Welcome on DL4UNY's Radio-Page!
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...DL4UNY on 2m/70cm... I didn't focus much on bands higher than 50MHz because I never had an outstanding QTH for VHF operation and the bit of 2m contest activity I did was just for fun, to work some friends. Therefore, I never used any special equipment to make QSOs on 2m, just used what was available. I'm an RF engineer, working at Rohde&Schwarz, developing RF frontends and synthesizer for high class spectrum analyzers. Therefore of course I'm quite familiar with frequencies beyond 50MHz ;) and after some time I felt the strong desire to design my own VHF/UHF Radio equipment. From the engineering point of view, a simple 28-144 transverter is very easy, but I didn't want anything thats already available on the market. I wanted to build my own high class bidirectional converters. First, I wanted to design and build a stable low phase noise 116MHz source with high power output (> 17dBm output power) to work as LO for the following converter. It took me a while to find the right crystalls to do the job and eventually ordered customized 116MHz quartz crystalls from Axtal. I designed a oscillator circuit for low phase noise and made a PCB which can be used as a submount or separate module for the next stage (converter, in my case)  Oscillator, heater and crystall are enclosed in a thick alloy enclosure:  By now, I have completed about 25 116MHz oscillator units and the plot below shows the typical phase noise of them: 1 Hz: > -50dBc 10 Hz: > -85dBc 100 Hz: > -115dBc residual noise: > -165 dBc  Just message me in case you are interesed in purchasing an oscillator or parts. 10m <-> 2m Transverter In order to extend the frequency range of my TS-590 and FT-1000MP I needed a transverter. I didn't want to buy a ready-made solution for several reasons: - the commercial high-performance transverters are too expensive to me, neither I'm a passionated VHF contester nor DXer, I just 'want to be active' but I want best performance possible - I wanted to make my own gear - focus on parameters that are important to ME, such as bandwidth (for an SDR), compatibility to other bands (using 6m/4m/70cm ... with minor circuit but no layout changes) - I'm an RF-engineer ;) After developing the 116MHz signal source for LO I could continue designing the up- and down converter stages. Checking the list of MMIC amplifiers I have availabe at home, I quickly computed the expected dynamic on 2m:  A noise figure of about 2dB and OIP3 of about 33dBm doesn't sound so bad for the beginning. So I started designing the filters according to my block diagram. The result can be seen here: (interactive BOM is here)
Not bad: 2dB noise figure and 31dBm output IP3 @ 27dB gain. Physics works Assembly instruction and Description (in German) is available here. Just message me in case you are interesed in purchasing a complete transverter or parts. |
