Here is a vintage frequency counter that you can build and use it for learning and experiments in your home or office lab. The front end circuits have to be studied. This will help young enthusiasts learn some basics of instrumentation. - delabs Notes
Ramsey CT-90 - Portable Frequency Counter
The CT-90 is a laboratory quality frequency counter that is capable of use in the lab as well as in the field. Utmost care has been taken in all the design stages to insure that sensitivity and reliabilty were not compromised. The CT-90 has been specifically built for the critical user, as demonstrated by; special timebase options, nine digit display, three gate times, and a count hold feature.
The CT-90 is ideal for portable usage. Leading zero blanking and the micro power oven (optional) allows 2-4 hours of continuous operation using the internal battery supply.
Operation; Operation of the CT-90 is very simple, simply connect your input signal to the proper input jack (10, 60 mhz or 600 mhz) and select the range and gate time. All switches, except the external time base switch (optional) are mounted on the front panel in easy view of the user. A description of the front panel controls follows.
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