eHam Forums => Digital => Topic started by: WB0DMA on October 04, 2004, 10:54:05 AM

Title: PC Interace Recomendations?
Post by: WB0DMA on October 04, 2004, 10:54:05 AM
What are your recommendations for a PC interface to run PSK13 and some of the other digital modes?  I would like to have rig control in the future as well. I have a 756 ProII.

Title: PC Interace Recomendations?
Post by: N0IU on October 04, 2004, 01:33:53 PM

Are you willing to build one? I have a 756Pro and built the one designed by Bob Lewis AA4PB. The article is in the March, 2002 edition of QST. At the time, Bob was selling beautiful silk screened through-plated printed circuit boards and had detailed instructions.

The only real down side to this project is that it cost me over $100.00 to build it. I could have purchased a factory built model for less money, but I am the kind of person who enjoys building and it is worth it for me to pay a little extra and know that I built it myself!

de Scott NØIU

Title: PC Interace Recomendations?
Post by: W4TME on October 04, 2004, 01:36:25 PM
I have tried a lot of them and I recommend two of them.  If you want to build your own interface, then the ProData Interface that was featured in QST March 2002 is just perfect for the Pro II.  It has two features other than a lot of isolation on the audio lines I really like.  First is the ability to key the rig using a SOX (sound operated switch) which doesn't tie up a comm port on the computer for rig keying.  The second is an ACC1 connector pass-thur feature that allows you to plug another device into it, such as a TNC or in my case a Heil Goldline Pro mic.  There is a front panel switch that allows you to select either the interface or the device you have plugged into the pass-thru.

For purchased interfaces, I highly recommend the SignaLink SP1+ (  It has all of the features above with the exception for the ACC1 pass-thru.  It is also 2/3 of the size.

You can get much cheaper interfaces, such as the Rascal, that if not DOA from Buck, work OK.  My feeling is if you have paid top $$ for a great rig such as the Pro II, you should spend a few extra $$ and get a digital interface to match.  I wouldn't put Wal-Mart tires on a Porsche. HI HI.

-Tim W4TME

Title: PC Interace Recomendations?
Post by: WB0DMA on October 05, 2004, 10:41:50 AM
Thanks for the feedback.  I am impressed by hams providing excellent feeback in these forums.

Title: PC Interace Recomendations?
Post by: KI6LO on October 06, 2004, 12:37:18 PM
".....I wouldn't put Wal-Mart tires on a Porsche. HI HI. "

Nothing wrong with Walmart tires providing the specs fit the usage. And besides who is going to be able to read the brand name at 100+mph. HIHI.


Title: PC Interace Recomendations?
Post by: KC0RDG on October 06, 2004, 02:47:14 PM
SignaLink is awesome!

Title: PC Interace Recomendations?
Post by: N4ZOU on October 06, 2004, 03:35:15 PM
Icom properly isolates the audio in and out on the acc connectors on the rear of their transceivers. My sound card interface is nothing more than two resistors which are 10K and 100 ohm for a 100:1 audio reduction so you can't overdrive the AFSK or microphone input on the transceiver. As for PTT you're PRO II has VOX so just use that. When you start feeding AFSK audio tones into the Microphone input on the front of the Pro II the VOX will trip (after you turn it on) and key the PTT. I prefer serial port PTT myself and use a 4N33 chip, a diode, and a resistor all contained in the serial port connector cover. There is no need to spend $100 for a simple audio interface. Again, with Icom transceivers no isolation transformers are required as the ports (front and rear) are already properly isolated.

Title: PC Interace Recomendations?
Post by: AA4PB on October 06, 2004, 06:52:22 PM
The ports (both mike and acc audio input/output) are NOT isolated on the Icom PRO or PRO-II transceivers. All the signal return paths are via the transceiver's common ground. Depending on your equipment setup, grounding, location of the antenna in reference to the shack, etc. you may indeed not require any isolation. On the other hand, if you have ground loop or RFI issues you certainly will require ground isolation of the audio signals. This is no different on the Icom PRO series than it is on most any other rig.

I too have run a number of rigs with nothing more than voltage divider resistors and had no problems. On the other hand, I've received reports that the RFI filters and isolation transformers in the ProData have cured RFI problems that existed with several simpler interfaces. As several pointed out, the down side is that all those components, the metal case, etc add up to about $100 plus your time to put it together. If cost is an issue then I'd recommend starting with the resistors and then check your signal on each band to see if it is clean and hum-free. If so then you saved yourself about $98.

Title: PC Interace Recomendations?
Post by: AA4PB on October 06, 2004, 07:07:29 PM
The PRO and PRO-II VOX does not function with audio signals applied via the ACC connector so it is necessary to use an external PTT of some sort if you wish to take advantage of the ACC connections. One advantage of the ACC connector over the mike connector is that you can simply switch to data mode which will disconnect the mike signal rather than disconnecting and connecting cables. With the PRO-II, using the data mode automatically disables the speach processor and gives you another set of three DSP filters on the receiver (allowing you to have three filters for SSB and three filters for data).

The SOX circuit in the ProData was designed with a decay time tailored to PSK31 to minimize the change over time back to receive and to minimize (not necessarily completely eliminate) the possibility of accidentally tripping it with other computer sounds.