Portable and Mobile Radio RFI Solutions
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 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:
- Generator RFI Kit (Part # RFI-GEN) with FSB31-1 ferrite filters at each end + Nylon ties for security
- Transceiver RFI Kit (Part # RFI-XCVR)
- Laptop RFI Kit (Part # RFI-1C)
- Coax Cable Noise Filter (Part # CMNF-1)
- Bullet-55 portable HF end fed antenna system
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Coax Inline Common Mode Choke Unun - 500 Watts 25-300 MHz- 10, 11, 6, 4, 2 MetersCoax Inline Common Mode Choke Unun - 500 Watts 25-300 MHz- 10, 11, 6, 4, 2 MetersSKU FC-8X-3-31List price $39.95 Save 30%$27.95On Sale
Laptop Computer with DC power RFI Kit - 7 FiltersLaptop Computer with DC power RFI Kit - 7 FiltersSKU RFI-LaptopList price $34.95 Save 14%$29.95
MAXI-CHOKER Coax Line Isolator/Balun, 1-61 MHz, 1.5/3KW, SO-239 In/Stud Output, FLAGPOLE OCF, G5RV, ZS6BKW, BN4000 Replacement, Ladder Line-Coax interfaceMAXI-CHOKER Coax Line Isolator/Balun, 1-61 MHz, 1.5/3KW, SO-239 In/Stud Output, FLAGPOLE OCF, G5RV, ZS6BKW, BN4000 Replacement, Ladder Line-Coax interfaceSKU MC-1-1500LL$89.95
MINI-BALUN 1:1 Coax Interface to Ladder Line, Dipole elements, 500 Watts PEP, up to -38Db Common Mode Rejection, 1-61 MHz, Flagpole, Dipole, Beam and G5RV/ZS6BKW AntennasMINI-BALUN 1:1 Coax Interface to Ladder Line, Dipole elements, 500 Watts PEP, up to -38Db Common Mode Rejection, 1-61 MHz, Flagpole, Dipole, Beam and G5RV/ZS6BKW AntennasSKU MB-1-500SS$69.95
VHF/UHF Generic Base Transceiver RFI KitVHF/UHF Generic Base Transceiver RFI KitSKU RFI-VHF-BASE$49.95
HF 1-61 MHz coax feed line common mode chokes
Portable and Mobile Radio RFI Solutions
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 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:
- Generator RFI Kit (Part # RFI-GEN) with FSB31-1 ferrite filters at each end + Nylon ties for security
- Transceiver RFI Kit (Part # RFI-XCVR)
- Laptop RFI Kit (Part # RFI-1C)
- Coax Cable Noise Filter (Part # CMNF-1)
- Bullet-55 portable HF end fed antenna system
1:1 feed line Chokes (also known as feed line current chokes, common mode chokes, line isolators, current mode chokes, and 1:1 baluns/ununs) are available in kit form or assembled form in a weatherproof Current Unun and Balun Enclosure which we call a CUBE™. All 1:1 chokes are ferrite based and are designed for 50 ohm coaxial cable input and 50 ohm output. 1:1 Ferrite toroidal or bead chokes have a higher choking impedance than our popular Sleeve Chokes and various models are available for specific frequency ranges and power levels.
1:1 Chokes are useful for choking common mode currents that may flow on the exterior of the coax cable shield while allowing the signals on the interior of the shield and the center conductor to flow unaffected and keeping the common mode current on the antenna. They isolate the coax shield and prevent it from becoming part of the antenna system.
1:1 Chokes are useful between balanced lines for center fed dipoles at their fundamental frequency (468/f (MHz), beam antennas with a 50 ohm balanced driven element, G5RV, loops, yagis, NVIS antennas, mobile installations, portable antennas and anywhere common mode current (or RFI) is a problem. They are also helpful between transmitter and linear amplifier or between linear amp and antenna tuner or as isolation chokes where higher choking impedance is needed (in the range of 2K-7K ohms).
1:1 Chokes are also very useful as feed line current chokes at the “radio end” of the antenna (we call them coax noise filters) where they choke/filter common mode current induced onto the coax shield from radiated waves (from your antenna, and other sources such as DSL routers, computer devices, plasma TVs, etc. originating in your house or your neighbor’s house). For RFI issues see RFI/EMI Solutions for general use or for specific radios and devices.
For best results we recommend a 1:1 choke at the “antenna end” of the coax and a coax noise filter at the “radio end” of the coax. (A side benefit is a reduction in noise level caused by common mode currents). 1:1 chokes are also available as Sleeve Chokes (Slip on or Snap on) for ease of installation and light weight on the antenna.