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
50 ohm coax to 75 ohm balanced output baluns are useful for low (< 1 wavelength) dipoles exhibiting 75 ohm characteristic impedance or for matching to balanced ladder line whose endpoint impedance is near 75 ohms.
50 ohm coax to 75 ohm CATV coax connections are easily done with a 1.5:1 unun with SO-239 connectors on input and output. Likewise 50 ohm coax to unbalanced verticals or loads near 75 ohms can be matched with a 1.5:1 unun.