KF0RT

[N3ATS]

Since you did such an elegant job at creating your interface you inspired me to build a new PSK31 interface.

I am not a component level dude. I suck at it, as a matter of fact! :lol:

So here is my design for my PSK31 interface using a compilation of designs I gleaned from the internet. It has pots to adjust audio in and out, and a LED for TX.

Let me know what you think, and if I did anything wrong. I am sure I did somewhere.


http://i81.photobucket.com/albums/j238/swweiss/schematic.jpg

http://i81.photobucket.com/albums/j238/swweiss/box.jpg

[N1LAF]

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http://paulfelgate.com/hamradio/serial/serialschematic.gif

Radio Interface Link Description, more info - Click here (http://paulfelgate.com/hamradio/serial/index.html)

Original Design
Works with desktop and laptop computers (with 5V serial)
Works well with ICOM Radios and the Kenwood TH-F6 Radio
Radio Connection diagrams
Theory of Operation, PTT Option on website

[kf0rt]

That looks about right, Steve. I'll have to check into what I'm using when I get back from work today, but the audio circuits are the same (from memory). I assume the 4N25 is an opto-isolator of some sort.

I think I just used a 2N2222 for the PTT.

Can you believe folks spend a couple hundred bucks on this stuff?

[N3ATS]

Thanks dude. I posted a revised schematic and how the box would look. Yes, 4N25 is an optocoupler.

[N2RJ]

That looks about right, Steve. I'll have to check into what I'm using when I get back from work today, but the audio circuits are the same (from memory). I assume the 4N25 is an opto-isolator of some sort.

I think I just used a 2N2222 for the PTT.

Can you believe folks spend a couple hundred bucks on this stuff?

Yes, I can.

However, I bought a RigExpert, which is much more than just a simple sound card interface.

It has a USB sound card built in, as well as virtual serial ports for FSK, CW, PTT and an extra serial port for the rotor.

Worth the money, IMO.

Certainly, I wouldn't buy just a sound card interface, but I want my sound card free for other stuff so I got a RigExpert.

[K8YS]

ok, I expect to be flamed by the inbred unwashed on this, but you DO NOT NEED Optoisolators and transformers.

YES! You DO NOT NEED THEM and you can still play PSK31.

Provided that you take BASIC precautions to keep RF out of the audio - ferrite beads, and a simple NPN, almost ANY NPN - should be a weak signal transistor, to key the line. I've used 2n2222's, MPSA12's, even MPSA13's.

The power supply should be common to all devices and I have connected a ground to the laptop.


I made up a cable that goes from the DB9 on the laptop to the 13pin mini DIN on the IC703, all od my connections are made in the DB9 shell as well as one NPN transistor, I also added a 330 Ohm 1/16W resistor onthe base of the transistor to limit the current to fire the tranisistor...

[N3ATS]

ok, I expect to be flamed by the inbred unwashed on this, but you DO NOT NEED Optoisolators and transformers.

HEY! I resemble that remark! :lol:

Do you have a schematic or a drawing of what you've done? I would be interested in seeing that.

I have a tendency for RF in my shack because of being on the 2nd floor and the close proximity to my antennas. Not only that, but I can help eliminate hum, 60 cycle, ground loops, etc. I am a clean signal nut when it comes to PSK.

I am currently using a Rascal interface but I wanted to make something of my own with exterior audio pots for in and outgoing audio. I figured it's going in a decent sized box, I may as well build it as robust as I can while not going overboard. I do like how both sides of everything are completed isolated.

I do want to see a pic or drawing of your thing though, sounds neat!

[K1OU]

'YS,

Go easy on the Bengals. I've been a pissed off fan for a long time. WHO DEY!!!!!!!!!!!


http://www.frontrowking.com/football/images/ChadJohnson01.jpg

[N3ATS]

Sheesh, look at the grille on that dude. :shock:

[kf0rt]

Steve-

Looking at the schematic I used (too lazy to draw it up)...

On the audio from the rig to the sound card, I just used the transformer, nothing else. Of course, that won't give you level adjust.

