JUMA-TX1 Assembly Begins

20130113-144607.jpgThe green circuit board seen here is the first of three major assemblies, the DDS (Direct Digital Synthesis) board on which the transmit signal will be generated. Shown also are the tools and especially the large magnifier in the upper-right that contains a bright Circline lamp. All work will be done looking through that. (The hand-held magnifier is used only occasionally when double-checking something.)

The several pink and clear baggies hold the several dozen parts. If you click on the image for a bigger version, look in the lower pink baggie in its lower left corner. You may be able to see a tiny black square. That’s an integrated circuit with 10 separate connections, each of which must be carefully soldered to the circuit board, and without “bridging” any of the pins to another.

Here’s a close-up.20130113-150711.jpg

It is meticulous and exacting work.

A second PC board, to be assembled next, houses the power amplifier that boosts the RF signal on 40 or 80 meters to 5 watts, less than that of an old style night light. Coupled to an outside antenna that, ideally, is longer than the diagonal across the city-size lot on which our house sits, on a very good day, I can “talk” to other ham radio operators around the world. (On a bad day, I’ll be lucky to raise a neighbor half a mile from here.)

The third assembly will be the box that houses everything including switches and other controls to be manipulated by the operator (me). Finished, the unit is about 4x2x1.5 inches. The rig transmits only CW signals (Morse code) so, when not busy with the soldering iron and big magnifying glass, I’ll be practicing and getting my speed up to a reasonable speed again. 10 WPM would be a nice start but, to be practical, 20+ is the real goal. I could do 15 many years ago. Getting to there and then pushing on to 20 will take some time.

It begins.

2 thoughts on “JUMA-TX1 Assembly Begins

  1. Hi there Ed,

    A newby on the arduino forum (with the unfortunate name of “axman” :-) ) mentioned that you had provided him with a simple example Arduino sketch driving a Si570 DDS chip via I2C from an arduino.

    (the form post is at http://forum.arduino.cc//index.php?PHPSESSID=0ut665ntr702ktga8diep40887&topic=102906.0)

    I googled your call sign, and it led me to this site.

    If you do have such an arduino sketch, and you are willing to share it/them, I would be very grateful if you could email me these same sketch(es) (arduino programs) to drive the Si570 chip. My reasons are below.

    BTW, I have partly finished a “SoftRock” SDR transceiver (and with some struggle got it’s ATtiny driven Si570 LO to work !) . Being more comfortable with the open source and flexible arduino IDE, thought I would create my own LO and drivers using an Si570 driven with an Arduino UNO (AT328). I’d be happy to share whatever I create.

    Thanks in advance,

    Tom Low
    Sebastopol CA [Email address deleted]

  2. (sent by email.)

    Hi Tom,
    I’m afraid “AxMan” is incorrect. Sorry. I don’t have such a driver and have not sent him one. He must have me confused with someone else.
    Best wishes on your search!

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