TK-X180 mobile cross-band repeat, here's how...

[ramal121]

I got a PM asking me how to connect two Kenwood TK-X180 mobiles to do cross band repeat.
I've been meaning to reply to that. Since I had to do one today, I thought I would write
this up and put it on the forum for anyone who would like this. It's quite simple for
anyone with the least amount of wiring/solder skills. Parts required are 2 DB-25 male
connectors, 2 DB-25 hoods, 2 miniature volume pots, 2 5.6K resistors, and a chunk of
shielded cable with at least 4 wires plus drain wire (you need all five).

The idea first is to cross two logic lines between radios. I use I/O-1 PTT (to key the
radio) connected to I/O-2 COR or TOR (a receive indicator to key the opposite radio).
This is done on both radios. Second, is to cross receive audio to the mic input of
both radios. Lastly, connect shield wire ground (pin 7) to ground (pin 7).

In this Kenwood radio, receive audio is waaaay too much to put directly into the mic.
I pad the audio down with a 1.0K pot and a 5.6K resistor. The two outside terminals of
the pot connect to MI2 (mic) pin 6 and ME (mic ground) pin 25. The center terminal of the
pot (wiper) goes to a 5.6K resistor. The resistor then connects to the wire that goes to
the receive audio (AFO) of the other radio, pin 17.

In the radio programming, you will need to program I/O-1 (input/output) as input and PTT.
I/O-2 needs to be output, either COR (carrier detect) or TOR (carrier + CTCSS detect).
Both I/O's need to be active low.

Pic one is the wiring diagram. Pic 2&3 show assembly. I hot glue the pot in place. There
is also a hole drilled into the hood to access the pot for adjustments.

To adjust, turn the pot all the way down. Have someone transmit a test count on one freq,
(have them speak up, no wispering), you listen on the other freq and turn pot until volume
just comes up to max and no more. Usually about a 1/4 to 1/3 turn. Any more and it will
just get more distorted. Swap radios and do the other side. That's it.

This diagram is for an "on all the time" bi-directional repeater, which is what I'm using.
To make it selectable, simply break the two I/O lines between radios and run them up to a
dual pole switch. This would give the user on/off control of the x-band repeater.

[talexhill]

i'd like to try this with a Kenwood NX-800(H) and NX-700(H). could you email me higher resolution images, and or any updated instructions you might have? talexhill@me.com


Thanks,

T Alex

[kg4uad]

That's pretty trick. I have a soon to be shelved 7180 and it makes me wonder if i were to spring for a nx-700 (for rx and RAN) and tune up a duplexer if it would make a nice NXDN amateur repeater. Anyone know if the 7180 would pass digital if bandwidth was programmed to 12.5khz narrow? I'm thinking it should.

thanks
Matt R.

[phillydjdan]

I just finished making my cross band cable for my TK-7180/8180 pair. Works great, although it appears about a half second of audio gets chopped off the beginning of the transmission. Is there any possible way to remedy that, like a setting in the software? My next project is to try this with a pair of NXs....

[MTS2000des]

Now if Kenwood would just build in the "ID feature" of the V71A, it would be legal to use this on Part 97 full time. Still have to work out how to make it ID.

[n7maq-1]

How do you keep radio A from keying up if radio B is powered off? That is a problem if you interface the radio directly like that.

Jim

[phillydjdan]

I added a toggle into my cable, and I would suggest others do also.

[obijohn]

Originally Posted by MTS2000des

Now if Kenwood would just build in the "ID feature" of the V71A, it would be legal to use this on Part 97 full time. Still have to work out how to make it ID.

Just install an ID-O-MATIC II from HamGadgets, Interesting Gadgets for Radio Amateurs. They are $25.00. Dale makes some neat stuff.