Palomar Engineers Common Mode Noise Filter, 500w, 1-6MHz - CMNF-500-50

For coax feed lines with receive and transmit signals, you will love the small size, wide frequency range and excellent attenuation of common mode noise interference

• Reduces broadband common mode receiver noise* picked up on the outside of the antenna coax feed line.
• Wide frequency range works on all brands of radios and coax fed antennas from 1-60 MHz
• Common mode noise rejection up to -38 DB (3-6 "S" units) depending on frequency
• Simple plug & play installation: plug a short jumper from the CMNF-500HF to your radio and plug the feed line into the other SO-239 CMNF-500HF input. Either connector can be input or output. Rated at 500 watts PEP, 50 ohm input/output
• will work with Bias-T antenna switches and will pass DC voltage from input to output with no attenuation
• bidirectional input/output connection - you can't get it wrong!

* not effective for noise from AC power lines or noise received directly by antenna

Installation Note:

For best results, and to reduce co-interference between choked and unchoked coax feed lines with multiple antennas, ALL antenna feed lines entering the radio room need to have a separate feed line choke particularly if they are at a different frequency then HF, like VHF or UHF.

If you use a antenna switch for multiple antennas in the 1-61 MHz range, place the CMNF-500 in the "common" line of the antenna coax switch and the receiver, or better yet, use a filter in each line BEFORE the antenna switch to isolate the coax braids from each other!

Got Common Mode Noise? Not Sure? Find out now by clicking link below:

Palomar Engineers Common Mode Noise on Coax User Diagnosis Test (external link)

If you use a higher powered transceiver over 500 watts PEP or use an amplifier, consider the CMNF-1500HF (1.5KW PEP) or CMNF-5000HF (5KW PEP) placed at the output of the antenna switch.