Directional Couplers with RF output and DC output for 145MHz - 435MHz.
pa0nhc.  Ver. 2003 10 03. / .20110306 /  20130509 / 20150217 / 20170929 / 20171231
Site located at : www.pa0nhc.nl

(C) The use, copy and modification of all info on this site is only permitted for non-commercial purposes, and
thereby explicitly mentioning my radio amateur call sign "PA0NHC" as the original writer / designer / photographer / publisher.

Small sized coupler with DC-ouput.

A new design for a factory made PCB.
Small sized coupler with RF output.


Overview Development DIY MASKS Factory made PCBs

Factory made PCBs can be ordered. Ask info at :

Tests (in 1999) on finished prototypes like above showed nearly NO reflected power at 25W transmitter output, when terminated with a good dummy load
. It clearly showed differences in return loss between different types of low power 50/51 ohms terminating resistors, and higher power dummy loads. Good terminators showed up to 30 dB return loss.

        Possible uses :
The RF-output directional couplers + a portophone or signal generator + a step attenuator + a common receiver with the S-meter as indicator, can be used to measure with very low RF power the return loss of  :
- small receiver filters
- large cavity filers
- large helix filters    
    - low pass
    - high pass
    - band pass.
- antenna systems

They also can be used to safely inject RF signals into a live operating
repeater, and measure
- its real practical sensitivity
- the correct action of the CTCSS system
- the squelch action
- large signal handling (blocking). 
- the
duplex filter using a portophone at low power and step attenuators 
    - frequency characteristic
    - up to -120dBc suppression at the notch frequencies
See PI3RTD and pa0nhc cavity filter .

The DC output couplers + the RF power from a transmitter can be used to measure :
- RF transmitter output (1W - 800 W)
- returned power from loads such as antenna's (1W - 800 W)
- to high VSWR to shutdown a power amplifier or driver stage