

Also secondly, I did program some Ham frequencies into this radio, even though it gave me a warning error, they still seem to have worked? Anyone have had luck with this?

As long as the VCO doesn't unlock, it shouldn't be an issue. These radios can be taken a bit out of band, and down to 144MHz shouldn't be an issue. If you go to far, performance can be impacted due to the way the filters are tuned, and ultimately the VCO can unlock and the radio just won't work. But, sounds like you are OK.

Thanks in advance. Biggest question is I have is what I should be doing to get that audio problem fixed. Thanks!
[/QUOTE]

 

[mmckenna]

...and in addition the repeater was garbled when I transmitted.

If your receiver is too close to the transmitting radio, it can overload the receiver. Make sure the radio you are transmitting with and the one you are receiving with are well separated.

 

[peq387ab]

There should be a jumper plug on the rear 9 pin connector of the RF deck. If that is not installed, it won't send audio to the internal speaker. That jumper plug would connect pins 3 and 6 and pass the audio amp output to the speaker on the KCH-10 control head.



Do you have your radios programmed for wide or narrow deviation? These radios will do narrow (12.5KHz channels/2.5KHz deviation) and wide (25KHz channels/5KHz deviation). If you are using a wide band repeater (most amateur analog repeaters are wide band) a narrow band programmed radio will sound like it's muffled. Check your programming.



As long as the VCO doesn't unlock, it shouldn't be an issue. These radios can be taken a bit out of band, and down to 144MHz shouldn't be an issue. If you go to far, performance can be impacted due to the way the filters are tuned, and ultimately the VCO can unlock and the radio just won't work. But, sounds like you are OK.

Thanks in advance. Biggest question is I have is what I should be doing to get that audio problem fixed. Thanks!

[/QUOTE]

I do have the 9 pin jumper on the controller. I looked at that, there is a pass that goes from one to other, I didn’t install it, came like it. Pulled it out and tried two different jumpers, no luck still with audio. Maybe I have it in the wrong pin slots? Sorry, I haven’t had much experience with Kenwood as I had with other commercial brands. Do you think that data line from the power controller to the head could be bad and/or loose? Oddly enough the unit will transmit radio to radio but no RX

 

[mmckenna]

I do have the 9 pin jumper on the controller.

The 9 pin connector would be on the back of the RF deck, not the control head. The control head has a 12 pin connector. Just want to make sure we are talking about the same thing. Pins 3 & 6 should be jumpered for the internal speaker to work.

How do you know it's receiving? Is the LED illuminating on the control head? Just want to make sure it's not a CTCSS tone error.

 

[peq387ab]

The 9 pin connector would be on the back of the RF deck, not the control head. The control head has a 12 pin connector. Just want to make sure we are talking about the same thing. Pins 3 & 6 should be jumpered for the internal speaker to work.

How do you know it's receiving? Is the LED illuminating on the control head? Just want to make sure it's not a CTCSS tone error.

sorry, yes we are talking about the same thing. I just tried uploading a picture. Said too big

 

[peq387ab]

But yes that 9 pin is connected to the rf deck.

 

[peq387ab]

Sorry, i know it’s receiving because they busy light illuminates.

 

[mmckenna]

Sorry, i know it’s receiving because they busy light illuminates.

OK, and do you have it set to carrier squelch? I know you probably checked this, but it's always good to run through the obvious.

 

[peq387ab]

Correct, the frequency I tested was in CSQ. I had the squelch level at 7 and volume at 70%

 

[mmckenna]

OK, thanks for confirming, I've fat fingered programming before and messed things up. Make sure none of the buttons are programmed for PA function.

So, if the 9 pin plug is installed and the jumper is there between pins 3 and 6, that should route speaker audio to the control head.

Next thing to check would be the cable from the radio to the module where the control head cable plugs in. It has two leads for the speaker.
Check the remote head cable for damage, bent pins, etc.
Same with the rear of the control head. Check for loose connections, bent pins, damaged cable, etc.

Open up the control head, and make sure the speaker is plugged in. Just in case it came loose or was disconnected by someone...

If it's not one of those, and you are 100% sure the programming is good then you'd probably want to start looking at the audio PA. That's beyond what I can assist you with remotely. I have a service manual I can drop-box to you if you want to send me your e-mail address via private messages.

 

[peq387ab]

Thanks for the info. The data cable from the head to the unit looks good and is seated in well. The rear of the remote head has two black wires if you look at it from the back plugged into the bottom left two and a red wire to the top left on the 9 pin at the back of the remote head. What I’m wondering is since I don’t have a diagram, are these pins at the main radio from the 9 pin power supply and the white two jumper flipped around or not correct in that white jumper line.

 

[mmckenna]

Looking at the 9 pin connector on the rear of the radio deck, the pins are numbered like this:

3 6 9
2 5 8
1 4 7

There should be a jumper wire between pins 3 and 6 to make the internal speaker work.

Pin 1 is for ignition sense. If set up correctly, that would turn the radio on/off with the vehicles ignition.

 

[n3obl]

One big issue with the 790 was they were not tuned properly from factory for Narrow banding. I recommend these unit be placed on a service monitor and perform a full tuning on the unit prior to placing back in service.

 

[peq387ab]

Okay. This is making more sense. Those pins are reversed for some reason on thats diagram looking at the unit. Is there a trick for pulling those out to swap them around?
Yes I setup the unit to power on/off with my pickup

 

[peq387ab]

If I look at the 9 pin with the grooves on the left side of the diagram, they are in the 1 & 4 slot right now

 

[peq387ab]

Okay. I was able to make sure the pins were in the correct spot. I moved them around to double check but they were in the correct spot of 3 & 6. Still can transmit out and voice is heard, but no still no receive voice on this unit. I’m wondering if it’s something bad with this specific unit internally? Bad wire or speaker?

 

[mmckenna]

3 6 9
>
2 5 8
>
1 4 7

Pin
1 Ignition Sense Input
2 BTL output for external speaker a
3 Remote Speaker Switch
4 Horn alert signal output 1
5 Horn alert signal output 2
6 BTL output for external speaker A
7 BTL output for external speaker B (PA)
8 BTL output for external speaker B (PA)
9 Earth/Ground

Open the control head and make sure the speaker is connected. There's a two pin cable/connector that runs from the speaker to the circuit board.