Not sure if this is the right place for this.. Baffled on IC-745 PSK hookup issue...

[N1RKR]

I have recently started tinkering with PSK31 on 20m... My HF rig is an IC-745, which is an older radio, but perfectly capable... I've been trying to get my radio hooked to my PC in a way that's semi-permanent, and in such a way that I don't have to actually HEAR the PSK sounds. Here's what I have so far...

The radio has a 24 pin accessory port on the back. Reading the pinout, it seems that ground, audio out, and audio in are all available. I confirmed that this *should* work as expected when reading up on the Signalink USB unit. I can purchase a Signalink USB with an unterminated cable, and a blank 24 pin plug, and Tigertronics gives me the pinout. Now the signalink USB unit is nothing but a sound card, and a switch to key the transmitter. For the $10 worth of parts needed to create it, I get to pay $120! So I'm trying something else first. Plus, isn't ham radio a hobby for do-it-yourselfers?

So here's what I've got so far. The audio out works just fine. I can get the sound from the radio to the computer just fine. My waterfall works exactly how it's supposed, and all is well there. So, that's part of the battle.

However, audio coming out of the computer doesn't seem to make it into the radio. I've wired pin 5 on the accessory plug to the left channel audio out on my computer. This works just fine plugging the wire into a standalone speaker (where I've confirmed that the PSK sounds ARE coming out of the left channel of the wire), but when I hook it to the radio, nothing. It's like it's not even connected. Even when I manually key the radio, it acts like it's not getting any audio from the computer, and I know that it should be. It's the most baffling thing. The Signalink USB schematics tell me to use that pin for their product, so it should work in my configuration as well, but it does not.

And, without being able to use the direct audio connection, I've been hooking the audio out to a speaker, which I place next to the microphone, and turn on the VOX control. As soon as I tell FLDIGI to start transmitting, it sends the screeching sound to the speaker, which the mic picks up, which kicks in the VOX, which works just fine... Except that I have to listen to the screeching.

Logic states that if I can figure out the audio from the PC to the radio problem, that the VOX should also take care of my keying as well. But I'm completely baffled why that doesn't work...

To clarify, right now I have two 1/8 stereo jacks wired to the 24 pin connector that's plugged into the back of my radio. The ground wire from both of the jacks are wired to pin 8 (Ground) of the accessory plug. The left channel wire of the jack for audio out of the radio is wired to pin 4 (Fixed level audio out). The left channel wire of the jack for audio into the radio is wired to pin 5 (Transmitter MIC amp stage). I use two 1/8 to 1/8 wires to connect the jacks on my little wiring harness to the jacks on my sound card. With the exception of the Signalink that also has a connection to pin 3 for PTT, my wiring is identical. Yet it does not work.

Has anyone ever successfully used the 24 pin accessory jack to wire to a PC? Am I missing something? I really don't want to spend the money for a Signalink USB if I don't have to, but I'm so frustrated at this point I'm actually considering it... Please help!

 

[N1RKR]

Here is a diagram from Tigertronics for the pinout of my 24 pin accessory port on my IC-745.

For what I'm doing, I don't need the 13.8v out, nor do I need the PTT (or if I do, I'm not concerned with that YET). And my audio out, mic in, and ground are wired like they say...



Afternote: Just to make sure, I hooked up pin 3 to a wire, which when grounded, causes the radio to go into transmit mode. Just in case the radio was looking for the PTT to come from the rear plug before accepting audio in from the rear plug, I hooked it up and used that lead to key the radio, and that made no difference...

So, it seems everything is working just fine, except that the audio coming from my PC isn't actually getting INTO the radio, or the radio isn't registering it... Arrgh, I'm soooooooo close, and yet so far...

 

[N1RKR]

Update: After more tinkering...

So, as I said before, I wired the 3 relevant pins on the accessory plug for my radio to two 1/8" jacks. One for audio out of the radio, and one for audio back into the radio.

