* Complete package - just add coax * works single band with ease * can be configured as vertical or inverted L configuration * Choice of 1.5K, or 5KW PEP rated choke to suit power needs After many requests we have created a compact, special interface box with internal feed line choke and separate connections for counterpoises (not grounded) and ground connection. The 1:1 choke keeps RF current off the outside of the coax braid and on the antenna where it belongs. The extra choking action also means that the coax feed line will not act as a radiator causing unnecessary RF interference (RFI). 80 M radiator/counterpoise is 70 Feet (you get 1 each) - adjust length to your favorite frequency 160 M radiator/counterpoise is 130 Feet (you get 1 each) - adjust length to your favorite frequency Antenna is tuned to you favorite frequency by shortening the counterpoise (roll it up or cur length) while keeping the radiator length constant. Choose 1,5KW PEP or 5KW PEP options. 1.5KW and 5KW are in 4" x 4" x 2" enclosure. 1.5KW is 3 pounds, 5KW is 5 pounds. 2 antenna insulators are included. ADD CMNF-1500 (1.5KW) or CMNF-5000 (5KW) common mode noise filter at radio end of coax to reduce common mode noise up to 6 "S" units on long coax runs!
Inverted L antenna with radiator and counterpoise for simple installation - choose 80/160 meters and 1.5KW/5KW feed line choke included inside weatherproof enclosure. Separate counterpoise and ground connections
$79.95
For RFI common mode suppression use, mix 31 is effective from 1-300 Mhz, mix 43 works from 25-300 Mhz, Mix 61 is for 200-2000 Mhz, and mix 77 favors .1-50 MHz. These frequencies are those of the interfering signal to be eliminated, not the operating frequencies of the equipment to be protected. See Mix Selection for other applications.
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Bead dimensions are shown in the picture below and in the table as A, B, C
Ferrite Bead Dimensions
Application Note: Use impedances for each bead at your desired frequency to select number of beads needed for desired Z. For example if you have a 50 ohm RG-8 coax cable and want a choking impedance of 500 ohms at 10 Mhz, you can check the FB102 column (since FB102 will pass RG-8 through its center ID) at 10Mhz and find that Mix 31 has a Z of 108 ohms/bead and Mix 43 has a Z of 91 ohms/bead. For 500 ohms we would need 5 mix 31 beads or 6 mix 43 beads to have greater than 500 ohms. Mix 31 has better response below 10 Mhz but above 10 Mhz mix 31 and mix 43 are very close. If you need more Z, just use more beads in series on the cable or use more windings thru a larger ID bead (e.g. USE FB102-31 for 4 turns of RG-8X for 16X increase in Z per bead – see pictures below for examples). Use Mix 61 for VHF and above for RFI/EMI suppression and below 30 Mhz for multi-ratio impedance transformers (baluns/ununs). See Mix Selection for other applications.
For extra large cables use the FB400-31 which has an inside diameter of 3 inches (76mm).
Frequency Range Comparison Chart
(FB56-xx size)
Multi-turn Common Mode Choking Impedance Increase Example (FB56-43)
Ferrite Bead relative size comparison
Left to right sizes: FB56 (ID = .25″), FB102 (ID=.505″), FB103 (ID=.77″)
SLIP ON Sizes for Heliax and Coax Cable
Cascaded Common Mode Chokes/Line Isolators/1:1 Baluns
 RG58 4 turns on 2 FB102-31 for 2000 ohms choking impedance |
 RG58 12 turns on FT240-43 for 4000-6000 ohms choking impedance |
Handy Wire Size reference for ferrite bead sizes needed
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Connector already on cable? See Snap On Ferrite Beads for convenient installation on cables with connector already installed.