Started in 1971 as DU1AFS in Manila with a homebrew 120-watt CW and AM transmitter using a pair of 6L6GC finals to work 40M and 20M. Receiver was an Ecophone EC-1A with an outboard preselector then later changed to a Hallicrafters SX42. I enjoyed so much dx with this setup. I built another homebrew transmitter to operate on SSB with a pair of 6KD6 sweep tubes for more PEP power. This inspired me to finish an Electrical Engineering degree from University of the Philippines. In the 80's I worked in the broadcast industry then moved to the vhf/uhf radio business making repeaters and setting them up for civilian and goverment agencies. In the 90's I moved into designing circuits for commercial electronics and cellular. After more than 40 yrs in Electronics, I like restoring and operating old (and obsolete!) radios.
Homebrew all-mode HF transmitter with a pair of 6KD6 sweep tube finals (above) from 1974.
Whenever I go on the air with my KWS-1, it likes to drift a few hundred hz over 2 or 3 hours. This was state of the art in 1956 but nowadays people get very concerned when they hear someone drift that much! Since I use the KWS-1 regularly, I decided to upgrade its frequency stability to be at least equal to modern rigs. I designed a homebrew DDS frequency control board (above) for the KWS-1 using an AD9851 chip with OCXO reference. The KWS-1 still works just like before and the DDS circuit is completely undetectable. However the OCXO now makes the 1956 transmitter extremely stable (0.1ppm) and once again a pleasure to use in todays ham bands.
Last modified: 2013-03-07 06:37:49, 1933 bytes
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