Questions tagged [choke-balun]
The choke-balun tag has no usage guidance.
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End fed long wire antenna causing issues
I use a hex beam to operate from 20 meters to 6 meters with amazing results.
I wish to operate 40 meters and 80 meters also, and can only really install an end fed long wire due to my installation ...
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Can I convert an inline 1:1 CMC into a balun feed for a dipole?
I built my first 1:1 CMC transformer recently using 100 ohm CAT5e pairs in parallel. I used an FT-114-43 with 9 turns on each side and squeezed it into a small box with female coax connectors. I plan ...
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How much attenuation (dB) from a balun is expected?
I'm building a dipole antenna for 433 MHz, first one ever. I will have to use a ferrite bead to balance the feed. How many decibels of attenuation should I expect from the ferrite bead?
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Common-mode choke (CMC) hurting my SWR. Live with it? Drop the choke?
I have been using a Par EndFedz Mk2 Trail Friendly 40/20/10 though using the matchbox from an EndFedz EF-QUAD (with Vibroplex’s blessing) so I could transmit at more than 25W. On all three bands I ...
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There are good guides for building 1:1 current baluns. What about 4:1?
Some dedicated hams have spent a lot of effort gathering empirical data on various constructions for common-mode chokes. For example, G3TXQ's work is commonly referenced, and K9YC's is pretty well-...
- 555
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How do you calculate the number of turns for a common mode choke?
I want to build a common mode choke for my end-fed wire antenna, using turns of coax through an FT140 or FT240 ferrite. I can find various finished products for sale, but I want to make my own. I ...
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J Pole, what is the best way to deal with Common Mode Current? [duplicate]
I am planning on utilising a ferrite choke on a J Pole antenna for CMC. Placement directly on the feedpoint poses possible mechanical restraints. Is it okay to place it a quarter wave down the coaxial ...
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Do chokes at the antenna feedpoint stop the coax from receiving signals as well, or just transmitting?
It seems common knowledge that a choke at the antenna feedpoint stops the outside of the coax shield from radiating when transmitting into the antenna. But what about stopping the outside of the coax ...
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When would we ever want to use a voltage balun in ham radio?
In a world where common mode current is the enemy, and we're constantly doing what we can to avoid RF in the shack, why would we ever choose a voltage type balun over a current balun?
I understand ...
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Importance of Ferrite Size in Coax Choke Balun
The question is quite simple: When making a coax choke balun, does the size of the ferrite matter, and if so, why?
I have seen design notes that say to use a single FT240-43 toroid for powers up to ...
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Why do amateur radio operators call an RF choke a balun?
When using a balanced antenna such as a half wave dipole, with an unbalanced feed line such as coax, an RF choke can be used to block RF current emitted by the transmitter from splitting up at the ...
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Rotatable Dipole & RF Choke
I have a Diamond HFV-5 (rotatable dipole) in the attic fed by ~30ft of coax. The antenna system comes with a Balun at the feedpoint. Would it be worthwhile to add an inline RF Choke (Unun) in addition ...
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Dipole increased CM current using choke balun
My 20 meter inverted vee dipole is fed with 56 feet of 50-ohm coax. The SWR measures 1.2 at the center of the band. According to http://arrl.org/grounding a balanced antenna doesn't need a ground, so ...
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Voltage vs. Current Balun for Dipole
I'm a new radio amateur setting up a half-wave 10-meter inverted vee antenna fed by 50 ohm coax. I understand that the inverted vee lowers the normal 72 ohm dipole closer to 50 ohms, so I only need to ...
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Can I use a 1:1 current balun to feed a 1/4λ vertical?
I have an LDG RBA-1:1 current balun, and I was wondering if it behaves as a common-mode choke that I can use for a ground-mounted quarter wave vertical w/ 16 radials.
The other choice I have is a 4:...
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Coax or bifilar windings for a choke?
Making a common mode choke out of bifilar windings has proven rather difficult. For me the difficulty lies in getting the impedance to remain a constant 50 ohms from on the HF bands. I've tried 14 ...
- 781
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Magnetic Loop Antenna with RFI Choke
Because of space limitations, am purchasing a magnetic loop antenna. Because of needing to move the antenna around, do i need a RFI choke in the feed line?
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How to determine number of turns for a 1:1 balun?
I would like to make a 1:1 balun with М1000НМ ferrite core (magnetic permeability - 1000) and 1 mm thick copper wire using triple bifilar winding. Unfortunately I didn't manage to find a clear ...
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Is this the Correct Ferrite Core to Reduce RFI as a Common Mode Choke?
I have a Flex 3000 connected via RG-11 coax to a inverted V fan dipole tuned for 40m and 20m on my roof. I have an "ugly" balun up on the mast by the antenna. I further have the feed-line going into a ...
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Choke at feed point of delta loop with Q match
I am working on putting together a 40 meter delta loop using a 1/4 wavelength of RG-6 as the matching section. However I'm unsure of where to create my feedpoint choke.
Do I coil up the RG6 right at ...
- 781
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G5RV Jr. fed with ladder line and coax
I am a new ham and I was just given a G5RV Jr. I have about 20 feet of coax plus about 60 feet of 450 ohm ladder line I can feed it with. Can I extend the G5RV Jr. feed line with the ladder line I ...
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Why do we distinguish between balanced and unbalanced?
I hear all the time, "you need a balun between your balanced dipole and unbalanced coax to stop the common-mode current" when it seems the proper advice is "you need something to stop common-mode ...
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What is the maximum number of turns in a ferrite core used as a common mode choke?
Is there a way to estimate the maximum number of turns which can be used with a ferrite core used as a common mode choke?
It is known that the impedance of such a choke is proportional to the square ...
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What core material do I need to construct a 1:1 unun for 6M?
I want to build a 1:1 unun for a 6M dipole. Power level 100W. What core material should I use?
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Do end-fed dipole antennas need choke baluns?
I have a couple of end-fed wire antennas I bought that came with matching baluns. One has a 9:1 unun, and I'm not sure about the other one. In addition to those, should I also put a choke balun on the ...
