TX Techniques TX FM1, Technical Manual

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TX-FM1/S/R/A Technical Manual www.txtechniques.co.uk
5. Internal Adjustments
5.1 Carrier Frequency Setting
Select the desired carrier frequency on SW1,2,3 & 4 on “FM1-EXCI” PCB. For
example, to set the unit to operate on 98.4, turn SW1 to “0”, SW2 to “9”, SW3 to “8”
and SW4 to “4”. The new frequency will take effect when the unit is next powered-up.
5.2 Carrier Frequency (Fine Tuning)
Connect a frequency meter connected via the front panel “RF” BNC socket. Adjust
VC1 on “FM1-EXCI” PCB.
5.3 RF Output Power
With the front panel LCD set to display forward RF power, turn VR1 on “FM1-EXCI”
PCB to achieve the desired output power. To set the power accurately, use an
external calibrated RF power meter (with a suitable RF test load) connected to the
“ANTENNA” socket on the rear panel.
5.4 Audio Processor - Input Level
This board-level setting is factory set using a specific component value. R31 (right
audio channel) and R32 (left audio channel) on the “FM1-ALC” board determines the
overall level entering the multiband audio processor.
Decrease Normal Increase
1K5 (min) 2K2 4K7 (max)
Use of values other than the default values fitted during manufacture may result in a
deterioration of the broadcast sound quality.
5.5 Audio Processor - Individual Band Adjustments
These board-level settings are factory set, using specific component values. Values
below 47K or above 100K are not recommended. Use of values other than the
default values fitted during manufacture may result in a deterioration of the broadcast
sound quality.
80Hz LPF 200Hz BPF 650Hz BPF 2100Hz BPF 5000Hz HPF
R4 R6 R19 R20 R32
Increase Normal Decrease
Decrease value (47K min) 68K Increase value (100K max)
5.6 Audio Processor Overall Density Level
This board-level setting is factory set, during manufacture, using a specific
component value. R42 sets the overall density level. Use of values other than the
default value fitted during manufacture may result in a deterioration of the broadcast
sound quality.