Chokes and Baluns
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- čas přidán 5. 04. 2024
- Baluns and Chokes come in all sorts of sizes. They are often attached to coax feedlines. Why do we need them and what do they do?
Videos discussed in this video:
• Radiation Patterns ERP... Radiation Patterns
• 7 Different Antennas 7 Antennas
• How to Build a 4:1 Bal... Mike and Callum's 1-day build - Věda a technologie
You know Callum. I'm an advanced licensed holder here in VE3 land and I'm really enjoying your crisp clear walk through of the foundation hand book. Nice work please keep it going. All the best. 73 Dave :)
Awe thanks Dave!
The drum roll before the sneeze is a great touch. Always good to refresh yourself with ham info.
got my foundation test next saturday. your videos have helped a lot
Good luck, I'm preparing for mine!
@@richardmillican7733 I'm sure you'll be fine fingers crossed for you
@@richardmillican7733 I'm sure you'll be fine and pass
Good luck both. I passed mine last Tuesday. You will nail it.
G'luck!
Great stuff Cal. Just an update from me commenting on a previous video, I passed my intermediate last week! Good bye MW7FMD and hello 2W0KUI
Nice work!
keep it coming Callum .. love the presentations .. I've got this . .. no, maybe, possibly, not yet .. but I'm working it!
You can do it!
Tnx Callum
Hey, Callum, I enjoyed this video and I think what your doing for Jim W6LG is part of what we hams are all about. Thank you for that.
Awesome, thank you.
Ferrite clamps work exceptionally well, I have them everywhere.
I decree that it shall now be known as the "quite attractive" balun.
-Callum Commander 😂
HAHA
Great series, Cal makes these fun which makes the learning easier.
Glad you like them!
Always entertaining with lots of information mixed in. Thanks!
Cool, of you to do this Cal!!! I wish I would have had it when I was studying for my tickets..
This channel cured my vitamin D deficiency.
And mine!
Baluns are absolutely critical. I've had many issues with RF feedback in the past and so use either an FT-240-31 or FT-240-52 and just wind as much of a 0.5m SO-239 to PL-259 as I can around the former as I can. I use them with all of my feeders and also between my mic and my audio interface as I was having an issue with RF getting into that on 20m.
Just make one up and be done with it when you install na antenna - makes life so much easier.
Also had problems with my portable station with RF getting back along the control cable for the ATU. Just put a balun in place on every cable between your transceiver and anything else connected to it. Even USB cables to your PC. It's a PITA but absolutely worthwhile. Nothing more soul destroying than calling CQ to get no answers because you audio sound ropey due to RF getting back into your transceiver.
I've been running these style for HF (CMC-130-3K). They make other model which works HF through 6m. I think there are two manufacturers. Also, properly grounded antennas/shack might help as well.
ABR has some patch cables with chokes built in. And are made in Choke City: Houston.
BRILLIANT!!! 👍💥
Cheers Callum for the video, although i don't really need the RSGB to tell me how to fall off a ladder, i worked that one out myself with the help of gravity !!
Woops!
Fantastic! transmission line transformers, several really good books by Jerry Sevick W2FMI.
Hello Callum , thank you for sharing & excellent information as always .
I have researched chokes and baluns & the common mode current effect .
My findings regarding the common mode current effect is quite scientific & involved .
By and large there are 3 types of radio communication arrangements , home base , vehicular & portable , my particular research findings was based on the home base set up and vehicular radio transmission.
The chokes & baluns you've described are no doubt effective and is indeed incredibly valuable information .
I'll trim all the information down as best I can , common mode current is essentially an electrolytic effect within the conductor , the conductor effectively becomes a capacitor due to the potential difference of electrons that are being generated between the inner dielectric core , metal film , screen & the polyurethane covering , it's these layers that build a capacitance , hence polyurethane electrolytic capacitors more or less have the same properties & it is exactly the same process within the coaxial cable .
The best way to eliminate common mode currents is to slug the coaxial screen to ground , this will immediately discharge the electrolytic effect commonly known as common mode currents .
Most home base units are grounded by the earth on the 13.8v power supply , for example if you place an ohm meter probe from the PL259 outer ring at the rear of the radio & the second probe to the earth on the plug socket it will read around 0.1 ohm to ground& that's generally more or less satisfactory to the average radio operating home environment .
The problem with the electrolytic common mode current mainly lays within vehicular & aviation radio use , hence no ground , sea vessels are somewhat better , but certainly for mobile field set up or vehicular operation a ground electrode stake that is satisfactory earthed is advised .
generally the above information is not common knowledge , the following scientific effects from electromagnetic RF transmission depending on what antenna & conductor materials are used are as follows , electrolytic with conductors , electrolysis with aluminium , osmosis with fiberglass , sadly all these materials succumb to degradation through electron use , particularly if exposed to ingress , then the laws change to hydro effect which is common & I shan't go into all that ,it's been found within aviation ferrite or any other material method used on the exterior of the conductors will have little effect due to the above reasons , but every little helps I'm sure .
I hope that the above has been of some help .
Wow. Excellent analysis.
@@DXCommanderHQ Thank you Callum .
Would be nice to see the tutorial on how to add the chokes in MMANA
Chokes don't affect impedance but baluns do.. Go to the Calculate Tab. Click "Optimisation". Then click button "Advanced". Check on to the Environment tab. Change the value in the R box to say 200 (for a 4:1 balun). Now click OK. THEN click on Cancel. Done.
Made an ugly balun similar to the one pictured... top tip...
As it's almost impossible to get shrink wrap that diameter... a length of car inner tube cable tied just after the pl259's made it look a bit prettier 😊
I guess the main issue with Ugly Baluns is that they are pretty narrow banded and only seem to work well across one or two bands.
