VLF – ( SID) AMPLIFIED LOOP ANTENNA : MODEL “A”
TOP PHOTO : –( Front ) Shows – Gain Control ( red knob ) – On off bypass switch – Red Operating ( ON ) Led.
BOTTOM PHOTO – ( Back ) Shows – Power – Battery Charging Jack & BNC Antenna Connector.
GENERAL SPECIFICATIONS : FEATURES
GAIN:
VLF Signal Gain ( pre-amp –on )* – ( Reference –50 dBm output level with switch in “ OFF “ bypass mode )
10 KHz -31.6 dBm 65 KHz – 20.6 dBm
15 KHz- 33.3 dBm 70 KHz - 18.9 dBm
20 KHz -33.9 dBm 75 KHz - 17.0 dBm
24 KHz -33.4 dBm 80 KHz - 15.5 dBm
25 KHz -33.4 dBm 85 KHz - 15.5 dBm
30 KHz -32.3 dBm 90 KHz - 12.3 dBm
35 KHz- 30.8 dBm 95 KHz - 10.1 dBm
40 KHz –29.2 dBm 100 KHz - 6.9 dBm
45 KHz –27.4 dBm
50 KHz - 25.6 dBm
60 KHz - 22.3 dBm * Gain control fully open
Frequency Range – 10 KHz to 100 KHz
Gain – Adjustable (with side mounted potentiometer on enclosure) 0 to 31 dBm
Input - Impedance – 50 to 75 ohms
Output Jack – BNC
Power draw – 0.6 mA – typical
Maximum Battery Charge Current ( fully discharged battery ) – 6mA.
Note : Battery LED will not light up when charging a fully discharged battery:
Typical trickle charge current ( fully charged battery ) - less than 0.8 mA.
Battery Type – 9 volt NiMH –rechargeable
External Power Supply TO Charge Battery –117-240 VAC wall plug transformer – output - 12vdc. 500 mA. Input jack is reverse polarity protected. Fully regulated- UL & CUL recognized. Can be used worldwide.
Noise Rejection – Loop is electrostatically shielded for maximum noise rejection.
PVC Tube – UV Stabilized . PVC enclosure has heavy duty rubber gasket on top lid – ss screws.
Options – External Solar panel for battery charging. Directional compass installed on top of enclosure .
Dimensions : Control box – 4 “W X 4”D X 4.5 “ H
Loop : 15 “ wide X 15 “ high ( 15 “ square )
Construction– All PVC tube & fittings are waterproof : Ends of loop going through PVC enclosure are sealed with rubber o – rings. Internal electronics, transformer, filters, & pre-amp board ( with the exceptionof the battery,gain control, switch & LED ) are encapsulated in epoxy. . Switch ,gain control & LED are sealed to outside of the enclosure with silicone sealant.
Outdoor Installation ( Building an inexpensive RADOME )
The loop antenna may be placed outdoors – simply cut out a piece of marine plywood for the base . Use a larger piece that can support bricks on 2 ends..Screw the antenna to the base using the attached bottom lugs on the enclosure. Use stainless steel screws. Place a large plastic weatherproof utility can over the antenna.Seal the bottom lip with silicone sealant. Secure the can to the base , ( DO NOT USE A METALCAN ) The can will act as a shield preventing signals from reaching the loop antenna. Drill two weep holes on each side of the can for air circulation. Place two bricks on each end of the base to prevent wind gusts from tipping over the covered loop. It is also a good idea to mark the outside of the plastic can “ “WARNING ! DO NOT MOVE. ANTENNA INSIDE “
For pricing, delivery, & availability contact : Carl M.Chernan WA3UER e-mail