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?
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.
- 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.
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.
Works as advertised. Mounted per recommendations on a random wire in coax runand is working fine. Purchased another for field work. Prompt delivery.
Made well and works great.
Prior to purchasing this item I emailed the company to ask questions and in short order I received a reply. With my questions answered I placed my order and received my order promptly. The quality of build of this choke looks to be very rugged and I believe that it will hold up forever. I have an upcoming use for another and will not hesitate to order again.
Own three, great product solved my problems also own two OCF multi banders will always buy from NI4L. 73's
Great product t and better than the MFJ-915, as this one covers the 6 meters band too. Excellent product and working fine.
Works fantastic! Great quality and fitment.
Very well.made. I am using it on an OFC dipole between the bslum and the feeling line. No RF reflected.
Well built and no loss noticed
It worked well to reduce the RF in my shack. It seem to have even increased my signal strength according to reports I've received.. 73, Tim WB8HRO
I had a real issue with RF in the shack, grounding, changing out coax for better coax didn't help. But when i purchased the Line Isolator and installed it below my Windom antenna, all the RF was gone from the shack. I highly recommend using it..
I had recently purchased a new hf rig, i knew i had some RF in the shack, however when i could not operator the Rig because of rf, i had to fix the problem. I purchased the Line isolator from Chris, put it between the line out of my 3kw tuner and my feed line out and absolutely 0 rf in the shack now. Great product.
Excellent quality, great customer service and quick delivery.
It is very sturdy and is a very effective addition to the antennas performance
worked as needed, fast delivery.