adding intercom and external mic/ptt/speakers to Kenwood TK-790H

[steves08gxp]

Hi everyone

Thank you again for the help with my previous questions but i now have a new one lol

I have a polaris RZR that i installed a 790 in. It works awesome but after a group ride this last weekend the wife wants helmet air and closed helmets.

That means intercoms, ptt buttons and wired helmets....

I bought the PCI Race Radio helmets and i purchased a "rugged radios" (i know their reputation on here) intercom used. I only went with this one because i got it for a hell of a price.

Im waiting for it to arrive but im trying to plan out my integration when it does arrive. I ordered this cable from rugged radios which gives me the 5 pin connection off of the DB25 off the back of the transceiver.

Kenwood 9-Pin Mobile Radio Jumper Cable

Complete your communications with this mobile radio jumper. Connect your 2-way radio to your wiring harness, intercom, or cabling setup. This jumper works with: Kenwood TK-790 110W Mobile Radio

www.ruggedradios.com

My questions start with programming...

I found an old post on here that said i need to turn "FUNCTION PORT" -> "RADIO 1 AI1" should be set to "EXT PTT".

Is this correct even for this setup? I asked rugged and they didnt know...

The other question i have, is will my old external speaker and hand held mic work if i turn the intercom off?

Thank you in advance

 

[ramal121]

There are 5 inputs (and also 2 inputs on a remote head). You need to set one of those to EXT PTT to transmit. Which one you use depends on how the interface cable was built. The manufacturer would need to provide that to you. If Rugged Radios can't explain then I don't give them high marks on support. If you still can't get the right answer, you could either take the 25 pin connector apart and see what pin a wire is connected to (pins 2-6), or just try to program each input one at a time. It would only take at most 5 tries to reprogram. Usually radio AI1 is used but not always.

The palm mic and speaker should work as normal. At least with all intercoms I deal with do. There's a huge gotcha though. The palm mic and the external mic on the DB-25 are one and the same inside the radio. This means when you transmit from the headset intercom the palm mic will be live also and you will get background engine noise, road noise, etc. mixed in on your transmission. Annoying. You can either leave the palm mic disconnected or there is a hack mod to make the mic element switched with its PTT button.

Also for headset operation you need to set these under Optional Features 1:

Ext PTT w/Mic Mute = uncheck
Ext PTT w/QT/DQT = check
Ext PTT w/Squelch Tail Eliminator = check

 

[steves08gxp]

There are 5 inputs (and also 2 inputs on a remote head). You need to set one of those to EXT PTT to transmit. Which one you use depends on how the interface cable was built. The manufacturer would need to provide that to you. If Rugged Radios can't explain then I don't give them high marks on support. If you still can't get the right answer, you could either take the 25 pin connector apart and see what pin a wire is connected to (pins 2-6), or just try to program each input one at a time. It would only take at most 5 tries to reprogram. Usually radio AI1 is used but not always.

I think just trying the different options might be easiest and quickest. I guess alternatively i could Ohm check no?

The palm mic and speaker should work as normal. At least with all intercoms I deal with do. There's a huge gotcha though. The palm mic and the external mic on the DB-25 are one and the same inside the radio. This means when you transmit from the headset intercom the palm mic will be live also and you will get background engine noise, road noise, etc. mixed in on your transmission. Annoying. You can either leave the palm mic disconnected or there is a hack mod to make the mic element switched with its PTT button.

Ah Ha! This is really good to know. The idea of using my handheld stuff is more of an just in case thing. Like if we are somewhere not wearing the helmets or whatever... Ill keep the mic disconnected in my glovebox.

Also for headset operation you need to set these under Optional Features 1:

Ext PTT w/Mic Mute = uncheck
Ext PTT w/QT/DQT = check
Ext PTT w/Squelch Tail Eliminator = check

This is great to know, thank you. ill look for these settings as well.

 

[ramal121]

An ohmeter would work too. If you can determine PTT on the 5 pin you can see where it winds up on the 25 pin.

Now I'll jump on my soapbox concerning headsets hooked up to radios. I've seen installs that seems like they just got the thing running and left it at that. No regard to audio levels. Nothing worst than "repeat that, you're all static". What exactly does that mean? What's wrong? Well have you attempted to set the audio levels for the best sound it can deliver? Sometimes not.

For receive audio it is usually fairly simple. The input goes across the speaker leads and the volume is adjusted by the radio. Sometimes there is a jumper for a high or low setting or it may have a pot for adjustment. No rocket science here. Set it for a comfortable listenable level and not have your eardrums shredded. Radio audio and intercom audio should be roughly equal.

Transmit audio is a little tougher. Different radios take different mic input levels. Kenwood uses dynamic mics which output 5 to 10 mV so it doesn't take much to drive the radio. Intercoms should have an adjustment so you can match what the radio will accept as normal. As you crank up the mic level from an external device you will find the transmit audio will get to a certain loudness and then stop. Attempts to increase from this level will not make it any louder but the audio quality will turn to crap. Starts to sound like you have rocks in your mouth and background noise increases. I have seen many set this way.

