Clip on ferrites

Do Ferrite clipon's really cut noise on interference, I don't really want a coax fugly balun

Hi Bernie,

Depends on where you clip them and what size you use.

If you have the big clips on types you can make several wraps of cable through them and get good choking but if using smaller ones that only just clip over the cable you'll need several. I think one turn through a single ferrite (wire through twice) is equivalent to six ferrites using single feed!

I have two chokes on my antenna setup but then I use a doublet that is ladderline fed. One is a 'Maxwell choke' that uses 10 clip on types but a mix of 31 & 43 material on my coax feed from the ATU/Matcher to the rig. (The other is a fat old toroid on the ladderline feed side of the ATU/Matcher.)

Then again I'm using my antenna for everything from 1.8MHz to 30MHz.


If you're after simple RF common mode choking for CB frequencies the air wound coax choke is by far the easiest to implement on the coax at the antenna end. Five turns around a diameter of 4.25 inces will do the job nicely, (100mm or so.....soil/sewerage type pipe is a nice size and available form the local DIY/trade outlet), as per the chart provided by Steve Hunt G3TXQ(SK) :-

http://www.karinya.net/g3txq/chokes/


Yeah, I know, we never used to have to do this sort of stuff back in 19-clickety-click ya-da-ya-da, but we didn't always know enough either.


There's a wealth of information on the old web about such stuff but beware of the 'clip-on-everything-everywhere' mentality or it'll cost you a fortune in ferrites and won't always work.....so you clip on even more!

Also be aware of 'cheap' clip on ferrites, most are useless and probably not even ferrite material so a total waste of money for an apparent bargain.

Give the air choke a go first (dirt cheap) as you'll be surprised of what effects common mode currents can cause.
Start worrying about clip on ferrites afterwards....on other equipment....if you need them.


As per usual 'you takes your choice' (and others may disagree) but I'm not selling you anything for my cash profit or asking you to 'like-and-subscribe' either. Just simply doing my best to help a fellow radio enthusiast where I can.


73...73's...(that can be argued the toss as well )

All the best,
Victor



(BTW, if you have loads of QRM, switched every RF gain switch/knob all the way up or even the time of day or year/decade with atmospheric/propagation noise or 'Over The Horizon Radar' interference.....nothing will help!)


Oh, and apologies for the 'waffle'....I could've replied with "Yeah they do", or "No they don't do nuffin mate".

Hello Victor,Did just that as you suggested quite a while back with the clip on (clam type) ferrite and also the common mode choke.I’d say it works as I don’t seem to hear or be told of any RF.So thanks again and please waffle on as it’s informative and very helpful to all.
Cheers Tom.

I'm sure there's a way of testing these ferrite chokes, I've got one of those nano vna things and it could probably do the job, err... except I haven't got a flippin' clue how to, lol. I have had a look into the 'how' but it just makes my brain hurt. Who said retirement was fun, I'd like a word with them

I should also add that I have a bag full of clip on ferrite chokes of several different sizes including about a dozen that fit nicely on RG213 coax, and at least one or two on every cable (power, coax, lights, PC etc) in my 'shack'. Ah the quest for a quiet life continues ...

Chokes are very easy.
Buy 2.4inch rings 43 or 31mix.
Use a length of decent RG58 and wind on 8 to 12turns.
Put connectors of your choice on each end and fix at antenna feed point, seal connectors.

No box needed as these rings are waterproof just keep ring away from metal objects.

You can put two in series if you have a more difficult case of RF in the shack.

Ivy Mike wrote:

Chokes are very easy.
Buy 2.4inch rings 43 or 31mix.
Use a length of decent RG58 and wind on 8 to 12turns.
Put connectors of your choice on each end and fix at antenna feed point, seal connectors.

No box needed as these rings are waterproof just keep ring away from metal objects.

You can put two in series if you have a more difficult case of RF in the shack.

Yeah, and don't drop them or hit them against anything either - which is why a box is not needed but sometimes helps depending on install!

A good reference for impedance vs. frequency vs. mix/windings is here:

 http://www.karinya.net/g3txq/chokes/

Deja-vu Jeff, same link I posted.
(Better twice than not at all.)

Steve Hunt's work was fabulous and it was so generous of him to share that knowledge before he unfortunately fell S.K.

The reason I suggested the 5 turn coax choke Bernie was it's the easiest solution and looking at Steve's chart provides the highest impedance against common mode currents at CB frequencies.

I think I may need to make an air choke after all, at least it is doable I have loads of coax and a length of 4in pipe.

Victor wrote:

Deja-vu Jeff, same link I posted.
(Better twice than not at all.)

Steve Hunt's work was fabulous and it was so generous of him to share that knowledge before he unfortunately fell S.K.

The reason I suggested the 5 turn coax choke Bernie was it's the easiest solution and looking at Steve's chart provides the highest impedance against common mode currents at CB frequencies.

Ah yes, so you did.  I’ve posted it before too, as it’s such a valuable resource and he was a huge loss to the hobby.

I tend to run a 43 mix choke for most things, sometimes 31mix for the lower frequency stuff.  

One day, I’ll have somewhere to put his version of the Hexbeam too.

The more the merrier Jeff and as many places as we can to pass on his invaluable work.

43CT016 wrote:

Ivy Mike wrote:

Chokes are very easy.
Buy 2.4inch rings 43 or 31mix.
Use a length of decent RG58 and wind on 8 to 12turns.
Put connectors of your choice on each end and fix at antenna feed point, seal connectors.

No box needed as these rings are waterproof just keep ring away from metal objects.

You can put two in series if you have a more difficult case of RF in the shack.

Yeah, and don't drop them or hit them against anything either - which is why a box is not needed but sometimes helps depending on install!

A good reference for impedance vs. frequency vs. mix/windings is here:

 http://www.karinya.net/g3txq/chokes/

I did put mine in small plastic boxes, as you say it does make them nice and neat.

The Hustler antenna has the DX Engineering feed line choke at the feed point and my homemade choke
just before the entry panel.
The Cobweb has a homemade one at the entry panel.
Both are 2.4inch rings wound with 8turns of RG142 mix 43 for the cobweb and 12 turns of RG142 on a mix 31
for the Hustler.

Anyway, any choke is better than none.

Wheel Nut wrote:

Do Ferrite clipon's really cut noise on interference, I don't really want a coax fugly balun

Are you having RF problems, Bernie? I just made a couple of "dirty baluns" for my most used frequencies, they really solved my problems Now need to make one up for 10-12m  but have run out of cable and connectors. I now know what I needed that cable for lol

13oots2 wrote:

Wheel Nut wrote:

Do Ferrite clipon's really cut noise on interference, I don't really want a coax fugly balun

Are you having RF problems, Bernie? I just made a couple of "dirty baluns" for my most used frequencies, they really solved my problems Now need to make one up for 10-12m  but have run out of cable and connectors. I now know what I needed that cable for lol

OH no.
 I dont get much interference now I have got the Solarcon up to its max height, could have been the stuff downstairs or next doors stuff.

How much coax do you need I have some left.

Hi Bernie, I think that chokes are more designed to prevent causing interference rather than receiving it.

Thanks for the offer of some coax, have already ordered some and some connectors.

13oots2 wrote:

Hi Bernie, I think that chokes are more designed to prevent causing interference rather than receiving it.

Thanks for the offer of some coax, have already ordered some and some connectors.

OK, i was going to send the rest back to you