PLJ-8LED-H RF Frequency Counter Cymometer Tester Module 0.1~1000MHz (Backlit Font red)

The media could not be loaded.  This little counter interfaces almost effortlessly to a 1970s-era Ten Tec Triton IV 540 transceiver to add digital frequency readout. I connected the unit’s signal input to the octal accessory plug on the radio’s back panel. I took 12vdc power from the accessory power jack. I set the counter for a 9 MHz IF offset addition, minimum LED brightness, locked to the “low” input, and engaged the low frequency filter. I then installed a jumper on the center two programming interface pins to select the second IF offset and set it to subtract 9 MHz. I set the gate time to 0.1 second for a fast update of the display while tuning and 10 Hz resolution. I wired an SPST toggle switch to the center two programming pins in place of the jumper to select between +- offset depending upon the band in use.The unit is very well calibrated, agreeing within 25 Hz with WWV calibration and the internal radio crystal calibrator. I found the display supported only 1.0 and 0.1 second gate times, despite the description that states there is a third 0.01 second option. The unit also lacks the feature to suppress the least significant digit to prevent constant flickering due the normal instability of the analog VFO in the radio. The voltage regulator runs quite cool powered at 12vdc with LED brightness at the minimum setting. The red LEDs are very readable. I found an added red filter did not improve readability and was unnecessary.Ten Tec made an almost identical add-on external digital display back in the 1970s that functioned exactly like this unit. Of course the radio is still analog and the display is just displaying whatever the analog VFO outputs. However, the digital display allows selecting a frequency within ham band edges without frequent calibration of the radio’s analog dial. Stability was within 10 Hz after an hour of “on” time. This was combined radio and display drift. Impressive! Highly recommended for this specific application.

Be aware you must do a minor repair to make this counter work. There appears to be no final quality control of the finished package product. The power cable and input cable have the black and red wires reversed. At least on both of the ones I ordered here on Amazonand the one I got from eBay. So with all three being wrong, my guess is yours will be wrong also.Finally, be aware that these counters are calibrated only somewhat close. All of mine have been anywhere from 50hz off to one being 300hz off. That probably won't matter for most applications, but if you are doing any kind of RF work it's nowhere near close enough. After calibrating, I find that these counters are extremely consistent after they have warmed up for a few minutes. Typically they are within a 1 hz of target.5 stars if they ever figure out how to make the writing harness correct and calibrate it better from the factory.

The original and replacement failed after 1 week

WARNING !! These work great - great price . The provided I/O cables ( Power / Input ) are wired DIFFERENTLY!! Looking from the TOP ( opposite the decimal points on the LEDs ) install the cables such that the BLACK ( Negative Wires ) is on Top . Verify that the Black wires connect to - and Ground as printed on the PCB . Fortunately there is a protection diode on the power input so if you get the power backwards it will not kill the device ( it just won't work ) . Great products !

I test the frequency counter with ocxo crystal oscillators over 4 hrs for each and the frequency counter showed 10.000002 MHz for a10 MHz ocxo.

I may try a small amplifier to see it that would work. Not a great option though.

Accuracy

Crystal dead, like many other reviews. Waited too long to test out, and now another part to throw away or attempt to repair.