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COMTEK COM-LI-11140 Line Isolators COM-LI-11140

Line Isolator, Dual Core, 2 kW CW, 5 kW PEP, SO-239 Connectors, Provides RF Isolation, Each

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Brand: COMTEK
Manufacturer's Part Number: COM-LI-11140
DXE Part Number: COM-LI-11140

Frequency Range: 1.8-54 MHz
Ratio: 1:1
Termination Impedance (Ohms): 50
Termination Location: Top and bottom
Termination Type: UHF female, SO-239
Enclosure Type: Weatherproof NEMA box
Enclosure Material: Plastic
Core Type: Coax/Dual core
Power Handling (CW/SSB): 2 kW/5 kW
Enclosure Width: 4.000 in.
Enclosure Height: 4.000 in.
Enclosure Depth: 2.000 in.
Quantity: Sold individually.
Notes: Always use a Balun Mounting Bracket to remove coax and antenna strain from the plastic balun enclosure.
Lowest Band of Operation: 160 meters
Highest Band of Operation: 6 meters
Antenna Mounting Type: Adapter bracket

Additional Information

Antenna Type Compatibility
50 ohm feedline system
Dipole, coax fed, resonant
Dipole, inverted vee, resonant
Dipole, multi-band resonant
Dipole, trap
Inverted vee, coax fed, resonant
Log periodic, 50 ohm coax feed
Log periodic, 50 ohm, direct coax feed
Mobile vertical antenna, HF
Vertical, 50 ohm, direct coax feed
Vertical, resonant
Vertical, trap
Yagi, 50 ohm, direct coax feed
Yagi, gamma matched
Yagi, hairpin/beta matched
Yagi, trap tri-bander

COMTEK COM-LI-11140 Line Isolators are based on the Jerry Sevick, W2FMI design to prevent unwanted RFI in 50 ohm, coaxially fed antenna systems. They provide excellent feedline decoupling and low loss performance from 1 to 60 MHz. COMTEK Line Isolators are power-rated for 2 kW continuous, 5 kW intermittent duty, with significantly higher common mode impedance and a larger effective core area than similar line isolators, including conventional enameled wire or bead baluns.

COM-LI-11140 Line Isolators provide these benefits:
- Higher power handling with lower loss – delivers more RF power to the antenna
- Improved antenna bandwidth – easier on the radio and tuner
- Compensate for a less than optimal ground system – stop feedline radiation
- Reduced RFI – less interference to and from your radio

If you are having trouble with RF interference, such as disturbing audio, video or computer equipment in your house or your neighbors', a "hot" mic or audio distortion while transmitting, then it is likely that your feedline is acting like part of your antenna system. While most common advice is to improve the station's RF ground, the root of the problem is poor isolation of the feedline from antenna currents.

COMTEK Line Isolators are excellent feedline current chokes that may be used with many types of 1.8 through 50 MHz antennas including beams, dipoles, verticals, verticals with elevated radials, center-fed vertical dipoles and other antennas. Normally, a COMTEK Line Isolator is installed at the antenna end of the feedline. This will substantially reduce unwanted feedline radiation or unwanted signals without the need for an improved antenna ground system. This is especially true for center-fed verticals or any antenna where the feedline parallels an active antenna element. In other cases, as the coax feedline travels through the near-field of the antenna, the current can be re-introduced to the feedline after the balun. In those cases, where the SWR is low, reduce feedline radiation and improve reception with a COMTEK Line Isolator installed at the shack end of the feedline.

The COMTEK COM-LI-11140 Line Isolators come in a NEMA case with gasket mounted PTFE / Silver SO-239 connectors. Both ends of COMTEK Line Isolators are isolated SO-239 connectors. These Line Isolators are not affected by moisture and may installed and used outdoors in all types of weather including heavy rain, when positioned vertically so water or condensation will drain from the case through the four small weep holes located on the bottom. However, COMTEK Line Isolators may not be immersed in water.

For mounting a COMTEK Line Isolator directly to a boom, pipe or wall, order DXE-BMB-4P, a custom made, patented* Balun Mounting Bracket and Stainless Steel Hardware Kit. When used with optional DXE-ECLS Stainless Steel Band Clamps with Studs, you can mount this Balun Mounting Bracket on a boom or pipe ranging in size from 1/2 in. through 3-1/4 in. The DXE-BMB-4P may be mounted to a wall or wooden post using the appropriate size user-supplied wood screws.
*US Patent No. D597,086

Stop common mode current on the feedline and prevent RFI with COMTEK COM-LI-11140 Line Isolators from DX Engineering. Order yours today!

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Most Helpful Reviews Review this Product

3 Customer Reviews for COMTEK COM-LI-11140 - COMTEK COM-LI-11140 Line Isolators

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Choke, line isolator, for 6 meters

DX EngineeringDX Engineering Verified Purchase

COM-LI-11140
Seems to working well. Difficult to say if it is helping the antenna pattern. Does not appear as if there is RF on the shield, and no apparent SWR impact with the use of the choke.

1 of 1 found this review helpful.

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Reviewer: from VA

Date: May 29, 2018

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Well built

DX EngineeringDX Engineering Verified Purchase

COM-LI-11140
Nicely built and high quality. It is working well. A minor nit-pick is that the label (and/or cover) was upside-down with respect to the drain holes. I re-positioned the cover.

1 of 1 found this review helpful.

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Reviewer: from MI

Date: November 14, 2017

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RF Line Isolator

DX EngineeringDX Engineering Verified Purchase

COM-LI-11140
Installed one at the feed point of my antenna and where the line comes into my shack. Totally eliminated RF interference that was coming into my son's headphones when using my amp. SWR unaffected. Good Reports.

0 of 0 found this review helpful.

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Reviewer: from CA

Date: January 29, 2019

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Most Recent Reviews

RF Line Isolator

Installed one at the feed point of my antenna and where the line comes into my shack. Totally eliminated RF interference that was coming into my son's headphones when using my amp. SWR unaffected. Good Reports.

Published on January 29, 2019 by FRED

Choke, line isolator, for 6 meters

Seems to working well. Difficult to say if it is helping the antenna pattern. Does not appear as if there is RF on the shield, and no apparent SWR impact with the use of the choke.

Published on May 29, 2018 by DARYL

Well built

Nicely built and high quality. It is working well. A minor nit-pick is that the label (and/or cover) was upside-down with respect to the drain holes. I re-positioned the cover.

Published on November 14, 2017 by GREG

+See All 3 Reviews
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