Thursday, April 25, 2013
Last weekend I assisted to a small ham radio flea market surprisingly with a lot of microwave hardware. Thanks to Andrés EB4FJV, I was able to get a DC to 18GHz Narda crystal detector. My idea was to use it as a relative measurement device, just to peak circuits at maximum output.
Sunday, April 21, 2013
Once opened was easy to spot the failure: The high voltage applied to the tube was around 800 volts. The normal working voltage of the SBM-20 tube is around 400 volts, so 800 volts produces self-triggering, and therefore, the extra counts.
Monday, April 15, 2013
Some days ago I was given a dual SIM chinese Android phone. The LCD screen was broken and the battery was noticeably swollen, so nothing could be usable. I noticed the battery was a Nokia-like battery, even with the same prints on it, but obviously a counterfeit battery.
Friday, April 5, 2013
But unfortunately in this area of the world narrow band work in the 13cm band is done around 2320.2 MHz, and in this frequency most WiFi antennas simply suck.
Wednesday, April 3, 2013
Usually high pitched noises come from the switched power supply. In the past I have found switched power supplies with loosen transformer cores that produced noise just like an speaker.