LDG Electronics RU-9:1 Unun

LDG Electronics RU-9:1 Unun was designed to allow easy interface of random length vertical and end fed antennas to the LDG line of Automatic Antenna Tuners. This 200 watt Unun also operates as a standalone, meaning that it does not necessarily require a tuner for use on a certain antenna. It may be used with many of your antenna projects where a 4:1 Unun is typically recommended. This model is small and easy to weatherproof for use in the elements.

LDG RU-9:1 Unun specs:

* Ratio: 9:1
* Frequency coverage: 1.8 to 30 MHz.
* Power range: Up to 200 watts PEP
* Enclosure dimensions (WHD): 2.5 x 5 x 1.25 in.
* Weight: 6 oz.

LDG Balun and Unun
User’s Manual
Introduction
Congratulations on your purchase of an LDG Balun or Unun. These quality units greatly expand
the utility of your LDG Automatic Tuner, allowing much greater flexibility in the type of antenna
and transmission line you can use. LDG’s Baluns and Ununs are inspired by the designs of Jerry
Sevick, W2FMI (SK) in his classic book Transmission Line Transformers.
All LDG Baluns and Ununs are rated at 200 watts PEP, and are water resistant; they are intended
for outdoor use. Each weighs 6 oz, and measure 5”x2.5”x1.2”.
Baluns and Ununs
Balanced antennas are electrically symmetrical and do not rely on connection to the ground; an
ordinary dipole is a good example of a balanced antenna. Unbalanced antennas are asymmetrical
and rely on a ground, such as a ¼ wave vertical antenna operated against a ground plane. All
modern radios have unbalanced outputs, and all coaxial cable is unbalanced.
Feeding a balanced antenna with an unbalanced transmission line can lead to unwanted RF
current distribution that degrades performance. Baluns are circuits that match an unbalanced
transmission line to a balanced load, and can adjust the impedance ratio as needed. Ununs match
unbalanced transmission lines to unbalanced loads, also adjusting impedance.
RU-9:1
The RU-9:1 is a 9:1 Unun that allows you to easily match an end-fed long
wire antenna with your LDG Automatic Antenna Tuner. Connection is
made by a 5-way, twist-on binding post; connect the red post to the
antenna. A ground terminal connection is available for an optional
counterpoise or radial system. The RU-9:1 is intended to match a long wire
antenna of 30-135’, with or without a ground.
RU-1:1
The RU-1:1 is a 1:1 Unun intended to help remove unwanted RF from the
coax cable shield. It is normally used as a common-mode RF choke for short
coax cable runs or non-resonant antennas. The RU-1:1 features SO-239
sockets for both input and output.