PSK

by Bill KB9SUP

I just thought I'd pass along some tips for setting up PSK cables, which I have managed to do successfully. I have had the grand total of 4 QSO's with PSK, and it's quite a thrill.

First, refer to the QST article in May, 1999 issue beginning on page 41. You can follow it pretty well but here is a bit of fleshing out:

1. When you download the software, it would be very helpful to set up a new directory, because you will get quite a bit of stuff in there very quickly; probably set up the directory, such as C:\PSK or such, first.

2. When you download, the web-site given in the QST article seems sluggish and failed to download properly. But at the top of the screen, it had a link to a second web-site which is more oriented to downloading. This one worked great.

3. When you download, you have several choices of versions. I picked one that sounded right to me. Unfortunately I didn't write down which one, and it may depend on your version of Windows. So good luck in this area.

4. After you download it, you will need PKZIP to de-compress it. I didn't happen to have a copy of PKZIP on that particular computer [I have several computers] so I searched the InterNet for PKZIP, easily finding the company's site and finding a free download option, which worked easily. So after PKZIP is installed, you can go back to the PSK file and double-click it, and it will de-compress very quickly, in a matter of seconds.

5. The receive cable is fairly simple. You need a Radio Shack style shielded audio cable, but a MONO cable, which has a one-eighth inch mono plug on one end, and on the other whatever you need to plug into your transceiver's external speaker output, or as the article suggests, perhaps an auxiliary audio line output. I used the external speaker connection and it works fine; you simply have to remember to keep the volume control always on the same setting [and you can check the "waterfall display" for signs of overloading, and use the Windows volume controls, as per the article.] My volume setting was the same as for normal speech, or a bit LOWER.

Speaking of volume controls, they didn't make this too clear. In my system, I right-click on a symbol near the clock at lower right of my screen [Windows 95 in my case] and then click on "Adjust Audio Properties." My receive audio is set on 5 of 10 for Recording [receive] and from 2 to 4 of 10 for Playback [transmit.] Depends on antennae I am using, and the band, and propogation conditions. But your sound board may be different.

6. The transmit cable will probably require some rather delicate soldering. I bought the Radio Shack parts [larger stores have them in stock.] Besides those listed, you may need two shielded MONO audio cables and [in my case, Kenwood] an 8-pin microphone jack. I went through the mic jack because my external auxiliary ports were inadequate. The circuit diagram is self-explanatory except:

a. you need MONO audio cables [on the sound board side, they plug into SPKR OUT; also a one-eighth inch plug.] b. the outer ring of the inputs and outputs means ground, I learned from Ed Tahl, local ham, which is the outer, braided strand. c. the transformer simply has 4 wires coming out of it; I used the blue and red to go to the POT, and the yellow and white to go to the MIC. If those colors don't work, you must make sure those on the POT side are on one side of the steel core of the transformer, and those on the MIC side, the other side of the steel core. d. Luckily, the Radio Shack MIC connector had numbers stamped by the pins, so along with my transceiver's manual, I was able to locate the MIC and the Grnd pins [diagrams in manual were almost impossible to interpret.]

Lo and behold, it worked! If I can do it, with my Boy Scouts level of electronics knowledge, you can do it! Let me know if you make it, or get stuck. If you want to do a 10 meter test, phone me in the early evening at 221-1601 and we'll do some tinkering.

Speaking of tinkering, my POT volume control is actually backwards, but it doesn't matter. Remember, you have to tinker with about 5 or 6 volume controls: the POT in the attenuation circuit, you Windows volume levels from the sound board, your MIC output control on your transceiver, your transceiver's POWER control, your AF control for receive only, plus your antennae tuner from time to time. My VOX was too sensitive, so I have to manually switch from Send to Receive. I was surprised that I need entirely different settings for the vertical vs the dipole, and for 10 m versus 20m, etc.

It's a lot of tinkering, but it's fun and FREE!!

Cheers, Bill KB9SUP

To join the PSK group, contact Stas KC2AK at staskc2ak@aol.com