tvsplitters

Television feed line splitters are small gold coloured cast aluminium boxes with 3, 4, or 5 built-in F-type coaxial connectors. The top cover can usually be pried off to reveal a small VHF balun transformer inside. F-type connectors for connecting cable to these devices are the least expensive of coax connectors. RG-6 coaxial cable is 75 ohm impedance, good for up to 3 GHz and usually readily available as surplus from the cable TV industry (check with your local cable guy, or look in the trash bin behind cable TV offices).

A number of small but very useful devices can be built inside these miniature chassis with integral coaxial connectors:

• VHF/UHF Splitters (original application)
• HF signal splitters or combiners (change the balun to a T37-6 type)
• HF impedance transformers (just requires a toroid core and windings)
• HF un-balanced to balanced adapters (toroidal baluns)
• Double Balanced Modulators or Detectors (diodes plus two toroids)
• Single-ended detectors or modulators (Diodes, toroids, and R & C)
• Attenuators or isolators (Resistive attenuators)
• RF auto-transformers or multi-winding transformers (just toroidal inductors)
• Broadband Amplifiers (Transistor or FET and associated circuitry)
• Signal Switching modules (add a slide switch to the cover plate)
• Remote antenna amplifiers (feed power up the coax)
• Remote sensors (a remote signal strength sampler for your antenna range?)
• Encapsulated oscillator modules, with control and modulation inputs
• Remote mixers (down-converters) for HF, VHF, or UHF use (power via coax)
• Noise generator module (well shielded, with coaxial output)
• Video switching module (use diode or FET switches and DC to operate them)
• Pulse generator module for TDR measurements of coax & antenna circuits

That is just a few of the potential uses that come to mind. What can you add to the list?