It’s often difficult if not impossible to detect RF in mini-power RF circuits such as used in walkie-talkies; generally, service grade test equipment just isn’t sensitive enough. Next time you are working on a CB walkie-talkie and can’t tell if a lower power RF amplifier is working, just throw together a CB Sniffer Probe from remains of the old junk box. Better yet, why not be prepared in advance because all new components will cost less than $10. A small plastic rod about 6 inches long, cemented to L1, will allow you to se the sniffer as a probe. To align, place the sniffer near the antenna of a known good walkie-talkie, key the transmitter, and using an insulated alignment screwdriver adjust trimmer capacitor C1 for maximum brilliance of neon lamp l1.
Parts List For CB Sniffer Probe
C1 – 5 to 30 pF trimmer capacitor
l1 – NE-2 neon lamp
L1 - RF choke, ohmite Z-144 or equiv.
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