LB3HC

PA0FRI and EA6FJ has made some cool low power HF tube amps with the old and thrusty PL519. Here is a picture taken by EA6FJ. This is actually a nice amplifier that should be quite easy to build for the experienced engineer and experimenter. The benefit of using lower anode voltages is that the tank [...]

Mark over at www.brainwagon.org has posted some interesting info about sending hellschreiber from an Arduino (see Marks image above). He has used KD1JVs oscillator circuit that was originally used for the wireless morse code thermometer project. Mark has written code for the Atmel Tiny 13A uC for Hellschreiber transmission. You can find code on his [...]

Tony CT1FFU and Diogo CT2IRW has released a converter for the Fun Cube dongle. The design is a based on the old NE602 workhorse. One new approach is to use a wideband MMIC amp in the front end. The unit is powered via a USB connector. Looks like this may be a good add on [...]

By popular demand I have posted some pictures from OH8X, Radio Arcala. Enjoy!   This picture (above) gives a good overview over the antennas at OH8X. You can see the M7 and the M1 towers stand out. Notice how small the M6 rotatable tower looks. The M6 tower in not small in real life its [...]

FlexRadio systems is launching new products and new improved software all the time. I have been following the SDR scene for several years now and experimenting with the Softrock 40 and softrock RX-TX as well as some earlier VHF SDRs has been fun. I must say that the offerings from flex-radio is now becoming more [...]

I had some problems of getting my Funcube dongle (purchased dec 2011) to work with SDR-RADIO version 1.5 build 879 (beta). The reason was that the funcube dongle didn’t have the latest firmware. The www.funcubedongle.com webpage is a bit unclear about how to do the upgrade, so here I have written up how to upgrade [...]

I have recently acquired a Funcube dongle software defined radio. The Funcube dongle is a small USB unit that contains a E4000 Silicon Tuner (radio on a chip), a TLV320AIC3104 Audio Codec and a Microchip 24FJ32GB002 16bit Microcontroller. This small USB device gives me coverage from 64 to 1700 Mhz with some small gaps according [...]

NOAA has a nice tool that can be of utility for radio amateur operators that are interested in how the geomagnetic field will be affected and how strongly it will be affected. It is now possible to see when there is a high likelihood that the K and AP indexes will rise. By processing the [...]

I have posted a simulation for investigating energy dissipation when a high power transmitting vacuum tube arcs over from anode to grid (A-G arcing). I have simulated energy dissipation in the glitch resistor, in a simulated SCR based crowbar circuit and finally in the vacuum tube itself. In this case an Eimac YC-179 high power [...]

I have posted the equivalent schematic for my hipot tester. The design is based loosely on some ideas from K8CU and AG6K.  However, I have simplified the circuit somewhat and used different components. The mechanical encapsulation is also different. I used LTspice to verify the tester before building it. The schematic is from the LTspice [...]