A frequency counter is an important part of any electronics service bench where it’s necessary to deal with unknown signals. I used them to verify the operation of my RF signal generator while performing alignments on tube radios, because I’m using period equipment that might not always track on frequency as well as it should.
“Good” frequency counters have also tended to be pretty expensive, but have come down in price a lot lately. I used to use a vintage Systron-Donner frequency counter, from the ’50s or ’60s which still used Nixie tubes. It worked well for a while, and was a Cadillac in its day – four input channels, variable attenuation, ranging and differential measurement between channels. It could compare signals as well as count frequency, pulse and period. It has calibration stickers indicating it was being maintained into the ’70s and was used in telecom service for AT&T. Unfortunately though mine has lost the ability to count, and tracking down the problem wouldn’t really be worth it. It cost $100 when I bought it used at a surplus shop.
I needed a replacement, and there’s really no reason to purchase laboratory-grade equipment that could service telecom grade communications links. Old equipment simply won’t take advantage of the features the high-end counters require, but there is some bad stuff out there at the low end to avoid. I ended up settling on this Victor frequency counter:
It’s a small, Made-in-China unit (with all the labels and controls in Chinese, which makes it much more exciting to use) with range from 0.1Hz to 2.4GHz in three steps. It can only measure one channel at a time, has fixed selectable 20dB attenuation, and is good for 30V DC or 30V P-P AC Coupled input up to 50MHz, and only 3V input from 50MHz to 2.4GHz. Signal level stuff only. Input for low-end is 1M Ohm, input impedance on the high-end is 50 Ohm.
It’s stable, it’s small, it’s easy to use once you memorize the controls – there are only two buttons that really matter – and the best part is it comes in under $100 frequently including shipping. Even if it eventually dies after a couple of years, at that price it’s cheaper to replace than it would be to buy an H-P or other lab unit. It works great with my old equipment, too, accurately measuring the output of my EICO 324 signal generator all the way through its range of 150KHz-435MHz.
Shown here verifying a 450KHz IF signal used for calibrating a radio. Easy, cheap and effective – I recommend this one for use as a general hobbyist device. I guess at this price “it does what it claims to do” is a pretty good endorsement, especially since there’s a lot of junk in the bottom end of the equipment market. Product specifications and distributor finder at Victor’s web site.
8-digit LED display, clear reading
Range and gate time adjustable continuously (100ms – 10s)
Frequency measurement: 0.01Hz – 2.4 GHz
Period measurement: 0.5µs – 10s
Input sensitivity: 30mV(rms)
Power: AC 110/220V ± 10%