Home Theater RFI Kit

Coax Common Mode Noise Filter - 1500/5000 Watts, 100 KHz to 30 MHz, up to -38 dB Common Mode Noise Suppression!

CMNF-1500LF
$89.95
In stock
1
Product Details
MPN: CMNF-1500HF
Type: NEW
Country/Region of Manufacture: United States
Filter Power Rating (PEP watts): 1500
Choking Impedance (ohms): 1000-6500
Common Mode Attenuation (db): 21-36 db
RFI Suppression Range (MHz): 1.8-60
Insertion Loss (db): .05
# Ferrite Filters: 5
Enclosure Size (inches): 4" x 4" x 2"
Typical Use:: Noise filter at radio end of coax between amplifier and antenna tuner

CMNF-1500LF for transmitter/receiver coax lines up to 1500 watts PEP - 100 KHz - 12 MHz, Up to -38 dB Common Mode Noise Suppression!

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 200 KHz to 7 MHz

- Common mode noise rejection up to 20-36 DB (3-6 "S" units) depending on frequency

- Simple plug & play installation: plug a short jumper from the CMNF-1500LF to your amplifier output and plug the feed line (or a jumper to your antenna tuner) into the other SO-239 CMNF-1500LF input. Either connector can be input or output. Rated at 1500 watts PEP.

- will work with Bias-T antenna switches and will pass DC voltage from input to output with no attenuation

* 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 .2-7 MHz range, place the CMNF-1500LF in the "common" line of the antenna coax switch and the antenna tuner/amplifier.

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

Palomar Engineers Common Mode Noise on Coax User Diagnosis Test




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TECH NOTE: We also stock RFI kits to protect effected devices such as garage door openers, computers (laptops, desktops), dsl/cable routers, ethernet hubs and many more devices. If you run a high powered RF amplifier in your ham station also consider a linear amp RFI kit which will cut down RFI transmitted by your station. Remember there is always a “transmitter” and a “receiver” of RFI and the quest is to find and choke the “path” the RFI has selected – you need to add ferrites to both the transmitting side and the receiving side to eliminate RFI problems. The RFI-HTS kit only helps suppress RFI on the receiving side.

Typical RFI Problem/Solution:

Hello,
I am Larry, a ham operator and I am having interference issues with
my Direct TV system.
My station is a FT450D through an Ameritron ALS-600. From the amp
through a coax switch  to choose between an OCF dipole or an Hustler
5BTV vertical. Any power over 100 watts and my DTV goes off the air
and must completly reboot/format. Coax is RG-8. The DTV dish is
pointed away from the dipole and separated by about 25'. DTV was
totally useless! They suggested I not talk on the radio while she is
watching TV!  Please help me with a reasonable, cost effective
soultion. (The wife gets really pissed when I shutdown the tv!)

Thank you,

Larry 

 

Hi Larry,

Your RFI problem is quite common and is usually a sign of either a radiating coax feed line or reception of your radiated signal (source) by the Direct TV (the victim) through either the AC power lines acting as “antennas” for your ham signal or the coax braid of the satellite antenna acting as an antenna for your signal.

The solutions are straight forward:

1. To make sure your feed line is not radiating you need a feed line choke at each antenna feed point (also makes your antenna work better since it is not using the coax as part of the antenna).  You can use our simple Kit 110 with 5 snap on chokes on each antenna for this purpose.  Part # Kit 110 at $27.50 each – one for each antenna.  These chokes will keep your feed line from radiating and coupling into your ac power lines.  INFO HERE

2. The radiation from your antennas themselves may also be getting into the ac power lines and coax braid of the Direct TV antenna so you need to protect the victim receiver.  Depending upon the sophistication of your direct TV setup (e.g. home theater, dvd, tape player, sub woofer speakers, etc), the path of the RFI may be coming thru the AC power lines of any connected device to the video including the video monitor itself!  To help solve this problem we have a home theater RFI kit for up to 5 devices (you need a minimum of two – one for the Direct TV receiver(AC and coax input) and another for the video monitor AC power lines and HDMI or video input cable.  Our kit part # is RFI-HTS.  INFO HERE

These items should help reduce the RFI and let you operate on the air while your wife watches TV.

Bob Brehm, AK6R

Chief Engineer