ANTENTOP- 01- 2018 # 022

RF Sniffer

Again E- Bay was the source of the diodes. I found there 50 each excellent UHF TOSHIBA 1SS315 type diodes for 5 USD shipping included. It was small SMT parts but in recent times almost every electronic part comes in SMT package. Table 1 shows main parameters for the diode. Forward voltage for the diode is only 0.25 V (Forward voltage for Silicone diode is 0.7 V, for germanium is 0.3 V), so the diode could catch low level RF voltages that would be present on the antenna- inductor L1. Total capacitance for the diode is 0.6 pF, so the diode may work in my FSM on frequencies up to 3-GHz.

1N35. Made in USA, SYLVANIA

Table 1 Electrical Characteristics of 1SS315

1SS315 diode showed very good result during my experiments. After that I made finished design of the device. But... the finished design means a breadboard PCB attached to the internal contact screw of the 100- micro- ampere meter. Newer any cabinet there was around. Such design allows me do different experiments with the RF Sniffer. I changed length of L1 (length of wire of the L1 should be equal to wavelength of the signal to be catch) for different frequencies, I may remove board with loop antenna from the meter and place antenna in some hard accessed places to catch RF. I install RF choke with whip antenna instead of L1 to turn the device to sniff HF (1.8- 50.0- MHz) and VHF- UHF (145 and 430- MHz). Figure 2 shows modified RF Sniffer.

RF Sniffer: Front View

Figure 2 Modified RF Sniffer

RF Sniffer: Rear View

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