HAM Radio Page

Our conception of QRP

I am HAM since 1981. Because of financial difficulties I got my home station when I made my homebrew QRP. With no measuring equipment that required much of hard work.

With my friend Sasa Cokic YZ1SC, I started to build all the instruments. We have had only the multimeter and then we made the dip-meter, HF sonde, frequency counter, but the most useful device was the instrument for resonant circuits frequency measurement (specially designed oscillator that work as attachment to frequency counter). With the noted instruments we then could easily adjust all the coils and the bandfilters, and build "very complex" radio receivers and transmitters.

My first QRP station (and Sasa's too) was single super with one stage HF amplifier and MOS-FET mixer on the Rx side and then IF amplifier (IF is 8001.43kHz, that is the frequency for which I found quartz crystals) with the home made XF with very weak pass band. The product detector and AF amplifier was TCA440. The Tx side started with the xtal oscillator on 8001.43kHz, that is then mixed with the main VFO signal in the DBM with two bipolar transistors, and then amplified to 1W output power in C-class. The VFO was carefully designed with FET-s and bipolar transistors, and carefully temperature insulated and stabilized with several capacitors. It works on aprox. 6000 to 6350kHz to cover the 20m band. It works only CW.

We tested several antennas, but best results give the fixed wire HB9CW beam even on my very bad location and in my very small garden with very much telephone wires (of course we had no money to try real rotary beams).

Then followed the very serious project - the tube power amplifier. It is with the TV tubes (two-PL504) and the power is about 100Watts.

Now I have worked about 160 countries but less than 100 on QRPP (with my 1W). Unfortunately not all confirmed.

Literature

The best source about HAM radio technique was the Bozo Metzger's book "The Handbook for HAM's and Technicians" (in Serbo-Croatian language).

The ARRL Handbook we got in 1995. (Only xeroxed parts of the 1990's edition). If someone has some newer edition and doesn't need it, the gift is welcome (It's not more necessary, because I've got my the first own example of ARRL Handbook 2000 and I'm very, very, happy because of that).

The Rothamel's "Antennas" (the Serbian translation) is very good book about the antenna theory and practice. The ARRL Antennabook we have not seen, yet. The gift is very, very welcome.

In free hours we constructed the VHF FM transceivers for local work only. We are not too interested in DX-ing on VHF.

Our new project is multi band HF transceiver. We studied in details the FT757GX conception and decided to do something similar (of course a little simplified). The microcontroller synthesizer will cover all bands. In it will unfortunately be only one crystal filter because it is very expensive to us (some people place several pieces, I have no place to stole it!)

We'll see the results...