COAX CHOKE

[W5LZ]

VE3XE,
A form with carbon in it will 'cancel' the affect of an coaxial choke? Oh, I don't think so. In fact, it would enhance it's inductive reactance, make it more effective. It won't make a very significant difference either way in practice though. Now, if that carbon was one of the ferrite mixes, it could make a significant increase in the inductance of that 'coil'. Ferrite 'beads' used on the coax is another way of stripping CMCs from the feed line, right? But then, a coaxial choke is just a 'cheap', quick-n-dirty way of doing that stripping without the extra weight/cost of ferrite. That 'slug' in a variable coil is just one way of making 'smaller' changes (tuning) a coil. That'd be a nice feature for a choke, but adding/subtracting a turn or two would do the same thing.
- 'Doc

(Oh! And paint that choke pink! What self respecting electron would wanna have to go through that??)

 

[Wrench]

TVI problems with a neighbor? All TV's have High pass filters, or use cable. It must be an old heirloom TV to overload the circuits.
Why not just use a low pass filter? I don't know where you live, but here in Tampa, people run linear s at home without disturbing TV. All TV's are High Definition, and TV channel 5 is not used. TV Channel 5 is on 54 megahertz, which is a harmonic of 27 Mz. (27 + 27 = 54) Soon. TVI will not be a problem, as more communities restrict TV antennas, and you will have to use cable. I use cable on my four year old 32' Samsung. Although I live less than 1/2 mile from a truck route, I never get any interference. There is no TVI problems in at least the county I live in.
Of course, the community standards concerning antennas would keep CB use pretty low, or even Ham radio, I just turned a close line into a stealth dipole.
I would like to put an Antron on the roof, but two things stop me. The rules, and the fact that Tampa is the lightning capital of the US. Putting a big stick type or Antron inside a flag pole would be OK, but the effect on SWR and cut down radiation would mess up the radio.
So what can you do, the official stand is no one uses CB anymore, they drive and text.

 

[pkmak12]

My neighbor has a new TV in her living room and it does not effect that TV, its her old TV in her bedroom that gets it. I dont bother any of my TV's or anyone elses in the neighborhood.
Also I have a bunch of ferrite cores here would it do any harm placing them on the coax before and after the choke?

 

[W5LZ]

Putting those cores on your feed line shouldn't harm a thing. I also don't think they will do a lot of good either. That's not where the problem is, or the most likely source of that RFI.
- 'Doc

 

[GnG8d]

Overmodulation.

^^ watch your modulation

 

[K9GAS]

There are some components you just can't keep it from. Your offer to buy the tv was probably the only solution.
It's what's coming out of your antenna, normal signal. With the age of that set, probably no rfi/emi shielding. As suggested possible that a high pass filter will work, I've not had any luck with some sets, especially old sets.

 

[Captain Kilowatt]

TVI problems with a neighbor? All TV's have High pass filters, or use cable. It must be an old heirloom TV to overload the circuits.
Why not just use a low pass filter? I don't know where you live, but here in Tampa, people run linear s at home without disturbing TV. All TV's are High Definition, and TV channel 5 is not used. TV Channel 5 is on 54 megahertz, which is a harmonic of 27 Mz. (27 + 27 = 540

TV channel 5 is from 76-82 MHz. Channel 2 is from 54-60 MHz. Channel 2's video carrier gets whacked from CB's second harmonic and channel 5's audio carrier gets hit from the third harmonic. Any TV with a highpass filter can still be interfered with from frontend overload if the signal is strong enough which has nothing to do with harmonics.

 

[pkmak12]

I was wondering if I used a barrel connector to add 5- 9 feet of coax will that effect my swr's or signal?

 

[Needle Bender]

First, make sure some bonehead didn't tune up that radio to get the most wattage he could by expanding the coil in the rear of the board. That's a low pass filter designed to keep the radio from transmitting on TV frequencies and having other harmonics above the 11m band, but which some watt meters will read as just more wattage output without making the distinction of frequency.
If it has been spread, simply buy a roll of waxed string and gently pull it back to a tight coil and tie the string around it to hold the tight shape, since they usually won't go back and remain in the original tight coil after spreading.
And if they will allow you, wrap their coax through a ferrite ring, 3 turns one direction, then reverse and 3 turns the opposite direction. That will help strip off the RF from the shield, a path not uncommon to TVI. Do it in two places down near the TV, 18 feet apart. It worked well for me and a couple others around these parts.

I was wondering if I used a barrel connector to add 5- 9 feet of coax will that effect my swr's or signal?

Maybe. It depends on how good a match you have at the antenna, and how well the antenna is isolated from the coax. Theoretically(I love that word) you shouldn't see much change, but realistically you usually will see some, hard to say how much. If you have bad RFI in your shack then that is one way to help cut down on it by changing the dimension of the shield so it looks less appealing as a path for your RF.

 

[BOOTY MONSTER]

That really only hold true for the foam type cores. The RG-8 with the solid polyethylene core is not affected and the centre will not migrate.

so if i'm using 213 coax with a solid polyethylene dielectric (and stranded center) it should be perfectly fine on my 4 inch diameter choke form ?

 

[Captain Kilowatt]

The center will not migrate in that cable so you should be fine. The issue is the softening of the foam core due to the sunshine heating the cable and the center slowing moving off center and eventually shorting to the shield.