Equivalent load visually for QRPP-transmitter

Our little article about miniature incandescent lamps used in Christmas lights. Having examined spoiled garland and bulbs vypayat of it, I found their nominal voltage (6.3 V) and current consumption (0.1 A). A simple calculation shows that the resistance of the filament lamp (R) is:

R = U / I = 6,3 / 0,1 = 63 (ohms)

As is known, the resistance of the filament and is dependent on the temperature to which it is warmed. Partial nedokale can assume that the resistance of a light bulb is about 50 ohms — standard value impedance interconnect links in radio, antennas and feeders etc.

The portable compact equipment class, which includes QRPP-transmitters used small-sized RF connectors. The mating connector (eg, connector) can mount a light bulb. The bulb is soldered one end to the center conductor of the coaxial connector (eg type SMA), the second — his body and allows you to visually monitor the output power of the transmitter, or helps to set its output stage.

Power bulb low — only 0.63 W, however, when a small overtempered allows to adjust the transmitter output power up to 1 Watt. Most importantly, the light begins to shine noticeably already at 100 MW, while playing the role of the equivalent load and display output with visual inspection.

If necessary, increase the dose equivalent can be achieved by including 4 light bulbs (two branches of two series-connected light bulbs connected in parallel), the good, the size of small light bulbs, and the equivalent load will rather small-sized. And yet, in a lot of the same garland lights that will make more than one equivalent, but still remain in reserve …

Victor Besedin, UA9LAQ.

Like this post? Please share to your friends: