60's: The very first circuit that Hamtel has successfully built and tested was AM middle wave transmitter. It happened in mid sixties of the 20th century, in a fast growing city of Tuzla, in a peaceful valley among Bosnian mountains. The main designer was 6 years old. The device has been lost long time ago, but it is known that it was made with one germanium transistor AC550, some strangely shaped Russian resistors and capacitors, a piece of ferrite stick and coal type telephone microphone. Best DX was about 20 meters (Hamtel research lab was located at 7th floor, and signal was successfully received at 3rd floor of the same building). Of course that Hamtel radio labs was not known by that name then, the name changed with passing years very often, as well as location.

70's: Anyway, some new, more sophisticated projects followed. Headphone stereo amplifier, mosquito-repellent-audio oscillator, a lot of small audio devices used mostly for educational purposes, and finally, ten years later, the first ham radio receiver. Bingo. Regenerative receiver with only one Si-transistor. And the first real antenna as well - about 20 meters long piece of wire. This receiver was used extensively, mostly for monitoring local SSB QSOs at 80 meters band. And it worked fine. Even better after some modifications. And more modifications. This modification attitude was adopted as standard operating procedure for Hamtel labs later on. The first commercial project followed - thyristor based light show device.
In late seventies another field was discovered. It was 2 meters band. What a difference. VHF contests - portable operation at the dawn of SSB era on VHF. (Mostly) linear amplifiers with QQE06/40. Preamplifiers with ultra-modern BFT66, and BF981. High speed CW MS QSO's. Memory keyer with more than 10 TTL circuits, completely made in ugly construction technique. 4CX350 linear amplifier and GaAs FET preamplifiers.
Another commercial project - no name QRP transceiver for 80 meters band.

80's: Next decade most of the time the key personnel (me) spend at electrotechnical university getting degree, and learning about computers. Not much design activities, mostly microprocessor based system design, 8085 and 8051 families.

90's: Last ten years of the century were strongly influenced by the last Balkan war. One great 2 m band SSB/CW transceiver was designed (Hamtel was located in Germany at that time). It was very stressful decade, finally ending in a Linux world of system administration, and a couple of PIC based projects.