COM port radio extender. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Computers
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TRANSMITTER it does not differ in originality and is built according to a scheme with quartz stabilization and frequency multiplication. The master oscillator is excited at the 5-7th harmonic, followed by a frequency tripler, then an amplifier-modulator and a frequency doubler with a load L4. The first 4 stages are separated by a screen and assembled on a printed circuit board according to [1].
The quartz resonator is selected on the basis of Fkv \u1d Fiz / n2 / n4 / n1, where n3,5,7,9 is the number of the harmonic on which the resonator is excited (2), n3 \u2d 4 or 2 (second stage), nXNUMX \uXNUMXd XNUMX (fourth cascade).
Fig.1 (click to enlarge)
Two (three) cascade power amplifier depending on the required communication range. Combined installation: pads for the outputs of transistors and trimmer capacitors 4x4mm in size. engraved on the surface of foil fiberglass, which serves as a carrier substrate. Chokes are similar [2].
L1 - 6 turns on a frame with a diameter of 5 mm with a trimmer.
L2,L3 - 3,5 turns without a frame with a diameter of 4 mm with a silver-plated wire.
The design of coils L4, L5 and L6 is shown in Fig. 2.
Ris.2
The setting is well described in [1, 2]. The output circuit is tuned to the standard antenna according to the readings of any microwave probe.
RECEIVER - conventional TV with UHF range. The signal is taken from the output of the SMRK with a constant component (Fig. 3). The comparator is also not difficult, the output is connected to the RXD COM port.
Ris.3
ANTENNAS spiral, diameter is calculated as wavelength/3.14, about 10 turns of copper wire are laid as evenly as possible on a cardboard frame in a wavelength. The frame is glued to an aluminum or copper screen one and a half times the diameter of the antenna. The transmitter is located on the back of the screen directly at the "hot" output of the coil.
In conclusion, please do not judge strictly for the amateurish approach. The device was created to achieve results as soon as possible at minimal cost. At the same time, I will be grateful for sensible suggestions that improve or simplify the product.
This thing is more than 2 years old, IP connection catches errors. Tested with director antennas. It is better to tune the antenna to the transmitter using the field detector, and then do the same for the receiver.
Literature
1. A. Ermak, G. Churin. Radio No. 2 1989, p.28.
2. V. Prokofiev. Radio No. 2 1983, p.18
Author: Mardaryev E.A.; Publication: N. Bolshakov, rf.atnn.ru
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