The audio out port has been working like a champ.

The other port has not done anything useful up to this point.

However, I decided to test a theory. I plugged a regular computer microphone into the 1/8 jack for the audio input into the radio. The audio level that got into the radio was ridiculously low, like barely audible, but it was enough to move the rf meter on the radio, and if I cranked up the level, it was also enough to trigger the VOX on the radio when I turned it on.

So, here's where I'm at...

I have a 1/8 to 1/8 cable connected to my computer's speaker jack. I have confirmed that the audio coming out of FLDIGI is going through that cable, as I can plug the other end of that 1/8 cable into the input of a powered external speaker, and I can hear the audio.

I have confirmed that the wire that I put on pin 5 (and the ground on pin 8) of the accessory jack is connected properly, and that the 1/8 jack on the other end of that harness is correct. Since I plugged in a microphone, and audio was getting into the radio, this confirms that the connection from the 1/8 jack I put on the end of the harness, and the wiring and connections to the accessory jack on the back of my radio is correct.

Essentially, I've tested separately the entire path between the computer's output and the radio's input, and each of the two parts work individually, however, when I hook them all together, no audio gets into the radio.

I have even confirmed my theory (that as of 10 minutes ago I assumed logically it would work, but didn't actually know) that audio coming in from the accessory port WILL trigger the VOX on the radio if it's turned on, so that takes care of that concern.

At this point, the only thing that's holding me up is the audio from the computer to the radio. There's GOT TO BE something stupid I'm just not seeing here.

I'm out of ideas. PLEASE HELP!

 

[N1RKR]

Good news and bad news...

Well, good news is that I have it working the way I want it.

Constant level audio coming out of the radio into my PC. Audio out of my PC going into the radio at a proper level. And VOX taking care of keying up the radio when necessary...

The bad news is that I can't do it the way I wanted to do it. It looks like it's going to require the use of both the Accessory Plug on the back as well as the MIC connector on the front. Ugh...

The constant level audio is coming from the Accessory port. Though the wiring for my radio says that pin 8 on the mic connector should be an audio output, I don't appear to be getting any. Or if I am, it's controlled by the AF gain, which doesn't work for me, so audio from the radio to the PC must come from the accessory port on the back.

Through trial and error, it turns out that there WAS audio from my PC getting into the radio through the accessory port, however, it was at such a low level that it was useless on SSB. Interestingly enough, it seemed to be ok when transmitting on FM *shrug*... But it wasn't enough to create a "carrier" on SSB, and wasn't enough to trigger the VOX. I'm guessing it's a pre-mic-gain input and is not affected by the mic gain knob. Interestingly enough, if I cranked it up full blast (both the volume output and the vox gain), it did (sorta) click the transmitter over and over, but wouldn't hold the transmit...

So, audio from my PC must go in through pin 1 on the mic connector on the front of the radio. Initially, this worked getting audio into the radio, but I had the PC volume set to 1%, and the mic gain all the way up. This technically worked, and when I transmitted using FLDIGI, it would key the vox, and the audio level appeared to be fine in that the ALC did not kick in at all, but when listening to what was actually getting transmitted (using another radio), there was a kind-of ticking coming through with the PSK signal... I was alerted to something being off when I tried to initiate PSK contacts with people I should have been able to talk to just fine, but all came back QRZ? QRZ?

More trial and error resolved that... I have now set the PC's volume control to half-way (50%), and set the mic gain WAAAAAAAY down (like 8:30 position - 1.5 out of 10). I have made two quick contacts and all appears well. I specifically asked those two contacts how I looked on their waterfall (trying to make sure I wasn't overdriving or splashing all around), and both said that I was 100% and clean signal.

At the moment I'm connected to the mic connector using a test lead, as I don't have any extra 8 pin round connectors around at the moment. But I have one on order and it should be here on Tuesday...

