Kenwood Installation Cable extension question

Tiktaalik

Supporting Sponsor
I bought a Kenwood TM-D710GA and need to extend the RJ-45 cables for the mic and operation panel going to the TX/RX unit.

I want to get this extension:


but I read somewhere that you’ll get interference if you don’t use Kenwood specific RJ-45 cables.

Is this true? Has anyone extended the mic and control panel cables successfully using generic RJ-45 cables without interference?
 

pagero

New member
Haven't extended the cables, but I use a regular CAT6 between the control panel and the main radio unit. Found one on Amazon with a flat cable & a 90 degree angle on the control panel side, makes the cable a little less obtrusive. Have not noticed any problems.
 

Recommended books for Overlanding

Tiktaalik

Supporting Sponsor
Ok! I’m gonna give it a go. I’m getting the panel mount extensions as I want them flush mounted to the dash. Thank you!
 

spressomon

Expedition Leader
FWIW: https://forums.radioreference.com/threads/kenwood-vm71a-question.380860/

And: https://forums.radioreference.com/threads/does-my-d710a-need-repair-or-am-i-an-idiot.239993/

The problem I'm having with my TM-D710A is intermittent noise when the radio is on but not RX/TX. I swapped in the Kenwood connector cable instead of the generic CAT5/6 I was using and it seems to have reduced the problem but not eliminated the problem. Now wondering if its a mic issue since hitting the PTT button on the mic will generally resolve the problem.

Sound quality for those receiving my transmissions is very good.
 

DaveInDenver

Expedition Leader
In my experience with Kenwood and radios that use Kenwood mics (such as some Chinese manufacturers) there's two major things to concern yourself with.

First is the general likelihood for RF interference on any cable. In this case both cables have low level signal that may be susceptible to noise so using cat5/5e/6/etc cable may or may not work. It helps to use shielded or perhaps twisted pair cable and ferrite snap-on chokes but generally your typical best practices applies here.

The seconds is the more irritating and harder to deal with problem since it's specific to the mic pinout and cable itself. Using plain parallel 8-conductor wire on a Kenwood mic is risking bad interference. This is due to the mic signal itself, pin 6, and the DTMF signal also running in the cable. The DTMF is serial data and it's easy to get noise to couple onto the mic line. I've never had luck using a parallel (no twisted pair) cable (standard length coiled or extended) on a Kenwood mic with DTMF. Plain mics without a keypad usually work alright regardless of the cable.

Within better Kenwood mic cables you'll see use of a tiny coaxial cable for pin 6 with the shield grounded to pin 5 next to it. If you look really close to the 8P8C connector it's the white wire 3rd from the top-left and the shield is to the right.

81w0cVe3H+L._SL1500_.jpg

I've never cut open a genuine Kenwood extension cable to see what they do, whether its to use a shielded wire in the bundle or what. But at least using wire that either continues the shield for this signal or at least pairs and twists the wires for pins 5 and 6 would be important.

I think the various degrees of success or failure with Ethernet cables probably depends on whether the person is using FTP, UTP or STP. Generic UTP (e.g. no shields of any kind) cables probably cause lots of issues while different FTP or STP will end up less prone.

At least having individual pairs shielded from other pairs (U/FTP) is OK and probably critical for the mic. Having an overall shield can't hurt (F/FTP or S/FTP). And then the question comes up as to whether the connector is grounded to anything that would give an overall shield anything to connect to. I don't know that.
 
Last edited:

dreadlocks

Well-known member
I just used some standard CAT6e I had lying around, put a punch down box on one end and a crimp on another... then a choke right out of the radio.. Sounds great on my D710G
 

DaveInDenver

Expedition Leader
I just used some standard CAT6e I had lying around, put a punch down box on one end and a crimp on another... then a choke right out of the radio.. Sounds great on my D710G
Cat6e isn't an actual specification (perhaps you mean 6a) so what was the cable? Sounds like plain UTP. So was this for both cables? Do you use a DTMF mic and has no one mentioned a buzz on your transmitted audio? The face extension cable isn't hyper critical and a choke should be all it takes. It's just the mic extension where you have to be highly aware of the mic line interference and that happens within the bundle so a snap-on choke isn't always going to sufficiently attenuate it.
 
Last edited:

dreadlocks

Well-known member
ah yeah thats what I get for typing before morning coffee... just standard cat6, non shielded.. it does have an isolator inside to keep the pairs separated.. I use the DTMF mic and audio sounds perfect.. I just used normal T568B, didnt realize Kenwood did anything different.

There was a little buzz when I first tested it, but then I slapped the choke on and all that went away.. crystal clear audio, 5x9s all the time.. My Radio is in the spare tire area in the back, got 2 runs of ~15ft going under the carpet and up the center console.. pulling unterminated ethernet is much easier than pre-fab cabling.
 

DaveInDenver

Expedition Leader
Huh, interesting. I have to use S/FTP to keep from sounding like I'm running a chain saw in my truck. Must be the difference between a Toyota and an Audi. I even have my antennas on the roof so it's not an RF-rich environment inside the cabin. My runs are from the dash to the passenger seat, so hardly excessively long even.
 

dreadlocks

Well-known member
You could be on to something there, I've got a DC charging system from the factory.. I dont think any of my electronics are exposed to the raw alternator output so its likely getting cleaner power w/less RF noise.. Ive got onboard hotspot/3g cell/433Mhz remote for Webasto and probably some other things inside the cabin.. my antenna is mounted to my frontrunner rack because I'm too chickenshit to drill into my Aluminum roof on such an expensive vehicle.

I'm on my 4th spool of CAT6 in my house so I just used what I had laying about, but if I were gonna go buy some cabling for this job I'd definitely go grab some shielded stuff out the gate.
 

DaveInDenver

Expedition Leader
Yeah, a 2008 Tacoma certainly seems to not get the attention to detail in design or testing w.r.t. EMI/EMC as an Audi.

The problem that has been a real thorn is the DTMF interference, though. The only solution that's been reliable is to use a Kenwood KMC-27 mic and genuine commercial cable. On DMR the serial noise renders my radio unusable since it seems to really trip up the vocoder.
 

uli2000

Adventurer
I had some interference using a regular RJ45 coupler on the mic of my D710A. By switching over to a shielded RJ45 coupler, it got rid of the interference. I don't remember having any issue with the head cable.
 

Recommended books for Overlanding

Vehicle-dependent Expedition Guide
by Tom Sheppard
From $133.57
999 Days Around Africa: The Road Chose Me
by Dan Grec, Dan Grec
From $19.95
Crossing the Congo: Over Land and Water in a Hard Place
by Mike Martin, Chloe Baker, Charlie Hatch-Barnwell
From $30

DaveInDenver

Expedition Leader
Now you made me go back and look at the cable I'm currently using between the display and the main unit... It's this one from Amazon: https://smile.amazon.com/gp/product/B076PCCGMX/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&th=1

It's a flat cable, and from the looks of it I'm guessing each pair is twisted. It also says it's double shielded, shielded overall and shielded for each pair.

All that said, I'm using this for the display, not the mic.
You link to a cat7 flat cable. Cat7 is a strict standard and to meet the noise immunity, radiated noise and cross talk standards it requires foil on the pairs and an overall shield (e.g. F/FTP or S/FTP), so it's a good option.
 
Top