Bias Tee AC/DC BOX by Jan OK2ZAW

A bias tee is used to insert AC or DC power into an HF signal to power remote antenna pre-amplifiers (DC), Bi-directional beverages (AC) or other devices. It is usually positioned at the receiving end of the coaxial cable to pass AC or DC power from an external source to the coaxial cable running to powered device. A bias tee consists of a feed inductor to deliver AC/DC to a connector on the device side and a blocking capacitor to keep power supply from passing through to the receiver. Bias tees are used in a variety of applications, but are generally used to provide an RF signal and power to a remote device where running two separate cables would not be advantageous. This box offers something more like: RF High Pass Filter (100kHz), protections, variable attenuator and input common-mode filter.

Main functions:

• Info:
  • Broadband: 0.1 MHz to 60 MHz
  • Variable ATTENUATOR pic
  • Front-end protection with diodes pic
  • This version includes HPF (100kHz) to avoind AC noise to RX
  • Power supply common-mode filter
  • Power supply short protection
  • High voltage and current protections
  • LED diode indication of AC/DC power on the coax
  • LED diode for positive and one for negative voltage
  • For: preamplifiers, Bi-dir beverages, 4-way antenna switch etc
• You can set ATT when you have too high gain of preamp.
• Connectors can be SO-239, F
• BOX size 100x100 mm
• Available as
  • ASSEMBLED and tested
  • KIT : all parts + PCB (OLDER THT version without HPF)
  • PCB (OLDER THT version without HPF) only

Parameters:

• Supply voltage AC/DC up to 24 V
• Supply current up to 500 mA
• Insertion loss lower than 1dB - for minimal ATT
• High Pass Filter > 100kHz ( AC noise limiter)
• Two LED diodes for DC+, DC- (both are AC)

Use:

• Providing an RF signal and (AC or DC) power to a remote device over one coax
• You can use bias tee BOX on the both sides as power IN and OUT from RF coax
• For: preamplifiers, Bi-dir beverages, 4-way antenna switch etc

The measured values

ATT OFF: SWR, insert loss	ATT set to 10dB: SWR, insert loss

Example with Bias-tee AC/DC BOX and 4-way switch:

Example with Bias-tee DC (AC/DC) BOX and RX preamp box (with front-end protections):

Download

Bias Tee ACDC BOX
Schematic and board V 0.1:	sch	brd
Schematic and board V 1.0 (2022):	sch	brd
Attribution-NonCommercial 2.0 Generic