RFI

Heavy Metal · Apr 18, 2015

I read a few articles this is really a good one On RFI chokes I thought plus looking at ideas based off it.

www.k3dav.com/rfchokecoil.htm

Here he shows these pics

Also found this using type 31 cores and its 12"

Plus thought using @18"-21" of these

On RG 9913 and the 8" 8 turns to be safe on not only RFI coming back down into radio but being heard on other things or interfering or am I over doing it?

Which works best or can both be used

I thought of using Snap ons from PL-259 @18"-21" down to the 8" circle of 8 turns of coax. What do you think of this any other suggestions.

918Oklahoma · Apr 20, 2015

Id like to know too for my g5rv jr. Thats about to go up. I was planning on doing the 8 8" wraps right at the feed point to the ladder line.

dave457 · Apr 20, 2015

There is plenty of good info on this topic in this forum. Just use the search feature

Moleculo · Apr 21, 2015

Both designs will work. The version with the ferrite is called a W2DU balun and works very well. For best usage, you'll want to pay attention to the type of ferrite: mix 77 or 31 is what you want for HF; 43 is a good choice for VHF.

Heavy Metal · Apr 23, 2015

31 is good from @1.5 MHz to @300 MHz

My Thing is how many ferrites to use along the 18" to 24" stretch before doing the 8", 8 turns?

Speaking for HF to 6m maybe to 300

Heavy Metal · Apr 23, 2015

918Oklahoma said:
Id like to know too for my g5rv jr. Thats about to go up. I was planning on doing the 8 8" wraps right at the feed point to the ladder line.

I was thinking of @8 to 12 of these

Sorta like this

From feed point down maybe 18" to 21", then the 8" 8 turns. And I'm using 9913f7 coax.

Moleculo · Apr 24, 2015

Heavy Metal said:
31 is good from @1.5 MHz to @300 MHz

My Thing is how many ferrites to use along the 18" to 24" stretch before doing the 8", 8 turns?

Speaking for HF to 6m maybe to 300

the classic design is about 10" of ferrite.

Captain Kilowatt · Apr 24, 2015

Just a note about this piece of bad advice.You do NOT want to follow this advice. If you choose to make the coil without a form in the middle as shown in the green circle the coil should not be scramble-wound as shown. It will work.......somewhat, but it will work better if the turns are neatly side by side. Scramble-wound as it is called allows for more coupling from one turn to the next and basically upsets the current making for a poor choke.

vkrules · Apr 25, 2015

yes you can over do it this site may help http://www.karinya.net/g3txq/chokes/ one size does not fit all i would have thought his 8 x8 would be more suited to 20 meters may be its the scatter wind thats the problem

Heavy Metal · Apr 26, 2015

vkrules said:
yes you can over do it this site may help http://www.karinya.net/g3txq/chokes/ one size does not fit all i would have thought his 8 x8 would be more suited to 20 meters may be its the scatter wind thats the problem

Seen that my thing is this, I have 9913f7 and LMR 400 UF being flexible or not aka 9913 and LMR 400, my thing is what is best as far as air coiled vs coiled around so many in diameter piece of PVC or Air wound( turns and dia needed ) it would take to cover 1-14MHz, 10-30MHz, 10-60MHz, or 1.5-60MHz in general to keep RF comming back in to shack ect as well as RFI period.

Heavy Metal · Apr 26, 2015

Captain Kilowatt said:
Just a note about this piece of bad advice.You do NOT want to follow this advice. If you choose to make the coil without a form in the middle as shown in the green circle the coil should not be scramble-wound as shown. It will work.......somewhat, but it will work better if the turns are neatly side by side. Scramble-wound as it is called allows for more coupling from one turn to the next and basically upsets the current making for a poor choke.

So be better like the pvc but open air vs wrapped around pvc same amounts 8" 8 turns or same length but can be on 2" form or so?

Heavy Metal · Apr 26, 2015

Moleculo said:
the classic design is about 10" of ferrite.

So another words clip on @4 to 6 of them making about 10" in length like this

Or like this but al one after other no gaps between them?

Captain Kilowatt · Apr 26, 2015

About six turns neatly wound into a coil about eight inches in diameter is going to work if it works at all. Turns should be side by side and not overlapping.

Stellasstillarat · Apr 28, 2015

Davy Metal, post: 518640, member: 42492"]I read a few articles this is really a good one On RFI chokes I thought plus looking at ideas based off it.

www.k3dav.com/rfchokecoil.htm

Here he shows these pics

View attachment 15518

View attachment 15519

Also found this using type 31 cores and its 12"

View attachment 15520

Plus thought using @18"-21" of these

View attachment 15521

On RG 9913 and the 8" 8 turns to be safe on not only RFI coming back down into radio but being heard on other things or interfering or am I over doing it?

Which works best or can both be used

I thought of using Snap ons from PL-259 @18"-21" down to the 8" circle of 8 turns of coax. What do you think of this any other suggestions.[/QUOTE]
Excellent! Excellent! Excellent! Thanks for sharing the article.

Heavy Metal said:
I read a few articles this is really a good one On RFI chokes I thought plus looking at ideas based off it.

www.k3dav.com/rfchokecoil.htm

Here he shows these pics

View attachment 15518

View attachment 15519

Also found this using type 31 cores and its 12"

View attachment 15520

Plus thought using @18"-21" of these

View attachment 15521

On RG 9913 and the 8" 8 turns to be safe on not only RFI coming back down into radio but being heard on other things or interfering or am I over doing it?

Which works best or can both be used

I thought of using Snap ons from PL-259 @18"-21" down to the 8" circle of 8 turns of coax. What do you think of this any other suggestions.

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RFI

Heavy Metal

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