Timz

DMR Repeater

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Other D578 info  How-To section

 

  

Interfacing a SignaLink USB to a D578

Part One

 

 

This is a little tricky, as the D578 does not have an AUX I/O port. But, there is still a way to interface the SignaLink USB to operate a D578 radio by installing an AUX I/O jack in the handmic (which has all the necessary signals inside).

NOTE: a newer firmware version allows for a pull-to-low PTT signal to be present on the radios mic jack via a selection in the CPS. Only negative to this is... in order to switch back to hand mic operation.... you'll need to reprogram the radio to non pull-to-low PTT operation.

The method below negates the need to reprogram the radio when switching between the hand mic and Signalink.

 

Click HERE for video of a D578 operating through a Signalink USB.

 

This method works fine; and below are the details.

 

FAQ First:

* Is this the only method for operating a SignaLink USB from a D578?

I hope not, but this is the first method I had success with. If you find another way, PLEASE SHARE IT with your fellow hams. I know one ham with an idea to install a BT module inside the SignaLink.... and communicating to the D578 via bluetooth connection. It will be cool if this works! But for now, I have documented my brute-force shotgun approach below.

* Does this method work on all SignaLink USB units?

Maybe - maybe not. My Signalink USB is setup to work on an Icom IC-7000, and the original configuration performed to my Signalink USB is for my Icom. I did not need to change anything in the SignaLink to get the D578 working. I can easily switch back to my Icom by swapping the cable in the back of the SignaLink. It works perfectly each and every time.  FYI, my SignaLink USBs "connector board" is a SLMOD6PM. This is covered more indepth on the Part Two page.. Adding the jack to the handmic is the same regardless; but the cable from the AUX jack to the SignaLink will be different depending on which Connector Board is installed in you SignaLink USB.

* Is there a drawback? (there always is... right ?)

Yes, the handmics mic-element is live when the SignaLink USB is in transmit mode. Through extensive testing - I found no issues at all with this. I was going to place a small 5v relay inside the mic to disconnect the internal mic-element when the SignaLink was PTT'ing, but never found the live mic to be an issue during data transmission.

* Is this a safe modification?

This is obviously an "at your own risk" procedure.

* I showed this to (insert name) and he said you are "full-of-it..."

Hey, no problem. Just ignore this web page and find some other method yourself. This works perfectly for me; but do whatever you want to and enjoy the hobby.

 

Summary

* prepare a 4 conductor 3.5mm jack for installation into your D578 handmic

* drill hole for AUX jack to protrude through

* Make cable... with matching 3.5mm plug on one end, and a RJ-45 plug on the other end (which plugs directly into your SignaLink USB)

 

for Part Two "CASE PREP & CABLE Assembly" instructions- click HERE

 

The four connections needed for the SignaLink USB are:

* GND
* PTT
active low for this application
* TX Mod
* RX audio

These are all present inside the Anytone D578 wired handmic (rear case half removed):

after a lot of searching I found a 3.5mm 4 conductor jack that fits (barely) inside the mic case:

Digi-Key SJ1-43502PM

 

below is the type of plug that mates with the jack:

Note: I found a cable on Amazon that has a nice molded 3.5mm connector on the one end. This makes it easy to install a RJ-45 on the other (SignaLink) end. This is covered and linked to in Part Two. 

 

you will also need two 1/4w resistors (these values matched the TX mod level and RX amplitude as on my Icom IC-7000; allowing me to swap cables going to the SignaLink between the 7000 and D578... without needing to readjust the level settings on the Signalink USB front panel).

* 3.9K (or 4.7k) in series for the TX modulation connection
* 1k
in series for the RX audio connection

 

Note: the wire connections are to the internal circuit board (front case area), but the jack is mounted in the rear case half. More on this in Part 2.

 

Prepare four wires to go from the circuit board locations to the 3.5mm 4c jack. Two of the wires will have resistors inline. Pre-tin both ends of the wires and the resistors:

* GND wire 2"
* PTT 3.5"
* TX Mod 3" (then add 1/4w 3.9k resistor in series; or 4.7k)
* RX audio 2" (then add 1/4w 1k resistor in series)


The wires with
LARGE ends ... those are the ones that have resistors. They have been heatshrinked.

jack wiring orientation:

 

 

Three of the four total wires are easily soldered to the proper places on the circuit board; the fourth, (PTT) needs a little extra effort. I will show that one first.

 PTT connection

this wire is soldered directly to the PTT switch, on an exposed terminal coming out of the top of the switch (blue dot). First though, you need to bend the mounting lug away from this exposed terminal a little bit; just to give some clearance:

note: the pic shows an exaguration of the amount needed to offer some clearance (distance) between the switch terminal and the side mounting piece.

then tin the exposed terminal , and then solder the AUX I/O PTT wire to this location..

 

TX Modulation connection

This added wire will have a 3.9k or 4.7k resistor in series (connect here or to the existing red wire):

 

RX Audio Connection

This added wire will have a 1k resistor in series:

leave the existing red wire as originally connected.

 

Ground Connection

solder your jacks ground wire to this location:


Click on pic for larger version. See Part Two (below) for jack hole location and SignaLink cable assembly.

 

 

PART TWO: for CASE PREP & Cable assembly instructions- click HERE

 

 

 

Tim N8NQH

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