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From n3kl.org

 

Would you like to work Oceania, pacific or some other DX with 20W? If you do then you should start working digimodes. I will try to explain it here in basic, so you could start working quickly.

What do you need? You need transceiver, computer (at least 486) and software for digimodes. When you get all this, you should first connect your computer and transceiver. Most digimode softwares are made for sound card, so your PC should have one. There are few possibilities how to key your transceiver via sound card. You can key it by using VOX from your transceiver, key it manually or by using a little interface. I will explain here how to make a little interface.

HARDWARE

INTERFACE:

It's very simple to make it. You need:

  • shielded cable

  • female COM PORT connector with case

  • MIC connector that fits your station

  • NPN transistor (BC107, BC109....) & resistor 10kΩ

    That's all regarding hardware for your transmission. Now you need to make another cable for receive. One end of cable connect to your external speaker or headphones jack of your transceiver. On second end of cable you should solder banana connector that fits to your PC sound card (line in or mic jack). When you finish this cable, just connect PC&radio and your job with hardware is finished. Click
    here to see schematics of interface.

    SOFTWARE

    Now you need software to work digimodes. There's a lot of digimode softwares. Some of them are made only for one type of digimode (i.e. Digipan (PSK), MMSSTV (SSTV), MMTTY (RTTY), PSK deluxe,...) and some of them unite all types (PSK, SSTV, RTTY, packet,...). Those programs are demo versions or shareware. Press here to find links to this programs. After downloading and installing software to your PC, you should do the following things:
     

  • Enter your personal data, like your call, name, QTH and if you know, your grid locator. That's important for macros (see below), because you put CALL, NAME or QTH command instead writing it each time.

  • Configure PTT or CAT control. You must do this if you wish to transmit.

  • Adjust output and input volume control. Important thing in digimodes is that you use low power, not more than 50W. Why, you will ask? Because for receiving quality signals, it's not needed to hear it loud. The best is if your signal is between -25 and -30dB (IMD measurement). With strong signal you will disturb and not allow others to receive, because your signal will be wide, overridden and covering low signals. You can increase/decrease power with output volume sliders or with MIC gain. For the first time put your sliders a little bit below 50% ( volume&wave) and experiment with sliders and MIC gain, until you reach power about 50W max. The best is, if you do it with dummy load, so you will eliminate QRM and your radio will not sweat. Do not transmit for long time while setting output volume as it may break your radio!! The same rule is also for input volume. It will be OK if you put sliders to minimum ( turn off MIC booster). If nothing is received, then push slider bit by bit higher, until your receiving of signal is readable. Remember that you can destroy your sound card if strong signal gets into it, so watch out what you're doing!! Also adjust volume on your radio, don't turn it too loud. It won't be bad if you read help file of program you will be using.

  • Write macros. Macros are "buttons" in which you write informations that you will transmit (i.e. your name, QTH, grid locator, working conditions,...). They allow you to transmit all this data with a simple mouse click or by pressing function key, instead of typing it every time. You write data into macro when you right click on macro, macro window opens, and then you write data. Usually you should first put TX command, then write data and at the end put RX command. Look well description of commands in command window as they might make it easier for you to write macros.
    Almost every digimode program has it's own
    log, so you needn't to write extra log for digimode QSO's.

    Now regarding frequencies for digimodes on 11m, they are not defined. Most operators in Europe use following frequencies:

    27.500MHz - RTTY, PSK, CW (if you are familiar with this kind of transmission, 
                           you can work here without digi software)

    27.700MHz - SSTV call and then QSY

    27.900MHz
    - packet

    This would be the basic things about digimodes. For better understanding you should carefully read help menu in your digimode software. If there are any questions about this matter, you can write me and I'll try to answer them.


    There are not many people working digimodes on 11m, but YOU can help us by your presence to attract people working this kind of transmissions. Looking forward seeing you on my screen.