DX Engineering TWIG QRP 9:1 UNUNs

The DXE-TWIG-9-1 QRP UNUN (Unbalanced-to-Unbalanced transformer) matches a high-impedance, non-resonant end-fed/random wire antenna (33 to 84 feet long) to the 50-ohm unbalanced load required by amateur radio transceivers. The DXE TWIG-9-1 covers 1.8–30 MHz and is ideal for portable (QRP) or HOA-restricted antennas. The connector on the DXE-TWIG-9-1 is a BNC female to mate with the recommended 35 to 50 feet of coax cable, which is used as the counterpoise. In some cases, an external wide range tuner may be needed. This UNUN may not provide a perfect 1:1 SWR on all bands without an additional tuner and may experience heating at higher power due to impedance mismatches.

Typically, 9:1 UNUNs are used for:

Random Wire Antenna: Long wires of specific non-resonant lengths (e.g., 29, 35.5, 41, or 71 feet) designed to avoid an electrical half-wave, or multiple of a half-wave, on any amateur band.

End-Fed Long Wire: General-purpose long wire used for wideband receiving or multiband transmitting where an antenna tuner is available.

Inverted "L" or Sloper Configuration: When these are fed as non-resonant wires rather than resonant half-wave radiators.

Tips on How to Use the 9:1 QRP UNUN as a Random Wire Antenna

Select a "Random" Length: Do not use resonant half-wave lengths. Popular lengths that avoid resonance on amateur bands include e.g., 29, 35.5, 41, or 71 feet.

1. Connect the Antenna Wire: Attach your long wire to the element wire terminal of the UNUN.

2. Use an Antenna Tuner: Because a random wire is never perfectly resonant, you may have to use an internal or external antenna tuner to achieve a low SWR for your transceiver.

3. Placement: Mount the UNUN near the ground or on a short support and run the element wire as high and clear of obstacles as possible.

The antenna shown in this manual was tested using the optional 24 or 26 AWG wire such as CEW-VIZ24-YEL100 stranded copper, PVC insulated, high visibility yellow antenna wire.

The coax cable (with BNC connectors) is recommended to be 35 to 50 feet in length since the coaxial cable shield is used as the counterpoise. The antenna can be installed in different configurations. Wire lengths will vary depending on the installation and antenna design chosen.

This is a low power (QRP) antenna system impedance matching UNUN which handles 25 Watts on SSB, 10 Watts on CW and 5 Watts on digital modes when the antenna SWR is less than 2:1 without the use of an antenna tuner.