This handy item, purchased recently on eBay, can be useful for those needing an inexpensive frequency counter and tone code analyzer.
It comes complete with battery, three inch telescoping antenna — but no instructions. Size is 4 x 2 3/8 x 1 inch and comes in camo color.
To turn on just press the button on left side to reset the unit, then hit the transmit key of the test radio, and in a second it reads the frequency and tone. It shuts off automatically after about 10 seconds. The back cover has a convenient hole for hanging the unit.
As per the manufacturer it covers 50 MHz – 2.4 GHz and I have tried it on 2m, 70 cm bands, and on the FRS band. It seems to work fine. Can’t say how long this unit will last but if someone wants a much better and much more expensive unit, Optoelectronics makes one for nearly $500: http://www.optoelectronics.com/#!cd100/c6qo