Ten-Tec 238C manual
Part #74428
First release, June 2009. Printed in U.S.A.
CHAPTER 1
MODEL 238C INSTALLATION
Model 238C is a high power antenna tuner
that uses an adjustable reactive network for
matching the unbalanced 50 ohm output
impedance of transmitters and transceivers
to a variety of balanced and unbalanced
loads. It is usable over a frequency range of
1.8 to 30 MHz. Provision is made for
selecting one of four antennas or for by-
passing the matching network. A cross-
needle SWR and wattmeter with switchable
200 and 2000 watt scales and selectable
peak and average power output reading is
included.
UNPACKING YOUR NEW TUNER
Examine your model 238C for signs of
shipping damage. Should any damage be
apparent, notify the delivering carrier
immediately, stating the full extent of the
damage.
Retain all damaged cartons if damage is
apparent. Liability for shipping damage
rests with the carrier. We also recommend
that you keep the carton and packing fillers
in the event that storage, moving, or
shipment becomes necessary.
The following hardware and accessories are
packed with your 238C. Make sure that you
have not overlooked anything.
(1) #23160 Capacitor, 1000 pF, 1 kV
(1) #38088 .062” hex Allen wrench
(1) #74020 Warranty card
(1) #74428 238C Operator’s Manual
TRANSMITTER CONNECTION
The model 238C is designed for connection
to transmitters having a 50 ohm nominal
output impedance. Connect the coaxial
output of your transmitter to the SO-239 type
INPUT connector on the rear panel of the
tuner with a 50 ohm coaxial cable.
GROUND CONNECTION
Connect your station ground system to the
GND wing nut terminal on the rear panel of
the tuner with heavy braid or wire. The
ground connection should go directly to the
earth ground system using as short a lead
as possible.
ANTENNA CONNECTIONS
Connect antenna transmission line(s) to the
appropriate terminal(s) on the tuner as
follows.
For 50 ohm coax-fed antennas (unbalanced
transmission lines) use ANT 1, ANT 2, ANT
3 or ANT 4.
For a single wire antenna connect to
SINGLE WIRE terminal. The SINGLE WIRE
terminal uses the ANT 4 antenna
connection.
For balanced feedline systems, adding a
jumper from SINGLE WIRE to one of the
BALANCED LINE terminals as shown on the
rear panel is required. A tin-plated steel
jumper for this purpose has been provided.
It is attached to one wing nut connector on
the back; if balanced line will be used, attach
the other side of the jumper to the other
wing nut. Then connect the feedline to the
two BALANCED LINE terminals.
ANT position 4 can be coax, single wire, or
balanced line. ANT 1, ANT 2, ANT 3 must
be coax only.
In both single wire and balanced line
systems, take special care to route the
transmission line as far away from the
station equipment as possible. Never drape
lines over the transmitter. These lines have
high voltage points inside the shack which
can produce strong RF fields.
Please note that 238C does NOT allow for
the connection of either coax-fed and
balanced line or single wire antennas to the
ANT 4 connection at the same time. There
is no switchable configuration for ANT 4 –
any antennas connected to these jacks will
be in use. If you have a coax fed antenna
and a balanced line or single wire antenna
connected to ANT 4 at the same time, both
of these antennas will be in use when ANT 4
is selected from the front panel.
