12:1 Baluns/Ununs

Portable operation is fun but also brings challenges to the radio operator concerning receiver “noise” levels, RF interference from adjacent sources including close by transmitting stations, and RFI from portable generators. A typical scenario and some suggested Palomar product solutions are shown in the picture.

Portable Operation RFi Reduction Picture png - 12:1 Baluns/Ununs

Portable operation is typical of ham radio operating events such as Field Day, Summits on the Air, Route 66 events, National Parks on the Air, California QSO party, DXpeditions, and emergency operation command posts, etc.

Suggestions

Each low power operating station with a generator should have:

  1. Generator RFI Kit (Part # RFI-GEN) with FSB31-1 ferrite filters at each end + Nylon ties for security
  2. Transceiver RFI Kit (Part # RFI-XCVR)
  3. Laptop RFI Kit (Part # RFI-1C)
  4. Coax Cable Noise Filter (Part # CMNF-1)
  5. Bullet-55 portable HF end fed antenna system


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12:1 Baluns are useful between 600-650 ohm balanced loads the impedance at the  end of the feed line is 600 ohms (1/2 wavelength feed line), or high impedance feeds for rhombic,  T2FD and traveling wave antennas.

12:1 Ununs are useful between coax and long wires with a load impedance near 600 ohms like a beverage antenna.  Shortwave listener antennas also can benefit with the 12:1 unun and it may provide a better match than 9:1 ununs – this means quieter noise levels and stronger signals so you can hear distance stations easier.