Author Topic: Tenma 72-5000 frequency counter sensitivity problem  (Read 414 times)

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Offline Radio Tech

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Tenma 72-5000 frequency counter sensitivity problem
« on: June 29, 2016, 01:11:56 pm »
A while back I picked up this counter for free.  A few days ago I tried using it for the first time. Was aligning a radio and it would not lock onto the oscillator, grabbed my old B&K 1801 and no problem.

Yesterday I decided to test the counter and see what the problem is. Connecting my SG at full throttle (20K) to input A it read the 100MHz signal.  At 15k it falls off.  Tried the same on input B and it falls off at 10K.  This thing is deafer than I am.

Just looking over the board it appears to be two different circuits for A & B. With the same problem.  My guess is the two signal paths comes together further in the circuit and this is where the problem is.  Without a schematic I am shooting in the dark. Anyone seen this issue before?


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