Good point Tim!!
Passed my foundation Tuesday. Waiting for certificate now. By chance I ordered some parts to make a 49 to 1 for a diy efhw antenna earlier.
Great!
One should always look at the trade-offs when adding connectors and higher loss coax such as the separate box you constructed when comparing insertion losses with your radiating devices ie. (antennas, whatever the design). Sometimes the ugly choke is the better choice.
On HF, that box would have marginally - almost immeasurable loss.
I have an ugly balun on my attic antenna, it's RG8X wrapped around a Tesco ginger beer bottle.
Best sort!
Hi Callum - I want to measure the choking impedance at a specific frequency with a VNA - can you tell me how to do this please - thanks Dave- Great video series - from me an old timer
I don't know how to.. But Steve's method is explained.. Just search for "g3txq common mode chokes" and his article explains how he did it.
@@DXCommanderHQ OK great THANKS Callum - 73 Dave
Nice work on that common mode choke Callum. Yeah, it makes more sense to build one of those chokes than pay for 7 snap ons at $20.00 a piece. Wow!
I have one question though. Is that 4:1 balun you showed a current balun?
And your talks on common mode chokes and balun are never boring.
Cheers from Texas!
de Rick, WD5L.
Rick, I never worked out the difference between a voltage balun or a current balun. I was just reading about this last night. I now (almost) know the difference (I think) but we'd have to ask Mike!
Callum, I’ll check it out. I’ll let you know what I find out.
Oh, one question. Why did you use mix 52 and not mix 43 for your common mode choke?
On the topic of Jim, W6LG, you should probably see his latest video if you haven’t yet.
Great video. As a new licence holder I've found that the Foundation course and exam really doesn't prepare you very well for the actual realities of getting on the air when you are suddenly thrown into the deep end of equipment and certainly antennas. For instance, Ive bought a JPC12 aerial, but I don't know if I do, or do not need a balun. I know its grounded with the spike and radials and that's its apparently rated as 50ohms, but trying to find a Yes/No answer involves trawling through Reddit, forums, Google and everywhere.
a common mode choke is good practice no matter the antenna on HF frequencies. It helps to stop the coax being used as a ground radial as well
@@jamesemery1 Thank you for the reply. So, if I clamp some ferrite cores onto the RG58 cable at the antenna end of the line, would that be a correct or usable solution?
@@GunnyWombat yes
@@GunnyWombat Get a ferrite toroid and wind coax around it. It will cost a lot less and you should get a better result as the effect is given by the turns over the material. A single clip-on will give you effectively a single turn - multiple turns over a toroid will give you multiple times the effect of a single clamp-on. Simply put, seven turns around a toroid will be similar to seven clip-ons.
Do some of the higher end manual antenna tuners have built in chokes?
Interesting. I don't know.
As a new ham ,love your stuff I’ve learned a lot thanks KQ4OHB
Welcome!
Efhw 49:1 what would be best place to install a choke for good housekeeping
Cheers Callum enjoying videos 👍👍
are you using a counterpoise or using the coax as the counterpoise?
As per the manual for [ENDFEDZ ALLBAND-KW 80-10 EFHW 1KW ICAS ANTENNA] there are 3 ways - choke, counterpoise, ground rod. See page 2 figure 2 of that manual for thorough overview. I use a 7 turn coil through ferrite 1/4 wavelength from feedpoint.
@@jamesemery1
Using coax at moment about 20m m&p.Trying to decide if a wire counterpoise be better.
Any help appreciated
If you plan to have the coax act as a counterpoise, place the CMC (Common Mode Choke) near the operating position. If you have a separate wire acting as a counterpoise or a ground rod, place the CMC near the antenna (as near as practically possible). The latter is so that the antenna is prevented from using the coax as counterpoise.
@@danjor_droneitsme6874 @kuyakano8976 explained it perfectly
I use 11 meters I have a 5/8th bottom fed using Mini RG8 and I have 5 clipped on ferrite clips at the base of the antenna my SWR ranges from 1.1 to 1.5 through 80 channels I don't know if the ferrites are doing any good or not ?
take them off then check the swr that will tell you something
Consider the loss first.. czcams.com/video/SnEfMDh2B3M/video.html then as James says, take them off and find out :)
@@DXCommanderHQ I'll have to do it when the wind has dropped as it's about 30 foot up on a scaffold pole on a elbow I double checked from a distance and can see 4 ferrites they are all in heatshrink tubing I also have a lightning arrestor at the base of the antenna with a thick copper wire running down the pole to a copper rod but as soon as I can I will do as James has advised :)
chokes and baluns are the most confusing thing to me.
An antenna impedance match or mismatch has nothing to do with common mode current on the feedline, a perfectly matched 1.1 impedance match can have as much cmc on the braid of the feedline as a higher impedance mismatch, common mode current is the result of antenna imbalance ,or feeding a balanced antenna with unbalanced line
That's what I was thinking. What I would refer to as a choke doesn't do any transformation or change from balanced to unbalanced. Coiling your coax will reduce common mode, acting like a choke, it won't act like a balun. Also, you can get 1:1 baluns so you don't really need any impedance transformation to call it a balun either. I think a balun will act like a choke though right? Maybe that's where the two concepts cross?
I could be wrong too, this isn't my strongest subject in the hobby.
@@piquat1think where its misunderstood by many is that its thought that reflected power from an impedance mismatch travels on the outside of the braid ,it doesn't it travels on the inside of the braid, the braid acts as two conductors
Hope Houston pro sports teams do not look at this. We are known as Choke City!
Oh! LOL