Now I use my service monitor to set transmit levels quick and easy, but if that is something you lack here is a way to earball it. you'll need another radio to listen to, preferably a handheld you can have right there. Listening on the second radio use the palm mic of the 790 to transmit some test audio. Using a moderately strong voice start with the mic right up to your lips (Covid 19 precautions apply here). Do the same with the mic 6 inches away, 12 inches away, and at arms length. Do this 2 or 3 times to get a feel for how the audio drops off as you move the mic away. Now do the same using the headset mic. Adjust the headset mic so both it and the palm mic has the same response and basically sound the same. The headset may have a noise canceling mic to where the audio fall-off maybe a little more abrupt so be prepared for that. But for god's sake don't go for maximum smoke. Under normal conditions the headset and the palm mic should sound virtually the same.

Good luck.

 

[mmckenna]

Great advice on setting the mic levels.

Also, you may already be planning to do this, but keeping a speaker hooked up so you can hear the radio with the helmets off. I used to use helmet mic/speaker when I was riding ATV's. It worked great, but as soon as you took the helmet off, you'd not hear anything at all. Easy to miss a call if you stop for a few minutes.
Maybe not a big deal, but I'd want a speaker hooked up so you can hear the radio without the helmets on.



Forced air circulation in the helmets is an awesome setup. Never had that on my Ranger, but I'd love to have it if I ever got a Rzr. I usually just end up with a bandana on under the helmet.

 

[n7maq-1]

I may have missed it, but you will also need to addrress a 0 Ohm resitor. You want to remove R641 and solder it on R640's pads.

Below is the hot mic mod from Kenwood.

Accessory Interface Instructions

KMC-27 “Hot Mic” Modification.
When installing an external headset or other type of external audio source it may be necessary to shut off the audio in the KMC-27 local microphone. This can be done using a transistor and 1 jumper wire. The Kenwood part # for the transistor is “DTA114ES” the ECG replacement part # is “ECG2356” The generic part # is 2SA1348. Open the mic by removing the four screws on the back of the mic. Locate C5, locate the trace shown in Fig 1. Cut the trace as shown in Fig 1. Scrape the green coating and tin the trace where that transistor is to be installed. Use an ohmmeter to verify that the trace is open. Solder the emitter and collector as shown in Fig 1. Solder a jumper wire from the base lead of the transistor to the PTT switch as shown in Fig 2. Test the modification by programming a function port for external PTT. Key the mic and verify the local mic passes audio. Next, ground the function port pin that was programmed for external PTT. Verify that the local Mic does not pass audio.




When testing is complete and proper operation has been verified cover the transistor with hot glue. Use another drop of hot glue to tack down the jumper wire to prevent excess vibration or breakage. The Mic must be reassembled carefully & correctly to retain driven rain & other environmental specifications.

Good luck and have fun.

 

[steves08gxp]

as shown in Fig 1. Solder a jumper wire from the base lead of the transistor to the PTT switch as shown in Fig 2. Test the modification by programming a function port for external PTT. Key the mic and verify the local mic passes audio. Next, ground the function port pin that was programmed for external PTT. Verify that the local Mic does not pass audio.

Thank you!

 

[steves08gxp]

An ohmeter would work too. If you can determine PTT on the 5 pin you can see where it winds up on the 25 pin.

Now I'll jump on my soapbox concerning headsets hooked up to radios. I've seen installs that seems like they just got the thing running and left it at that. No regard to audio levels. Nothing worst than "repeat that, you're all static". What exactly does that mean? What's wrong? Well have you attempted to set the audio levels for the best sound it can deliver? Sometimes not.

For receive audio it is usually fairly simple. The input goes across the speaker leads and the volume is adjusted by the radio. Sometimes there is a jumper for a high or low setting or it may have a pot for adjustment. No rocket science here. Set it for a comfortable listenable level and not have your eardrums shredded. Radio audio and intercom audio should be roughly equal.

Transmit audio is a little tougher. Different radios take different mic input levels. Kenwood uses dynamic mics which output 5 to 10 mV so it doesn't take much to drive the radio. Intercoms should have an adjustment so you can match what the radio will accept as normal. As you crank up the mic level from an external device you will find the transmit audio will get to a certain loudness and then stop. Attempts to increase from this level will not make it any louder but the audio quality will turn to crap. Starts to sound like you have rocks in your mouth and background noise increases. I have seen many set this way.

Now I use my service monitor to set transmit levels quick and easy, but if that is something you lack here is a way to earball it. you'll need another radio to listen to, preferably a handheld you can have right there. Listening on the second radio use the palm mic of the 790 to transmit some test audio. Using a moderately strong voice start with the mic right up to your lips (Covid 19 precautions apply here). Do the same with the mic 6 inches away, 12 inches away, and at arms length. Do this 2 or 3 times to get a feel for how the audio drops off as you move the mic away. Now do the same using the headset mic. Adjust the headset mic so both it and the palm mic has the same response and basically sound the same. The headset may have a noise canceling mic to where the audio fall-off maybe a little more abrupt so be prepared for that. But for god's sake don't go for maximum smoke. Under normal conditions the headset and the palm mic should sound virtually the same.

