Ok, So I am finally getting my IC-718 on the air with WSJT-X... I actually bought it from a member here; sorry, it's been forever. It came with a homebrew interface that connects to the 12 pin DIN on the back, goes through a level converter and audio transformers, and goes into a USB soundcard and COM port. Now, I don't know if this is just a serial PTT or full fledged CAT. I don't get any data on the screen, I just tries transmitting every few seconds and then locks on, and that's with VOX PTT, so I don't think it should be doing that...

Help? Am I SOL? I don't know what the heck I'm doing with this... which of course means the info I can find online is meaningless, because HAMs suck at making anything easy to get into.

Going to be hard to figure that out without detailed info on how the interface is supposed to work.

Did I sell it to you several years ago?  I seem to recall selling my IC718 to an Arfcommer.

IIRC, if the transmit power setting is too high it can muck things up.

It might have been! I'd have to go through my IM's. I'll try lowering the power and see if that helps.

Here is the CAT cable for the 718.
https://www.amazon.com/gp/product/B004L0T4UM

I can check my settings in a little while but I don't think it uses VOX.

That's not the cable in question.

There SHOULD be a business card in the package somewhere from the people that made the cable. They are NOT a ham radio place, but a sideline of something else like maybe flowers or some such shit.

The card should have contact information on it.

@Jupiter7200  get in here.

OP, post a picture of said unit and someone here will likely fix you up.

It's a homemade cable. Looks like an HE3621A0500 relay and a diode are all the control logic on there, so I doubt it's a CAT interface.

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It might be easier to just get a SignaLink

Thays what I used with my 817

Looks to me like what you have doesn't do CAT control at all.  I'd say it's just an audio isolator with a keying interface.  My guess would be to try the "PTT with RTS pin" or whatever the closest option is.  You should still be able to WSJT-X with that just with out rig frequency control.

Referring to the Amazon link, no, that is not what you need for digital with the Icom 718.  CAT control is not
what you need.

Looking at the photos of the homebrew interface, there are the old fashioned 600-ohm audio transformers,
one going, one coming, and a volume pot for transmit level...  all good.  This is just like many of the homebrew
digital interfaces that we used to make years ago.  On the air with hams from other countries, particularly those
from Cuba, Central and South America, they are amazed that we spend so much money on Signalink and other
such interfaces, when a simple one like shown in these photos is so easy and cheap to make.  

Tony's pictured interface is not unlike the one sold years ago by Donner, the Donner Digital Interface, which was
quite good.  There was also one sold on eBay, the Easy-Digi, either built or a kit, for about $12 or so for the kit.  
It used an opti-coupler instead of physical relay like the Donner.  

Tony, get that one working for you, it is all you need for any of the modes.

(Go to eBay, enter in search "Easy Digi".)

A tip, set your radio power to full 100 watts, mode to Upper Sideband.  In your digital program, set the audio slider
for transmit to 50%.  This gives you room to increase or decrease power, but 50% should always be a good setting.

Turn the little pot in the interface all the way down so that there is no power output as read on the external power
meter.  Transmit digitally, a CQ macro is good for this, and slowly turn the pot up until you have indicated... on a
separate SWR/Power meter... about 20 watts... and certainly no more than 25 watts.  There, leave it alone now, and
put the cover back on.

~ Jup

This is the Easy Digi kit:

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Easy Digi schematic:

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Donner Digital Interface schematic.  This may help you connect your interface.  Connection is the same
for the IC-718, IC-7200, and several other Icom radios.

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I connect my digital interface to the computer through a separate soundcard.  Those little cheap $2-$3
USB plug in soundcard interfaces do just fine.

Hey, check this out!

This is a description of Professor Arnie Coro's (CO2KK) digital interface.  Arnie is host of Radio Havana's
"DX'ers Unlimited" radio show.  He has several very interesting articles on the web about indoor SWL antennas
and other SWL related subjects.  More recently, Arnie coordinated relief into Haiti following their devastating
earthquake.

I asked Arnie to do a write up of his very simple digital interface described to me during a PSK31 contact.  The
following is edited from two emails.

"OH Yes amigo !

"It is very easy to assemble, and several Cuban radio amateurs use it with excellent results.

"Here is the full description:

"For receiving.... the signal from the transceiver's audio output is connected to a small loudspeaker that fits inside
a length of PVC pipe of about 5 inches, that is filled with sound absorbing material... at the other end there is a
small microphone that picks up that acoustic wave and is connected to the microphone input of the computer's
sound card.

"You have two places where to regulate the input to the sound card... at the transceiver volume control , and at the
computer audio control program sound level setting.  That is the RECEIVING path.  FULLY AND TOTALLY ISOLATES
THE TRANSCEIVER AND THE COMPUTER !!!!

"For transmitting.... what we have been doing lately is to fit a small microphone inside one of the computer's loudspeaker....
and that microphone output is connected to the transceiver's microphone input JACK.

"We have also taken the sound card output signal directly to the microphone input by means of a 600 to 600 ohms
transformer... but I prefer to use the ¨acoustic coupling method ¨ because the acoustic coupler avoids the possibility of
having ground loops and the certainly dangerous RF feedback that can be damaging to the computer, as some people
have found out the hard way!!!

"Here is the reply to your question about how the HF transceiver is turned on to transmit with my SIMPLE DIGITAL
MODES INTERFACE ...

"I simply do a careful setup of the rig's VOX, so that it will turn ON and OFF the transceiver.

"For my FM rig , when I want to transmit the satellite photos during the hurricane season, my only choice is to turn
on the transmit by pressing the PTT button using a footswitch.  The reason why I do it this way is to keep the TOTAL
ISOLATION, between the computer and the transceivers.  In other words, if you add a circuit that receives the signal
from a serial port to activate the transmission, this will require a physical connection with a cable (and of course a
single transistor or better yet an optocoupler ) that links the computer with the radio.

"A local friend uses what he describes as a much more perfect protection by employing an optocoupler device
(supposedly 5000 volts isolation ) that feeds a mechanical relay.... and then the wires that go to the rig's PTT are only
connected to the contacts of the relay. I had to agree with him that it was a very clever approach... and that it indeed
provides an almost perfect isolation... BUT, it your HF transceiver has VOX, then IMHO, that is the way to go!!!

"I use FLDIGI as my digital modes software, running on a LINUX box that runs PUPPY LINUX 5.2.8 , a very rugged
and small operating system that is easy to install and runs very well in old machines with little RAM available !!!

"73 and DX
Your friend in Havana
Arnie
CO2KK"