Simple Balun CircuitĪn good old ferrite rod from your junked radio receiver could be applied to build an antenna balun as demonstrated.
This is actually the technique of supplying dc power to a preamplifier employing simply the RF coax cable. The HF/SW receiver preamplifier is consists of a broadband toroidal transformer (L1~a and L1-b), LC network (made up of a 1600-kHz, high-pass filter and a 32-MHZ, low-pass filter), L2 and 元 (26 turns of #26 enameled wire wound on an Amidon Associates T-50-2, red, toroidal core), a couple of resistive attenuators (ATTN1 and ATTN2), and a MAR-X device.ĭemonstrated in this article could be the composition of a simple 1-dB pi-network resistor antenuator. This wideband antenna preamplifier features a gain of about 20 dB via 40 to 860 MHZ, covering the complete VHF, FM, commercial, and UHF bands.Ī phantom power supply delivers dc towards the pre amp through the coaxial cable feeding the unit. VLF 60-kHz Antenna/PreampĪppropriate for 60-kHz common frequency reception, listed here is a schematic for any FET preamp and antenna. The circuit is powered by way of the coaxial cable employed to hook up the antenna to a receiver. T1, a double gate MOSFET, delivers lower sound, high-input impedance, and high gain. VLF/VHF Wideband Low-Noise Active Antenna CircuitĪ 30- to 50-cm Whip antenna supplies reception through 10 kHz to around 220 MHZ. Will not transmit with this particular antenna-it is made for receiving only. Q1 and Q2 are configured as a preamplifier for the loop antenna. L1 is two turns and L2 is one turn, threaded with the loop.
This antenna circuit may help to lessen power line noise‘ A plastic “hula hoop” or conduit 3 feet in diameter, coated along with aluminum foil like a shield can be used for L1 and L2. Dual-Band Loop Antenna For 80 And 160 m Circuit
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