Silent antenna tuning. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Antennas. Measurements, setup and matching
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When working on the air on transceivers with a transistor output stage, radio amateurs usually use matching devices that require significant power emitted on the air at the time of tuning to tune to the minimum SWR, which is not very good and convenient. The level of the signal emitted into the air according to the proposed method [1] does not exceed 10-12 W.
Figure 1 shows a diagram of a directional coupler. The matching device connected to it is tuned to a minimum of noise in the receiver.
Ris.1
Transformer T1 is made on a ferrite ring K7...12 with a permeability of 20...50. The number of turns is 10, the branch is from the first turn, the winding is in the 270° sector. K1 - antenna relay in the transceiver.
The directional coupler loss (0,5 dB) is negligible. Resistor R (15 ohms) is balanced by a minimum of noise with a matching device pre-configured in the traditional way.
Figure 2 shows a diagram of the noise generator.
Fig. 2
Almost any noise generator can be used. The use of "tonalnik" is desirable. With some skill, working with such a device is very convenient, especially for visually impaired people.
Literature
- Radio, 1981, N10, p.57.
- Handbook-94, pp.26-5.
Author: A.Kuzmenko (RV4LK); Publication: N. Bolshakov, rf.atnn.ru
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