Notes on interfacing the Tigertronics SignaLink to the Yaesu FT-817 radio - K9JRW
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I obtained the SL1-NC model SignaLink (comes with Unterminated cable)
via www.tigertronics.com
for interfacing a Yaesu FT-817 

I decided to interface the SignaLink to the FT-817 via the Data port
on the back of the radio. Probably could have gone the Mic connector
route also but thought since the data port was available it would
be better.

I had a CT-39 cable from Yaesu for the data port. (Probably could have
used any old PS2 cable for this).

First order of business was splicing the unterminated RJ45 cable for
the SignaLink to the CT-39 DIN cable. Since the SignaLink needs to
have the cross connects jumpered inside it, I just connected the cables
straight thru - i.e. Pin 1 to Pin 1 etc. This ended up being:
SignaLink SLCABNC    Yaesu CT-39
-----------------    -------------------
Pin 1 White/Orange<->Pin 1 Black  (TX Audio)
Pin 2 Orange      <->Pin 2 Brown  (GND)
Pin 3 White/Green <->Pin 3 Red    (PTT)
Pin 4 Blue        <->Pin 4 Orange (9600 bps data)
Pin 5 White/Blue  <->Pin 5 Yellow (1200 bps data)
Pin 6 Green       <->Pin 6 Green  (Squelch status)

Once the cable was made, I did a sanity check by buzzing out a few things
and once convinced it was right performed the jumpering in the SignaLink
box. On the 8 pin dip jumper block I jumpered:
Pin 1 -> MIC
Pin 2 -> GND
Pin 3 -> PTT
Pin 4 -> N.C.
Pin 5 -> SPKR
Pin 6 -> N.C.

I was hoping that maybe the Squelch status line would be sufficient for
powering the SignaLink, but it ended up being a 5V signal which isn't
high enough for what the SignaLink needs. The other possibility I thought
about was jumpering over the 13.5V accessory voltage source to the Yaesu
data connector but didn't want to make my interface rig specific. (So
i ended up just using a wall wart to power the SignaLink when i wanted
to TX and RX.)

After a few more sanity checks I hooked everything up and started operational
testing.

First thing I noticed was the audio line isolation really worked nicely. Much
better (i.e. no effect) than an audio cable straight from radio to computer. The
receive audio at my computer was fine using either the MIC or LINE level inputs.

For PSK31 I switched the Yaesu to the DIG mode and using Menu Item 26 in the 
radio to set the DIG MODE to USER-U. (I had read somewhere about a 10Hz shift 
when transmitting if I using the PSK31-U mode). 

RX Audio came in fine and using Hamscope or Digipan software I was able to decode
signals just fine. 

Now for transmitting. The SignaLink performs a VOX operation to decide when to
drive the PTT line into the Data port. I switched the Yaesu meter function over
to ALC and gave it a go. The SignaLink did the job and activated PTT whenever
the computer was generating tones*, but I never saw any ALC movement. I tried
using Menu Item 25 to adjust the input level, but still no ALC on the meter. 
I believe things may have been OK even with no ALC meter indication, but decided 
to perform the TX Gain mod on the SignaLink using their notes here:
http://www.tigertronics.com/sl_mods.htm

After performing this mod I had ALC meter action of about 6 bars on the 50 level 
DIG MIC setting. FWIW, the DIG MIC could be set all the way down to about 18 without losing
this level.

* The only possible weirdness i see is if my PSK31 transmit audio frequency is below
about 750 Hz, I do not get a PTT activation via the SignaLink. This is easily solved by tuning
the radio a bit lower. 

I am very impressed with the quality of the SignaLink unit and documentation. The web
site is also very useful. I think the price of the unit is fair and represents a good
value. I have used the unit to now make my first PSK31 contacts (including 2 overseas
countries) and am very happy with its performance interfaced to the Yaesu FT-817.

Jay
K9JRW
k9jrw@arrl.net