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Line Comms 9:1 UNUN impedance transformer with SO239 connector and earth terminal – Radioworld UK
Line Comms 9:1 UNUN impedance transformer with SO239 connector and earth terminal – Radioworld UK
9:1 UNUN 1kW 1.8-54MHz for Long Wire Antennas Ham Radio
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Line Comms 9:1 UNUN impedance transformer with SO239 connector and earth terminal – Radioworld UK
9:1 UNUN 1kW 1.8-54MHz for Long Wire Antennas Ham Radio

Sigma Euro-Comm Antennas – HF & CB Radio Base.

9:1 UNUN 1kW 1.8-54MHz for Long Wire Antennas Ham Radio

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Product code: 9:1 UNUN 1kW 1.8-54MHz
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£54.95
12 Months 14.9% APR
£5.49
£4.74
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£54.95
18 Months 14.9% APR
£5.49
£3.16
£62.32
£54.95
24 Months 14.9% APR
£5.49
£2.37
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£54.95
36 Months 14.9% APR
£5.49
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£54.95
48 Months 14.9% APR
£5.49
£1.18
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£54.95
12 Months 19.5% APR
£5.49
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£64.59
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18 Months 19.5% APR
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£54.95
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£2.46
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£54.95
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48 Months 19.5% APR
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£1.23
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Line Comms 9:1 UNUN impedance transformer with SO239 connector and earth terminal – Radioworld UK

9:1 UNUN 1kW 1.8-54MHz for Long Wire Antennas Ham Radio


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This UNUN provides an efficient feed point for a long‑wire radiating element, transforming the high impedance of approximately 450Ω down to a level far closer to the 50Ω expected by modern transceivers. Designed for reliability and ease of installation, it allows operators to deploy an effective end‑fed wire antenna even in limited space.

The unit features a SO239 connector for your coaxial feed line and two heavy‑duty machine screws with butterfly nuts for attaching the radiating wire and the earth connection. The longest available wire should be connected to the radiating terminal, while the terminal marked with the green earth label must be bonded to a suitable ground. This reduces static build‑up, improves noise performance, and provides a safe discharge path for atmospheric charge.

For best results, mount the feed point as high as possible on a pole, wall, or suitable support. Run the long‑wire element out in a straight, horizontal line where space allows. If this is not possible, the wire may be dog‑legged, sloped, or routed creatively to suit your available space — performance remains excellent across a wide range of installations.

Connect the coaxial feed to your ATU, then onward to your transceiver. Once powered up, make final tuning adjustments and enjoy reliable multiband operation from a simple, effective long‑wire system.

UNUN Long‑Wire Antenna Installation Guide

1

Prepare the UNUN and Identify Terminals

Start Here

Correct identification of the feed and earth terminals ensures safe and efficient operation.

  • Locate the SO‑239 connector for the coax feed line.

  • Identify the two machine screw terminals with butterfly nuts.

  • The green terminal is the earth/ground connection.

  • The other terminal is the long‑wire radiating element connection.

2

Connect the Long‑Wire Radiating Element

This wire forms the actual antenna and should be as long and as straight as possible.

  • Attach the longest wire available to the non‑green terminal.

  • Use ring terminals or tight wrapping to ensure a secure mechanical and electrical connection.

  • Aim for a straight, horizontal run, but dog‑legs, slopes, or bends are acceptable if space is limited.

3

Install the Earth/Ground Connection

Safety

A proper earth reduces static, improves performance, and provides a discharge path for lightning and atmospheric charge.

  • Attach a suitable length of wire to the green‑labelled terminal.

  • Run this wire to a ground rod or earth stake.

  • Ensure the connection is tight and weather‑resistant.

  • This step reduces static pick‑up and provides a direct path to Earth for charge dissipation.

4

Mount the Feed Point

Raising the feed point improves radiation efficiency and reduces ground losses.

  • Fix the UNUN as high as possible on a pole, wall, or mast.

  • Ensure the unit is mechanically secure and protected from strain.

  • Maintain a gentle strain relief on the long‑wire element to avoid pulling on the terminals.

5

Route and Connect the Coaxial Feed Line

The coax carries RF between the UNUN and your station equipment.

  • Connect your coax to the SO‑239 on the UNUN.

  • Route the coax safely back to the shack, avoiding sharp bends.

  • Connect the coax to your ATU (Antenna Tuning Unit).

  • From the ATU, connect to your transceiver using a short patch lead.

6

Tune and Operate

Recommended

Final adjustments ensure the system is matched and ready for transmission.

  • Power up your transceiver and ATU.

  • Select the desired band and tune for minimum SWR.

  • Once matched, the system is ready for normal operation.

  • Periodically check all outdoor connections for weathering.

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