But I have confirmed that it works, and I no longer have to listen to the squealing of PSK when I transmit. I also don't have to adjust the volume every time I change where on the waterfall I'm transmitting (speakers and mics pick up some frequencies better than others, so when I was high on the waterfall, I had to turn the volume down, and when I was low on the waterfall, I had to turn it up to keep my power output where I want it)...

I hope my posts (and my solution) helps someone else who wishes to hook this radio up for PSK.

-Eric

 

[Moleculo]

Man, that sounds like quite a trial and error process to get that figured out. I'm glad you did and thanks for sharing. I'm sure your experience will help others, as well.

 

[Road Squawker]

... It looks like it's going to require the use of both the Accessory Plug on the back as well as the MIC connector on the front. Ugh...

The constant level audio is coming from the Accessory port. Though the wiring for my radio says that pin 8 on the mic connector should be an audio output, I don't appear to be getting any... audio from the radio to the PC must come from the accessory port on the back...

Gee, something doesn't sound right,......... why does a Mic have an audio OUTPUT to the computer?

the sound card input should come from the ACC port or the headphone jack.

 

[N1RKR]

Actually, in researching hooking up a radio for digital work, particularly when researching the Signalink USB device, it seems that though it had rarely (if ever) been used in the past, many radios have an audio output in the mic jack. I guess it's one of those "just in case" things that they've always done. Look up the wiring diagram for the mic on your radio, I am pretty sure yours probably has one too...

 

[Road Squawker]

... the wiring for my radio says that pin 8 on the mic connector should be an audio output, I don't appear to be getting any...
so audio from the radio to the PC must come from the accessory port on the back.

... many radios have an audio output in the mic jack.... Look up the wiring diagram for the mic on your radio, I am pretty sure yours probably has one too...

err, no,... they have a RADIO audio INPUT
you are trying to get audio into the PC,... NOT the radio.

you don't seem to understand the mic's pin 8 OUTPUT is the radios INPUT.

all I can say is you turned a simple task into Rube Goldberg contraption

 

[Captain Kilowatt]

Gee, something doesn't sound right,......... why does a Mic have an audio OUTPUT to the computer?

the sound card input should come from the ACC port or the headphone jack.

err, no,... they have a RADIO audio INPUT
you are trying to get audio into the PC,... NOT the radio.

you don't seem to understand the mic's pin 8 OUTPUT is the radios INPUT.

all I can say is you turned a simple task into Rube Goldberg contraption

No bud, YOU do not seem to understand what is REALLY going on. No Rube Goldberg contraption happening at all here.Most amateur radios do in fact provide an audio OUTPUT on the MICROPHONE connector. It is most often used when using a headset with a microphone built in. Nothing unusual with audio OUT appearing on a MIC input connector. As long ago as when the Icom IC-735 came out Icom was using pin #8 for audio output for headphone use. I know, I had one and used a headset mic with it.below is a typical Icom microphone connector. You can see pin 8 is indeed audio OUT while pin 1 is the microphone audio INTO the radio.

 

[N1RKR]

err, no,... they have a RADIO audio INPUT
you are trying to get audio into the PC,... NOT the radio.

you don't seem to understand the mic's pin 8 OUTPUT is the radios INPUT.

all I can say is you turned a simple task into Rube Goldberg contraption

When reading a microphone connector pinout, the term AF Output is pretty straightforward. You don't understand that an AF Output is just what it says, an Audio OUTPUT, meaning it should be audio out of the radio into my PC. But it turns out that that output that's part of the microphone connector appears to be controlled by the AF Gain (Volume Control) on my radio's face, which is not what I wanted when doing PSK work. I wanted a constant level output regardless of what my AF Gain (Volume Control) knob is set at. To get that I needed to go thtough the accessory port on the back, as that's the only constant level audio output my radio provides.

I'm not sure what a Rube Goldberg contraption is, but my harness is very simple. Audio from the radio into the pc comes from the accessory port on the back of the radio, and audio from the pc into the radio goes through the mic connector on the front of the radio.

