AM Broadcast RFI Kits

Bullet Antenna End Fed Antenna Counterpoise Kit (41/71/92/111/155 Ft. Antenna Lengths)

SKU BULLET-CPK-41-20
$14.95
Wire Antenna Length
1
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Bullet Antenna End Fed Antenna Counterpoise Kit (41/71/92/111/155 Ft. Antenna Lengths)
Product Details
Brand: Palomar Enginees
UPC: Does not apply
MPN: BULLET-CPK
Type: NEW
Country/Region of Manufacture: USA

The “Bullet” End Fed Antenna Counterpoise Kit

Bullet 9U Antenna Counterpoises 08282022 png - AM Broadcast RFI Kits

Th kit contains 1 pre-assembled counterpoise wire which easily attaches to the counterpoise connector on the BULLET matching unit. Improves performance on 1 or more bands. Black/Gray/Blue wire is standard.

Application Note: This kit is typically used with only with Bullet Antenna systems like the 41 foot, 71 foot, 92 foot, 111 foot or 155 foot when you DO NOT USE the coax braid as the counterpoise (such as when you coax is too short). The counterpoise radiates just like the other half of a dipole so DO NOT GROUND IT! It is used to fine tune particular bands (by varying the length to get the lowest SWR reading on as many bands as possible. Multiple length counterpoises can also be used if needed for a particular band) if your particular antenna geometry doesn't show a low enough SWR on a particular band.

Suggested counterpoise lengths are as follows:

41 foot antenna wire needs a 16 foot length (20 feet of wire supplied so you can adjust as needed by folding back on itself)

71 foot antenna wire needs a 42-50 foot length (50 feet of wire supplied so you can adjust as needed by folding back on itself)

92 foot antenna wire needs a 90 foot length (100 feet of wire supplied so you can adjust as needed by folding back on itself)

111 foot antenna wire needs a 37 foot length (50 feet of wire supplied so you can adjust as needed by folding back on itself)

155 foot antenna wire needs a 95 foot length (100 feet of wire supplied so you can adjust as needed by folding back on itself)

When considering solutions for AM broadcast (550 Khz – 1.8 Mhz) you should consider Mix 77 ferrites available in a variety of shapes and sizes.  Choose a size to give the maximum number of turns of the affected wire or cable.

AM broadcast transmits on a low frequency with large antennas.  Consequently it takes a large antenna to receive the signals.  Typical “antennas” are AC house wiring, phone lines, long satellite or cable TV cables, DSL/CAT5 lines running between rooms, etc.  The device wires that connect to these  “antennas” need to be choked with as many turns through the ferrite as possible.  Some installation examples are shown below on this page.

For AC/ DC power cords and coax cables the F240-77 (2.4″ OD, 1.4″ ID) “Donut” toroid is the most popular.  Also available are smaller toroid donuts and Mix 77 beads. Shown below is a graph with 8, 10, and 12 turns through the toroid – obviously more turns has higher choking impedance.  Mix 77 toroid products are HERE and Mix 77 small beads (for small wires) are HERE

F240 77 Turns Comparison 1024x648 - AM Broadcast RFI Kits

F240-77 Turns Comparison from .1 – 8.1 Mhz

Shown below is a graph of frequency response verses choking magnitude for a F240-77 in the AM Broadcast band for a 12 turn coil around the toroid. (Same info as above but different frequency range).

AM Band Choking Graph F240 77 1024x648 - AM Broadcast RFI Kits

F240-77 Choking Impedance in AM Broadcast Band

 

 

Typical Installations for Donut/Ring Toroids

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AC Cable on F-240 Toroid – 6 turns

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Ethernet Cable on F-240 Toroid – 7 turns

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Audio or Mic cable on F240- 12 turns

 

 Extra Mix 75 Snap On Beads  HERE – VERY effective for AM Broadcast RFI