Do You Have RF Getting Back Into The Shack?

Do You Get Bad Audio Reports Because Of RF Getting Into Your Mic?

Does Your Rig Act Strange When You Increase Your Transmitter Power?

Do You Get "Bit" By Your Mic When Keying The Rig?

Then CHOKE-KIT!

CHOKE-KIT! is a simple and effective way to reduce or eliminate unwanted RF from being conducted back into the shack when installed either near the antenna feedpoint or near the rig, or both.  CHOKE-KIT! is a quality pre-assembled high power current balun* which provides approximately 24 microhenries of "common-mode" inductive reactance. 

"Common-mode" means CHOKE-KIT! will only attenuate or" choke" unwanted RF power present on the coaxial feedline and not affect the RF power you want to deliver to the antenna.  It is perfect for dipoles, G5RV's, loops and other installations where the unbalanced coaxial feedline interfaces with the balanced portion of the antenna.  It will also reduce RF introduced on the feedline due to close proximity to other radiating sources such as power line noise or other adjacent HF transmitting antennas.

Using a Line Isolator in series with the antenna’s feed system can substantially improve the antenna’s front-to-back and front-to-side ratios. It does this by providing the antenna with balanced current at the feedpoint and by very effectively preventing the feedline from acting as part of the antenna. The addition of a Line Isolator or a proper balun can significantly reduce feedline radiation and dramatically decrease RFI and TVI. Beam antennas, especially, benefit from improved balanced drive and superior feedline isolation, but even simple dipoles benefit from properly selected and installed baluns and Line Isolators. Receiver noise also may be reduced by eliminating signal pick-up by the feedline.

Applications include:

• Feeding dipoles, loops, or other similarly balanced antennas with unbalanced feedlines (coax).
• Reducing unwanted RF due to feedline proximity to antenna elements (low height dipoles, etc).
• Reducing man-made noise (computers, lamp dimmers, etc) conducted from the shack to the antenna by the feedline.
• Great for emergency "Go" kits when deploying less-than-optimal antenna installations (no counterpoises, poor grounding).

The secret behind CHOKE-KIT! is the premium ferrite material, which will not saturate under high power and high VSWR. Five ferrite cores provide inductance equal to over 28 feet of RG-8 coax wound in a nine-turn coil.  This means less wind loading when used at the antenna feedpoint and less clutter when used at the rig.  CHOKE-KIT! will not couple RF into other nearby objects when properly installed. 

The use of high performance materials allows CHOKE-KIT! to provide reasonable attenuation of unwanted RF on coaxial feedlines well into the VHF bands with a minimum of power loss.

Every effort has been made to ensure years of trouble free operation, however there are a couple things to remember:

• Be sure to use adequate coaxial waterproofing sealant when using outdoors.  UHF connectors are not waterproof by themselves.
• Do not drop on a hard surface.  The ferrite cores are like any other ceramic material and will crack if handled roughly.
• Do not use this device to support wire or cable weighing in excess of 10 pounds without a strain relief or the connectors may pull off the cable.
• If you want a CHOKE-KIT! with more inductance (more ferrite cores), or with "N" type connectors, or if you want to purchase the cores separately for DC power line filtering and other uses, please ask.

Specifications

Frequency:  1.8 - 300 MHz

Through-line impedance:  50-ohms (nominal)

Insertion loss: less than 0.2 dB at 60 MHz

Common mode inductance: 24 uH (nominal) – 24 microhenries provides an inductive impedance of 270 ohms at a frequency of 1.8 MHz.

Power handling: 3kW continuous duty

Load mismatch tolerance:  greater than 5:1 VSWR at 2kw

Connectors:  PL-259 (2x) + barrel

Ferrite material:  31 Mix

5KW SSB rated

Specifications subject to change without notice.