 

[N1RKR]

I also want to point out here that I'm new to HF work, and digital work, and really hooking up a radio to my PC at all. Information on the Internet on this is sketchy, as everyone defaults to "buy a signalink" or "buy a rigblaster". I didn't want to go that route.

Also keep in mind that when this radio was built (mid 80s), a computer was considered just a fad, so clearly the documentation didn't have computers in mind when it was written. And most people who post stuff on the internet about connecting radios to computers are connecting new(er) radios, ones with DIN connectors and/or USB ports built right into them. Those that don't tend to fall back on the Signalink or Rigblaster, so essentially I did this all from scratch.

And while I could have posted just the end results here, I decided to post as I did my trial and error, so that others with older radios, who may run into a similar or the same issue as I do, can search for their issue and see this thread, and follow logically how I worked through my issues, so hopefully it will help them work through theirs. This is especially true now that my issues are resolved and it's working.

I hope this thread helps someone else. Isn't that what the forums are ultimately for?

-ET

 

[Captain Kilowatt]

I used to use an IC-735 and IIRC it had two accessory jacks on the back. I was able to get audio out as well as put audio directly into the modulator stage via the rear panel jacks. No messing with the mic connector on the front at all. You should be able to do the same thing and leave the mic jack untouched.The af out on the mic jack is indeed adjustable with the volume control as it was intended to feed a headset.

 

[N1RKR]

I used to use an IC-735 and IIRC it had two accessory jacks on the back. I was able to get audio out as well as put audio directly into the modulator stage via the rear panel jacks. No messing with the mic connector on the front at all. You should be able to do the same thing and leave the mic jack untouched.The af out on the mic jack is indeed adjustable with the volume control as it was intended to feed a headset.

I tried that at first. If you read my first post, and my first follow-up... I had connected the audio from the PC to what was supposed to be the audio input pin on the accessory port on my IC-745, but the audio level (even if I turned everything up) was so low it was unusable. I think that the radio expected some sort of amplified signal into that pin on the accessory port, but nowadays, computer sound cards are line-level outputs. There just wasn't enough oomph behind the sound signal out of the PC into that pin on the jack to be usable.

I'm sure if I had hooked my mp3 player up to that pin on the accessory port, it would have worked just fine, since my mp3 player's headphone jack is an amplified output.

Whereas the mic connector's input on the front is amplified inside the radio using the Mic Gain knob on the radio's face. Meaning I can turn the computer down to 35-50% output level, and use the mic gain to get the proper level without having to overdrive it.

 

[Mudfoot]

I enjoyed reading your post. I have also saved it for future reference for myself or one of my buddies. I learned a little as well. You seem to be a stickler for detail and I like that.

 

[N1RKR]

I enjoyed reading your post. I have also saved it for future reference for myself or one of my buddies. I learned a little as well. You seem to be a stickler for detail and I like that.

LOL. Sometimes I go overboard on the details, but only because I've been frustrated so many times with people who just gloss over a solution. They post a question, and then a month later post a reply saying "I got it working, thanks..." and nothing else.

While I started this post trying to get ideas on how to resolve my problem for me, as I tried things that either worked or didn't work, I decided to post as I made progress (or set back) in case someone else runs into a similar problem.

This is an old radio, and information on how to hook it to a PC was scarce at best. Most people just said to buy a signalink or a rigblaster, both of which are basically $5 sound cards, in a $10 case, with a $100+ pricetag. Nope, can't justify it if there's another solution, thanks...

I had a thought of how it could work without buying one of those expensive signalink boxes, and though it was frustrating, I did manage to get it working exactly how I wanted it to work. I had hoped to do it all through the port on the back so I wouldn't have to disconnect and swap mic cables, but such is life. It works perfectly, and I use it quite heavily, so it's definitely been put through it's paces. PSK31, PSK63, PSK125, PSK125rc4, JT65A, FeldHell, MT63... I can even record SSB signals coming in... It definitely works...