MEMBUAT DUMMY LOAD UNTUK PEMANCAR

 Oleh: Arif Johar Taufiq

A dummy load is a device used to simulate an electrical load, usually for testing purposes. In radio this device is also known as a dummy antenna or a radio frequency termination. It is a device used in place of an antenna to aid in testing a radio transmitter. It is substituted for the antenna while adjusting the transmitter, so that the transmitter does not interfere with other radio transmitters during the adjustments. If a transmitter is tested without a load, such as an antenna or a dummy load, the transmitter could be damaged. Also, if a transmitter is adjusted without a load, it will operate differently than with the load, and the adjustments may be incorrect.

The dummy load ordinarily should be a pure resistance; the amount of resistance should be the same as the impedance of the antenna or transmission line that is used with the transmitter (usually 50 Ω or 75 Ω). The radio energy that is absorbed by the dummy load is converted to heat. A dummy load must be chosen or designed to tolerate the amount of power that can be delivered by the transmitter.

The ideal dummy load provides a standing wave ratio (SWR) of 1:1 at the given impedance.

Saat kita membuat pemancar dibutuhkan dummy load untuk beban buatan sebagai ganti dari Antena, dan biasanya beban ini berimpedansi 50 ohm. Konfigurasi resistor 560 Ohm 2 Watt sebanyak 11 buah diparalel akan menjadi beban kira kira sebesar 50 ohm dengan kemampuan daya beban sampai 22 watt cukup untuk mensetting pemancar FM 12 W atau HT anda yang berdaya dibawah 22Watt.

Perhitungan:

1/Rtotal = 1/560 + 1/560... + 1/560 = 11/560

Gambar 1. Dummy 50 ohm 22 watt buatan sendiri