This RF Layout Reference Design demonstrates good decoupling and layout techniques for a low power RF device operating in the 868 MHz and 915 MHz frequency bands.
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.
This counter from Rohde & Schwarz - Hameg has a 10-digit resolution, Nine measurement functions, External reference input (10 MHz) via BNC connector. It has a Measurement range from DC to 3GHz. It has a user friendly menu with advanced functions.
This is from Sixfab founded in 2016 by a group of makers & engineers. WSN Dev. Kit is a board that combining Arduino and Sub1 GHz communication module with the rechargeable battery functionality. It has Atmega 328 microcontroller and cc1101 868 Mhz radio module.There are also built-in humidity and temperature sensors
Designs and manufactures Communication Appliances along with a full range of Industrial Platform Computers, Panel Device Service etc. They include PICMG, PCI and ISA Industrial Systems. Modular Systems like Qseven, PCM, ETX and COM Express.