ANTENTOP- 02- 2003, # 003

Trap in the Main

Trap design

and to do tuning to the maximum of RF-voltage across the trap.

If RF voltage is leaking to the main at other amateur ranges, traps in main's wire must be installed for each of these ranges. The basic requests for the traps are the traps must have as possible high Q-factor and the traps must be shielded from each other. Distance between a screen and coils should be not less half of diameter of the coil. Table 1 shows data for trap intended for amateur ranges from 160 up to 10 meters. Air dielectric variable capacitor of 10 -100-pF is used for tuning the traps.

Figure 4 shows schematic and construction for symmetrical retuning main filter. You may try to do the filter if you have leaking of RF energy to the main at several amateur bands. Data for coils takes from Table 1. The filter is tuned or by a LED (see Figure 1) or by a RF- voltmeter.

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