From the sound card to the rig, the circuit is pretty similar to yours except:

I have a 1200 ohm resistor in series with the transformer output (sound card side). And a .01uf cap across the input of the transformer, in parallel with the pot. Input isolation cap is .47 uf instead of 10uf and the pot is 1K.

Dunno if any of that makes much difference -- analog ain't my forte'. But, it works, and this is essentially the same thing as what's in the RASCAL.

And in reality, I've never tested the audio from the soundcard to the rig because I run FSK RTTY and don't need it.

[K8YS]

ok, I expect to be flamed by the inbred unwashed on this, but you DO NOT NEED Optoisolators and transformers.

HEY! I resemble that remark! :lol:

Do you have a schematic or a drawing of what you've done? I would be interested in seeing that.

I have a tendency for RF in my shack because of being on the 2nd floor and the close proximity to my antennas. Not only that, but I can help eliminate hum, 60 cycle, ground loops, etc. I am a clean signal nut when it comes to PSK.

I am currently using a Rascal interface but I wanted to make something of my own with exterior audio pots for in and outgoing audio. I figured it's going in a decent sized box, I may as well build it as robust as I can while not going overboard. I do like how both sides of everything are completed isolated.

I do want to see a pic or drawing of your thing though, sounds neat!



http://www.k8ys.us/interface.htm

[N3ATS]

Steve-

Looking at the schematic I used (too lazy to draw it up)...

On the audio from the rig to the sound card, I just used the transformer, nothing else. Of course, that won't give you level adjust.

From the sound card to the rig, the circuit is pretty similar to yours except:

I have a 1200 ohm resistor in series with the transformer output (sound card side). And a .01uf cap across the input of the transformer, in parallel with the pot. Input isolation cap is .47 uf instead of 10uf and the pot is 1K.

Dunno if any of that makes much difference -- analog ain't my forte'. But, it works, and this is essentially the same thing as what's in the RASCAL.

And in reality, I've never tested the audio from the soundcard to the rig because I run FSK RTTY and don't need it.

Thanks! Once I get it built, and if it doesn't work to my liking, I will fiddle with the different values you mentioned.

[kf0rt]

Bob's one-transistor PTT interface is real typical of what I've seen and it works very well. This is the same as what you'd use to key CW from a computer (but don't use it to key a tube rig).

One of the problems I had with my switch box was getting the PTT to work with my Drake T-4XC. It turns out that the PTT line in that rig is very high impedence -- you can actually put it in transmit mode by touching your finger between PTT and ground. For this, I ended up using a grid-block keying circuit, just like what I used for the CW interface.

All this solid state stuff sure makes interfacing easy.

[N1LAF]

Bob's one-transistor PTT interface is real typical of what I've seen and it works very well. This is the same as what you'd use to key CW from a computer (but don't use it to key a tube rig).

One of the problems I had with my switch box was getting the PTT to work with my Drake T-4XC. It turns out that the PTT line in that rig is very high impedence -- you can actually put it in transmit mode by touching your finger between PTT and ground. For this, I ended up using a grid-block keying circuit, just like what I used for the CW interface.

All this solid state stuff sure makes interfacing easy.

Would a MOSFET work here?

[kf0rt]

Bob's one-transistor PTT interface is real typical of what I've seen and it works very well. This is the same as what you'd use to key CW from a computer (but don't use it to key a tube rig).

One of the problems I had with my switch box was getting the PTT to work with my Drake T-4XC. It turns out that the PTT line in that rig is very high impedence -- you can actually put it in transmit mode by touching your finger between PTT and ground. For this, I ended up using a grid-block keying circuit, just like what I used for the CW interface.

All this solid state stuff sure makes interfacing easy.

Would a MOSFET work here?

A MOSFET would probably be ideal, but it turns out there's no need for anything too special. As I recall, the PTT line impedence on the Drake is about 10 meg -- you can easily key the transmitter with a 1 meg resistor to ground.

Here's the circuit I used (works fine for both CW keying and PTT):

http://home.att.net/~jacksonharbor/gridbsch.pdf