- 2 -
Control Circuit:
The RT-11 requires external control circuitry, which is not provided with the basic
tuner. You have three options:
1. You can use the optional LDG remote control unit.
2. You can use special cables, available from LDG, to interface your RT-11 to Icom, Alinco or
Kenwood TS-50 transceivers. You can also make you own control cable for Icom or Alinco
transceivers; complete wiring diagrams for these cables are available on the LDG web site.
3. You can “homebrew” your own controls. The RT-11 interface is designed with simplicity in
mind; you can easily construct control circuitry to customize the tuner to your station and
methods of operation.
You must employ one of these three options to control your RT-11. If none of these options are
available, you can still use the tuner, but only in Auto mode with no direct control (see below under
Pin 4 specifications for details).
An important word about power levels:
The RT-11 is rated at 125 watts peak power. Many
transmitters and transceivers output more than this, and even a small amplifier can output far more
than 125 peak watts; this will
definitely
damage your RT-11. Be sure to observe the 125 watt peak
power limitation for CW and SSB operation (50% duty cycle).
A word about “foldback” circuits
: Many radios have automatic foldback circuits to protect their
RF amplifier stage from excessive reflected power; the foldback circuit automatically reduces power
when the SWR is high. If your radio lacks a foldback circuit, you must never exceed 25 watts while
tuning your RT-11; higher power levels could damage the tuner. Most modern solid-state radios
have foldback circuits. However, many older radios, any kind of tube radio, most solid state
amplifiers and all Ten-Tec transceivers lack foldback circuits. Consult your radio’s manual to find if it
has a foldback circuit, and observe the 25 watt tuning power limit if it does not.
Control Interfaces
: The RT-11 has three connections: coax in from the transmitter, coax out to
the antenna and the control interface. The coax in and out connectors are standard SO-239
sockets for use with standard PL-259 coax plugs. The control interface is a standard male DB-9
connector. The remote interface cable will connect using a standard female DB-9 connector.
The pinout for the DB-9 connector is:
1
+12 volts DC @ 250mA
2
Bypass mode select
3
Tune mode select
4
Auto/Semi mode select
5
Tune LED
6
1.5 LED
7
Radio Out (used only when directly controlled by Icom or Alinco radios)
8
Ground
9
Ground
Control functions are invoked by grounding the relevant control pin to ground at Pins 8 and 9. LED
anodes are to be connected to pins 5 or 6. The LED cathodes are connected to ground.
Summary of Contents for RT-11
Page 2: ......
