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3 Results Found For "noise"
Unified Microsystems RAS-4 Receive Antenna Switch
Unified Microsystems RAS-4 Receive Antenna Switch is an outdoor capable remote relay unit that allows the operator to select up to four antennas. Receive only antennas are critical for success on the low bands. Due to the wavelengths of the low bands, these antennas cannot be rotated. Several very effective receive only antennas are mono-directional or bi-directional, including Beverage, Reversible Beverage, Beverage on the Ground (BOG), Reversible Beverage on the Ground (RBOG) and many others,. Therefore, a high quality, low noise four port receive antenna switch is required to cover all of the directions with multiple antennas. Common mode noise pick up can ruin the performance of receive antenna systems, so the RAS-4 isolates both the center conductor and shield of unselected ports. An internal bifilar ferrite choke further reduces common mode currents. This unit features female F connectors for RG6U coax with male F connectors, the standard field-serviceable coaxial cable assemblies for receive antenna systems. A very important requirement for dual feedline Reversible Beverage and RBOG antennas is provided by the RAS-4. By default, unselected ports are terminated for 75 ohms. The user can change to 50 ohm, open circuit, or center conductor-shield short by soldering wire jumpers. The RAS-4 is housed in a NEMA rated enclosure with a gasket lid. A cable gland seals the control cable entry. The internal circuit board has a conformal coating for additional protection. The RAS-4 can be mounted outdoors, with the enclosure flanges or with the included L bracket for mounting to a pole or post. The RAS-4 Receive Antenna Switch is a receive-only relay unit that cannot be used for transmitting antennas. The required in-shack control console switch is not included. The RAS-4 will work with a commercial or a simple home brewed, positive 12V One-of-Four switch. Choose from DX Engineering, EA4TX and others for manual or automated switching. Unified Microsystems RAS-4 Receive Antenna Switch Specifications Antenna Selection: 4 receive antennas to 1 main feedline Dimensions: Approx. 4.5 x 3.5 x 3.25 in. (11.4 x 8.9 x 8.3 cm), not including the bracket. Connector type: F (5 total) Unselected port termination: 75 ohm default; 50 ohm; open; shorted. Wire jumper selectable VSWR: < 1.5:1 from 100 kHz to 20 MHz Insertion loss: < 0.4dB from 100 kHz to 20 MHz Port to Port Isolation: > 45dB from 100 kHz to 20 MHz Control Cable: 3 wire plus ground (4 total conductors), Not included Switch Controller: 12 to 14 Vdc, Not included
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$124.95
United Microsystems BT-75/BOG Beverage-On-Ground Antenna Transformers
The United Microsystems BT-75/BOG Beverage-on-Ground (BOG) Antenna Transformers are specifically designed for Beverage-on-Ground receive antennas and is based on the proven BT-75 transformer used with elevated Beverage antennas. Because BOG antennas are installed directly on or just above the ground, they require no supports and can be significantly shorter than traditional Beverage antennas, making them a practical option where space is limited. BOG antennas typically exhibit lower impedance than elevated Beverage antennas. The BT-75/BOG is optimized to provide proper impedance matching between the antenna and 75-ohm RG-6 coaxial cable, improving performance compared to standard Beverage transformers. For correct operation, the far end of the antenna must be terminated with a 250 to 300-ohm resistive load. The United Microsystems RXT-270 termination resistor is recommended. Properly installed Beverage antennas are low-noise, receive-only antennas that provide excellent rejection of signals and noise from the undesired direction. Due to the lower velocity factor of radio waves near the ground, a BOG antenna can often deliver a radiation pattern similar to an elevated Beverage antenna of roughly twice the length, though with reduced signal strength. A BOG antenna as short as 150 to 200 feet can provide effective receive performance, although a preamplifier may be beneficial in some installations. The BT-75/BOG is designed for use with 75-ohm RG-6 coaxial cable. Originally developed for television applications, RG-6 offers low loss at VHF and UHF frequencies, resulting in extremely low loss on the 160, 80, and 40-meter bands. Its availability and low cost make it a popular choice for low-band receive antenna feed lines. The transformer is housed in a NEMA-rated enclosure with stainless steel hardware for long-term outdoor durability. A built-in gas discharge tube across the antenna terminals helps protect the transformer from nearby lightning-induced surges, although it will not provide protection against direct or very close lightning strikes.
Not Yet Reviewed
$37.95
Unified Microsystems Beverage Antenna Transformers
Unified Microsystems Beverage Antenna Transformers are now available. UMS transformers are built with stainless steel hardware and an F-Type coaxial connector. These transformers are fully enclosed for ultimate protection from the elements. They are corrosion resistant and sealed for many years of trouble-free use. Unified Microsystems Beverage transformers should be used with 75 ohm cable, typically RG-6, 6UF, F-6, or equivalent. H. H. Beverage described his "Wave Antenna" (the first Beverage) in the November, 1922 QST Magazine. Beverages are classic designs with well-defined characteristics and time-proven performance. Beverage antennas are among the simplest of high signal-to-noise-ratio antennas to construct. Make Unified Microsystems Beverage Antenna Transformers part of your receive-antenna system. Get yours from DX Engineering today!
( 10 )
$37.95