WEATHERPROOF ACTIVE ANTENNA FOR
10 KHz - 30 MHz RECEPTION

If you are a SWL or AM radio DX fan who would like better radio reception, do you have any of the following antenna and/or reception problems?
  • No outside antennas allowed
  • High RF noise level
  • No space for an antenna
  • You live in an apartment house
  • Theft and vandalism problems
  • You live in a bad neighborhood
  • You cannot erect antenna supports
  • Esthetics and unsightly appearances
  • Restrictive covenants
  • Fear of heights and climbing
  • Legal liability - kids, pets, etc
  • Possibility of severe weather
  • Fear of lightning strikes
  • You live in a mobile home
  • Cannot afford an elaborate antenna
  • Need a second or temporary antenna
  • Operating several receivers from only one antenna
  • Your old SW receiver needs a boost

If you have some of these problems, this antenna may be of interest to you. This kit is a reasonable solution to all of the above problems. In the past, a shortwave listener would string an outdoor antenna up across the back yard, 50 or 100 feet long, maybe from house to garage, and excellent AM BC and shortwave reception would result. Today fewer people live in private houses with large back yards, and many live in large buildings or crowded developments. The ever increasing presence of more and more electromagnetic pollution inside many buildings make most AM or SW reception miserable for the apartment or condominium dweller. With only CATV and FM reception facilities, the AM and SW bands are totally ignored as no provision is made for AM reception. This kit addresses this situation with a novel approach. Several features of the antenna are:

  • Useable bandwidth 10 kHz-30 MHz covers all AM and SW frequencies, VLF to HF
  • Overall Length 50 to 150 cm (70 cm typical with preamp plus 60 cm pickup antenna wire)
  • Easily hidden, looks like a vent pipe or a garden stake, great for condos and homes in areas with restrictions forbidding outside antennas
  • Uses 50-75 ohm CATV style coax, Receiver impedance range 20-600 Ohms
  • Antenna preamp powered (24V DC) through coax feeder, no extra wires needed
  • Built in Isolation Balun for reducing noise pickup via coaxial cable shield
  • Preamp has electrostatic discharge protection, and RF Gain control
  • Can feed several AM or SW receivers simultaneously with no interaction
  • Can be coupled to AM receivers without an antenna input with a simple coupling loop, No direct connections neededMakes great master antenna system for AM radio and shortwave reception up to 30 MHz
  • DC block for separating DC power and RF signals, and power transformer for 120V AC included
  • Totally weatherproof when assembled as recommended, can be mounted in wet locations

The usual active antenna setups use a preamp mounted in a box that sits on top the SW receiver. The pickup antenna is mounted to the preamp, still indoors and still picking up noise. All you get is gain and if your receiver is a reasonably good one, even sometimes worse performance due to overload, intermod and noise. What you REALLY need is improved signal to noise ratio, not just more gain. This kit operates like a car radio antenna. Have you ever wondered how an AM car radio receives AM signals so well even in a hotbed of electrical noise such as a modern automobile? The secret is isolation from the noise source (ignition and electrical system), mounting the antenna on the outside of the the car body, and good impedance matching of the antenna to the receiver. This kit employs a low noise FET input preamp with better than 30 MHz bandwidth to match the very high impedance of a short pickup wire antenna to the low impedance (30 to 600 ohms) input found on most all SW receivers. The preamp is capable of delivering 2 volts RMS of signal into 50 ohms, more than you will ever receive unless you live next door to a high power broadcast station. This ensures freedom from intermodulation and cross modulation interference. The preamp is powered via the coax cable and can be mounted in a weatherproof housing, along with the pickup antenna wire. This housing is made of PVC electrical conduit or pipe. Plastic conduit or pipe is purchased by you locally so as to reduce shipping charges. Any home center, electrical, or larger hardware store carries this in stock, and it is very cheap. The antenna is made to a length of 12 to 48 inches as desired (suggested length = 24" for general use). The entire antenna assembly is weatherproofed and as it can be as small as 18 inches. The antenna may be mounted outdoors, outside the building in a hidden or disguised location. The building, especially if it is of steel or concrete construction, usually acts as a shield, attenuating internally produced electrical noise just as it attenuates desired RF signals. The antenna is very small and can be painted or hidden so as to disguise it. The coaxial cable (ordinary 75 ohm TV antenna cable) carries signal and also DC power for the preamp to the antenna. The cable is fed power from a DC block assembly mounted near the receiver, and is powered by a 12V AC wall transformer. Noise carried on the shield of the coax is reduced by a built in decoupling and isolation choke in the preamp

Performance is approximately equivalent to what you would get with a 25 to 50 foot outside wire antenna mounted in the same location as the active antenna, assuming a 24 inch pickup wire. How well does it work? In our tests, the antenna was mounted on a plastic pipe in the ground, 2 feet above ground level, 100 feet in back of the house, and fed with a buried feeder system using common RG59/U TV coax run through half inch PVC electrical conduit for protection. Using a Drake SW8 portable receiver, many normally weak SW stations are well received, with lots of amateur band DX signals. On the AM Broadcast band daytime reception of stations 200 miles away in New York, Boston, and Montreal with good, listenable signals is the rule. And several European Longwave AM stations are regularly received during late fall, winter, and early spring seasons. These stations include Allouis, France on 162 KHz, Reykjavik, Iceland on 189 kHz, BBC Droitwich on 198 KHz, and Radio Luxembourg on 234 KHz, as well as German speaking stations on 171 and 180 KHz. These are generally heard with readable signals (S5) from about local sunset to well after 10:00 PM EST, in northeastern New York State. Equally good results are noted with an old AM tube type table radio, with no direct connection to the active antenna. In this case a coupling loop is used near the built in ferrite antenna on back of the radio. The antenna has been continuously powered for almost seven years, in good sunny 90 deg F weather, lightning storms, -20 F winter nights, ice and snow storms, and other assorted rotten weather New York State is blessed with. It has held up very well. Not bad for a 2 ft antenna!

With a simple modification, this antenna can be used with SW portable radios
Use with receivers having no separate external connector by means of a simple coupling loop
 
Active Antenna Kit with wall transformer (USA/Can 120V)
Price $72.95 USD
Active Antenna Kit without wall transformer (For Export use). 
Price $62.95 USD
Active Antenna Assembled and tested  (USA/Canada only)
Price $110.95 USD
Active Antenna for 12 - 24V DC ( Kit )
Price $67.95 USD
Active Antenna for 12 - 24V DC  ( Assembled )
Price $107.95 USD
Export Power Xfmr w / U.K. type 3 pin gnded plug,  240V                             Price $ 9.95 USD
Price does not include shipping and handling (See Order Form)
 
Kit includes all electrical components for preamp and DC block unit, and wall transformer for 120V AC operation. Cable and PVC pipe is not included with kits (purchase locally as required).   For export use, or where a 240V 50 Hz (or other voltage) transformer is needed, order the export version and obtain a suitable transformer locally.  12V or 24V DC negative ground operation possible with a separate modified DC Block unit.
Note that lead in and receiver cables are not included as these depend on installation Use standard CATV 75 ohm or RG58/U 50 ohm cable with CATV standard "F" connectors
 
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OTHER LINKS RELATED TO ACTIVE ANTENNA:
COUPLING LOOP      NOISE REDUCTION     VLF MODIFICATIONS
 
NORTH COUNTRY RADIO
PO Box 200, Hartford NY 12838-0200
EMAIL: support@northcountryradio.com
Tel 518-854-9280
Internet http://www.northcountryradio.com