Good luck.

Thank you for this. I actually ended up calling PCI Race Radios today about something else and asked them about this while i was on the phone. They said they will modify the radio for 100 bucks and that will include the connection wire to my intercom, programming and mic tuning. Honestly for 100 bucks and because of my inexperience i feel its worth it.

They said the adapter cables dont usually work very long or well..... FWIW

With that said, i did make friends with the guy at a local radio shop who does have a service monitor and is willing to help me with the mic tuning and whatever else i need. But im thinking about just dropping it off with PCI and letting them deal with it. What do you suggest?

 

[steves08gxp]

Great advice on setting the mic levels.

Also, you may already be planning to do this, but keeping a speaker hooked up so you can hear the radio with the helmets off. I used to use helmet mic/speaker when I was riding ATV's. It worked great, but as soon as you took the helmet off, you'd not hear anything at all. Easy to miss a call if you stop for a few minutes.
Maybe not a big deal, but I'd want a speaker hooked up so you can hear the radio without the helmets on.



Forced air circulation in the helmets is an awesome setup. Never had that on my Ranger, but I'd love to have it if I ever got a Rzr. I usually just end up with a bandana on under the helmet.

Hey man! Thanks again for all your help previously.

I was planning on keeping the external speaker i have hooked up just might put it on a switch to turn it off when i am on the headset. I also plan on keeping the mic in the rzr basically so i have both options.

Im hoping the air is nice. We bought the PCI pre-wired "elite"helmets for the wife and I. The kids dont get to scream in our ears... We recently started doing group riding and to be honest the bandana was just not working well enough. Its dry out here in SoCal and since i have a pretty strong radio in this thing i end up running sweeper behind 10-15 cars... thats a lot of dust. That and im hoping the cool air helps cool us down because we have a full windshield and doors so we dont get much airflow through the car

 

[ramal121]

I may have missed it, but you will also need to addrress a 0 Ohm resitor. You want to remove R641 and solder it on R640's pad.

Yes,and that too. Slipped my mind. The default from Kenwood is the other way so most likely it will be required too.

Thank you for this. I actually ended up calling PCI Race Radios today about something else and asked them about this while i was on the phone. They said they will modify the radio for 100 bucks and that will include the connection wire to my intercom, programming and mic tuning. Honestly for 100 bucks and because of my inexperience i feel its worth it.

They said the adapter cables dont usually work very long or well..... FWIW

With that said, i did make friends with the guy at a local radio shop who does have a service monitor and is willing to help me with the mic tuning and whatever else i need. But im thinking about just dropping it off with PCI and letting them deal with it. What do you suggest?

Looks like everything you need is covered here. Easy enough for DYI. If you have someone with a service monitor that can help for the cost of a few beers that is definitely a plus but you will probably need to do some of your own leg work. To take it to PCI and have them set it up for you for a hun is really not a bad deal considering it may take them a good hour or so. The choice is yours...

 

[steves08gxp]

Looks like everything you need is covered here. Easy enough for DYI. If you have someone with a service monitor that can help for the cost of a few beers that is definitely a plus but you will probably need to do some of your own leg work. To take it to PCI and have them set it up for you for a hun is really not a bad deal considering it may take them a good hour or so. The choice is yours...

I ended up paying PCI 100 bucks to do the conversion. It was easier and they get to deal with any problems that arise. If any do....

Did super clean work too.

Got it all hooked up and it works great. Couple of weird things here that i wanted to ask here about...

1. The external speaker still works which is what i wanted. I put it on a switch so i can turn it on/off - this works great
However the speaker in the control head i cannot disconnect and still have receive audio in the helmet. It seems that i have to have it on and working for my intercom/helmets to have receive audio. I can transmit, use intercom. But Cannot hear radio transmissions if i disconnect the speaker in the head unit. IF i hook the speaker up everything works as expected.

I was wondering if i were to add a resistor to the speaker leads and clip the speaker if this would work? Meaning Tricking the headunit into thinking i have a speaker hooked up

2. The radio receive audio volume is kinda low. I'm assuming its because it comes off of the headunit and it is set to only put out 5watts. Per the service manual i can move a resistor and bump the head unit's output to 13w if i remember right. Would this help increase the volume heard in my helmet? Common sense says it should but i wanted to ask before i did anything.

Other than that the radio transmissions seem to be very clear and overall pretty happy with it. I think my Wife breathes on the mic or something because hers even with the intercom is kinda breezy if that makes sense. Mine however seems to be crystal clear

 

[steves08gxp]

I got bored and pulled it apart.... Figured i could always put it back how it was... Incase anyone is looking in the future...

For the speaker thing... the way that PCI modded the radio was to add to the control head, the wire for the thing they added. he said it was a transformer is wired in parallel with the speaker. I disconnected the speaker from the wiring and all works fine

As far as the receive volume. Moving the resistor on the control unit 100% fixed the issue. It is now quite loud and clear.

Thanks again for all the help here