Adjusting the Input Attenuation
The LT23S incorporates an
adjustable attenuator allowing for a 2m input drive up to a maximum of 10
Watts. To adjust to the available drive,
proceed as follows:
Remove
upper cover of the LT23S by (removing the four screws) and locate the control
for attenuation. This control is
labelled "P in" and is next to a pair of power resistors.
Turn
the control fully anti-clockwise, i.e.
towards ground potential. Connect up the
2m transceiver as normal. Connect the
output "1296 MHz out" to a well-matched dummy-load. If you have to connect a 23cm antenna as the
load instead, use a high-loss cable
(e.g. RG 58/U) in order to improve the match.
Now
switch the transceiver to transmit (FM or CW) and carefully turn the attenuator
control clockwise until the power meter of the LT23S shows 10 Watts. Don’t increase the drive power further as
this will only reduce the signal quality.
Due to the inertia of the meter,
the needle will usually show peaks of only 3 Watts on SSB, however the actual modulation peaks of the
LT23S will reach 10 Watts.
p5
© GJ Coyne & G Mussler Dec-2003