Coax Common Mode Noise Filter - 1500/5000 Watts, 1.8-60 MHz, -38 dB Common Mode Noise Suppression
Product Details
MPN: CMNF-1500HF
Type: NEW
Country/Region of Manufacture: United States
Filter Power Rating (PEP watts): 1500
Common Mode Attenuation (db): 21-38 db
RFI Suppression Range (MHz): 1.8-60
Insertion Loss (db): .05
# Ferrite Filters: 4
Enclosure Size (inches): 4" x 4" x 2"
Typical Use:: Noise filter at radio end of coax between amplifier and antenna tuner
CMNF-1500HF — Coax Common-Mode Noise Filter (HF, 1.5 kW PEP)
1.8–65 MHz 50 Ω • SO-239 Up to 1.5 kW PEP Amp-safe design
What it fixes
Blocks braid-borne common-mode current that raises the receiver noise floor and causes RF-in-shack symptoms under power.
- Cleaner receive on crowded HF bands
- Reduces RFI paths when driving amplifiers
- Stabilizes multi-antenna stations (braids no longer paralleled)
Where to place it
- At station entry or at amp output, before any switch/splitter.
- Use one filter per feed line entering the shack.
- Short, quality jumpers recommended (RG-213/LMR-400).
Which model should I choose?
- Up to 500 W: CMNF-500-50
- Up to 1.5 kW PEP: CMNF-1500HF (this page)
- Legal-limit/contest: CMNF-5000HF (this page)
- Low-band optimized: CMNF-1500LF / 5000LF
60-second “Do I need this?” test
- Unplug coax; note baseline noise.
- Touch center pin only to radio jack; note noise.
- Touch shell only. If noise jumps, your braid is noisy → filter each line.
| Impedance | 50 Ω |
|---|---|
| Range | 1.8–65 MHz |
| Power | Up to 1.5 kW PEP (allow headroom for digital/RTTY) |
| Connectors | SO-239 in/out |
| Placement | Station entry or amp output; one per feed line |
Duty-cycle: Ratings are SSB PEP. For continuous digital/RTTY or long key-down, lower average power or step up to CMNF-5000HF.
Amp Station Bundle (1.5 kW): 2× CMNF-1500HF + two 3-ft RG-213/LMR-400 jumpers (entry + radio).