Brought to you by PCS Electronics, www.pcs-electronics.com
44
Appendix C: Adding an amplifier – complete fm transmitter
block by block
Now that you’ve connected stereo encoder and already have nice stereo sound, it may be time to increase your power
output. How about adding an external amplifier? Some of you will say, sure, but will the nice power/swr meter built into
MAX PRO 50xx+ know how to measure power with this amplifier added and will it show it properly on the LCD display?
The good news is that we have a solution for this. Not only does the MAX PRO 50xx+ have ability to read power/swr with
external amplifier installed, it can also read amplifier temperature and amplifier supply voltage. To top this off, swr and
temperature protection still works just like before.
Fig. 21: Connecting an external amplifier module – Complete FM transmitter, block diagram
Diagram above explains the entire FM transmitter system, with mains power supply (1), DCDC converter (2), stereo
encoder (3), FM exciter (4), FM amplifier pallet (5), output filter (6), ControlMini board (7), interconnect system (8 &9) and
cooling fans. I will briefly explain each of the above subsystems:
1.) MAINS POWER SUPPLY: Provides power for the entire transmitter. Usually accepts mains voltage, from 110 to 240V,
and outputs 24 or 48V DC. Exact power rating depends on the power consumption of the entire transmitter. A 300W
transmitter usually consumes around 500W of power. A 1000W transmitter typically consumes around 1500W of power. An
engineer should also consider safety margin and use a power supply that can provide 20-30% more power than needed.
Voltage rating for mains power supply depends primarily on the type of amplifier used. Most pallets accept 24-28 or 48-50V.
You can find all kinds of mains power supplies here at our website:
http://www.pcs-electronics.com/transmitter-accesories-mains-power-supply-c-71_74.html
Appendix
C
