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.† Donít 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.
©† GJ Coyne & G Mussler† Dec-2003