The Tigertronics Signalink USB

Well,

Following my frustrations with the Yaesu SCU-17 rig interface back here:

http://g0mgx.blogspot.co.uk/2015/05/whats-going-on-here-then.html

and more here:

http://g0mgx.blogspot.co.uk/2015/05/whats-going-on-here-then-part-ii.html

I've been fiddling today with a Signalink USB interface. This suffers from similar issues to the Yaesu device, but there are a couple of excellent internet resources that help you fix it, here:

http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html

and here:

http://www.k7sfn.com/projects/signalink.html

So here is my Signalink half way through the fiddling process:

One of the most important mods in the link above is the replacement of a cap on the board with a 33uF value component. My Signalink already had 33uF onboard so this was left as-is.

What I have done is (documented on the links above), firstly added a 4.7uF capacitor to the power rails for the internal PIC:

I have also removed the 1K resistor feeding the audio circuitry power and fed the supply via 470R and the orange jumper wire you can see. This takes the power from the PIC regulator rather than the dirty USB supply. I have also added 47uF tantalum capacitor to the USB power supply:

That has improved the audio response dramatically and here is what we see post modification:

Now, the Signalink doesn't include an FSK switch to run RTTY, so I have modified the rig -> Signalink cable to bring the FSK keying line to an unused pin on the DIL internal socket, and wired that through a 4N32 opto-isolator to a 9 pin D-type connector I have added to the unit:

This connector can now take a Serial-USB adapter so I can run FSK from the PC.

I've also sold my FT-DX5000 and bought an ICOM IC-9100. I have fitted the optional 3KHz roofing filter and the 23cm module in the radio:

Freddie Cat can't be comfy here, but has been supervising most of the day:

Local conditions.