MAD-Digimode USB interface

The need of an universal PC/radio interface had triggered me to develop this board. Even at the first version I’ve already sold out all the available units so, actually I’m very happy about how it was wellcomed by Ham Radio operators. What differentiate this board from any other commercia board?

  • Fully opto-insulated CI-V / CAT interface for Yaesu and ICOM radios 3kV ESD rated
  • Fully opto-insulated PTT/Key output 3kV ESD rated
  • State-of-the-art Bourns audio coupling transformer with -0.3dB flatness between 200-3000kHz band 3kV ESD rated
  • Fully separate PC/radio masses
  • Universal radio connector on DB9 female socket. Just wire the cable according to your radio pinout!
  • Two separate USB ports one for radio control and PTT/key and one for Audio stream
  • Integrated USB audio codec: it acts as an USB audio card leaving in peace yours computer one!

FTDI is the manufacturer of the USB UART chip that this board uses for the CAT/CI-V and PTT. It’s not a fake chinese copy. You can use MProg 3.5 software from FTDI to modify lines polarities if needed like in case of CI-V reverse polarity signals. You can download MProg >>HERE<<

This first version have no enclosure available, neverthless it works without RFI issues. I’m planning to make a 3D printable model for my second revision.

Here you can download it’s manual as pdf >>HERE<<

It’s drivers for audio and FTDI chip are >>HERE<<

This is the procedure of how to use it on Windows 7 & 10 with Ham Radio Deluxe

From “System device manager” you have to identify the “USB Serial Port” and put it’s identification number “COM22 as example” into HRD startup config dialog. Select also your radio manufacturer, model and baud rate.

Once the HRD to radio connection successed you can configure the “PTT” line as active on “RTS” line asserted. Sometimes thisis not needed because HRD can assert software PTT triggering.

In DM780 open the settings and use PTT by HRD option that you’ve already configured.

The USB audio card is avaiable as audio in/out. Please deactivate mike AGC otherwise your signal will be degraded.

SiPM super simple spectroscopy

Recently I’ve tested this super simple circuit capable to collect pulses from a SiPM and amplify and pulse-shape them. The pulse shaper Tau constant is 250uSec, this way the resulting shaped pulse could be directly sampled by a PC audio card via Mike input line.

The resulting prototype was made by etching it over a single side bakelite PCB board.

There is no 32-45V power supply for the SiPM polarization. I’ve obtained it by a series of 4x 12V alcaline batteries followed by a linear regulator. SiPM diodes are very sensible to supply noise… batteries in their simplicity provide excellent noise performance.

The shaped pulse looks good and performs well. Tested with my PC soundcard and an 8x8x50mm CsI(Tl) crystal.

FWHM is acceptable. The opamp used must be swapped with something with better bandwidth gain.

DP-5B geiger manual

This is an ultra short user guide for cold war CCCP made DP-5B geiger counter.

The battery elements are located into a bottom compartment. You can get them by opening and splicing the 3x 1.5V elements of a 4.5V flat battery pack. I’ve then wrapped with heathshrink pipe to be insulated against each other.

The first thing to do after switching on is setting the voltage converter. Actually that’s the first position after had clockwise rotated the main selector. The needle must be into the black mark zone of the scale. Use the voltage regulation knob carefully… the “peak'” of the correct position is very sensible.

The second thing is rotate main selector to the first position of the lowest scale. You must do that to zero the instrument. Now you can measure gamma or beta sources and change the various scales.

This is with gamma filter off.

Gamma filter on and 0 because of background.

This is a radium tube with strong gamma emission. I’ve shut down my lab’s light to show the phosphorescent dials.


This is with backlight ON.

The device have it’s own check source. 100kBq Sr90 under a protective cover that can be rotated to put the probe into a precise position.