CB Radio Basics: Discussion of 3ft Jumpers and what to do with them in Mobile use in particular

[@warrenscott9990]

Those exact 3 foot jumpers were the cause of my ossiclation and terrible SWR. Changed to nulled 12 foot 213 for 1st jumper and the results was what I sent you on my rig expert.1.01 SWR and 50.1 ohms. Excellent video Rooster

[@howardperkins7954]

Started out in radio 58 years ago and ran into some, if not all of those issues. Finally switched to the longer jumpers and none of those problems, (with the exception of the grounding issues), followed me, and the grounding issue was my fault, not the jumper. Good information that folks should listen to. Don't know why, and don't care. Fix your problem and save yourself some time and money! And don't coil your jumpers, but run them in line like a snake if you have to...

[@williamcharlesgatlin3436]

Thank you Rooster for the good information on the 3 foot jumpers !!!!

[@jgmopar]

Great video, Thanks Rooster. Even running a 3 foot jumper from my radio to my meter I had issues. No amp involved. I bought some of the 6-foot LMR400 jumpers from you and all the issues are gone. Your videos help a lot. So, I use the 6 footers when I hook the box in line as well and works great. I like these types of videos.

[@tedneitzel]

I never had any issues with 3 footers i used them for 40 years. But heres the thing you did a video a year or so maybe more and i changed my house my 2 mobiles to 6 footers and i don't get crazy readings on my meters anymore. Everything reads much more true in watt meters etc! Great info Mr. Rooster!

[@kencarlock4940]

Only run half wave jumpers, have had too much trouble with reflect from odd lengths. Great video!

[@franciscolopez3229]

It is true, it is a case to case basis. I am using 3 foot jumpers radio to amp then to a meter and had no issues at all. SWR stays the same so is the Reflect with the amp ON or OFF in my base station. Most probably it'll be a different case when I put a setup in my vehicle. Having said that, thanks Rooster, this exchange of ideas from you and everyone on the comment section is a big help to further understand this issues. All the best.

[@lawnmowerman2199]

Thanks so much for sharing your experience with us!!

[@hazmathauler4536]

Thanks for the info! The only time I run 3’ jumpers is when I’m testing stuff here at home and that’s with LMR 400.

[@justinrayguitars6024]

I've heard all the scientific stuff about 50 ohm's and how it doesn't matter. But I'm with Rooster on this one 100%. I have had nothing but problems with 3ft jumpers so simply don't use them.

[@Johnny747CB]

Good advice Rooster

[@OscarRamos-e9t]

100% true, I always use the best quality coax and when my 3 ft jumper gives me bad swr I install a 9 ft and swr goes down to perfect.

[@chesleypage7505]

So very true !

[@Triple_3_In_The_Ozarks]

Coaxial lengths are always a great way to stir up a hornets nest of opinions. Experimentation is part of the hobby.

[@christophersmith1155]

you are 100% correct. the same thing happened to me in my base. i learned the hard way. Now I only use 6 foot jumpers. and only RG-213. . Not mini 8U. another bad choice.

[@jasoncain5930]

Rooster most definitely 💯

[@lightsout7034]

100% agree I ran a 3ft from my 6pill to my meter an it wouldn't unkey switch to 9ft then no problem

[@mattikankaanpera1979]

I agree, half a wavelength is the best measurement for a jump cable, because the desired 50 ohm transfer at both ends of the cable is the same. At all other lengths it does not happen and there will be SWR problems with the values and the antenna is out of tune. In my opinion, with an antenna tuner, the situation can be made to appear that everything is fine, but at that point you are only deceiving yourself. 🤔

[@frppower1]

Thank you rooster for the information.

[@jamesrickman8655]

Do a video on correct jumper coax location when running a amp along with a watt meter on a radio for newbies and people like me thats getting back in to the hobby!

[@TheElectronMan]

This is 40+ years of experience talking so I’m not going to argue about this, but this debate has been ongoing for years. Personally, I use the shortest coax I can practically manage I don't measure the length I use what I need. The fact is, in a CB radio amplifier setup, the specific length of a 3-foot coax jumper has no significant effect on system performance at 27 MHz if the equipment is properly matched and installed. Claims that coax length is critical are often based on misconceptions or improper setups. The focus should be on proper tuning and high-quality components for the best results. Some argue that coax length should be a multiple of a quarter wavelength (electrical length) to "tune" the system. However: In a properly designed system, the jumper length doesn’t need to correspond to a specific wavelength because the system components (radio, amplifier, and antenna) are designed to work together without relying on coax length for tuning. If the system has poor impedance matching, changing the coax length might appear to "fix" the SWR, but this only masks the underlying issue rather than resolving it.

[@Rooster_Radio]

@@TheElectronMan as I mentioned, your opinion, your experience. Yours may differ than others, but I can tell you that personally, I can't count on all my fingers and toes the amount of people that have encountered issues using 3ft jumpers, when replacing with a longer length the issue stopped. Why was that the case? Who knows? My guess is because in a mobile the amp is in very close proximity to the antenna which can cause all sorts of issues, you can read a lot about the subject itself. This has been something I've seen with almost every brand of amp, different antennas, radios etc. Does my 25 years make me the most qualified or knowledgeable? Nope, all I can speak on is what I've experienced. Did the 3ft jumpers cause the issue or did the longer jumper resolve it? Either way you want to look at it, removing the 3ft from the equation has solved a lot of issues. Are people running 3ft jumpers without issues? I'm sure, but at the end of the day, why take the chance?

[@TheElectronMan]

@@Rooster_RadioOh, don’t get me wrong-I’ve seen plenty of situations where changing the coax length made a difference. However, electrically speaking, it really shouldn’t. My guess is that if changing the coax length affects the SWR, it’s likely because the system has poor impedance matching. Adjusting the coax length in these cases only masks the underlying issue rather than truly resolving it. That said, I get it-sometimes you do whatever it takes to make things work. It’s no different than using an antenna tuner to address an impedance problem. Vehicles, in particular, often exhibit unusual RF behavior due to the mix of metal and design complexities, which makes them more prone to these quirks. By the way, I love your channel! My response wasn’t intended to be negative at all-just sharing my perspective.

[@Rooster_Radio]

@TheElectronMan I didn't take your response as negativity at all! Customer in this case had a good swr, which can also be the case. You don't necessarily need to have a poor standing wave to have common mode current problems. Example, we set up "direct fed" beam antennas which feed directly to the driven element. You can tune them to a flat match, no balun. However once you start running significant amounts of power common mode current will become an issue

[@TheElectronMan]

@@Rooster_Radio Thank you for sharing your perspective! I completely agree that a good SWR doesn’t always mean you’re free from common mode current issues, and your example of direct-fed beam antennas is a great illustration of that point. However, I’d like to add a nuance. While it’s true that you can achieve a flat match without a balun, especially in a direct-fed design, the presence of common mode current often points to an imbalance in the system that isn’t addressed by SWR alone. For instance, even with a flat match, a proper balun or choke can prevent unwanted RF from traveling on the feedline, improving system efficiency and minimizing RF interference or feedback issues at higher power levels. This is why many operators, including myself, prioritize a good balanced feedline and use baluns or chokes, even in cases where SWR readings are favorable. It’s not just about achieving resonance but also about maintaining the integrity of the entire RF system. Thanks again for the discussion-it’s always great to share insights on these kinds of technical details! But I will be honest there is a little bit a voodoo involved in the game of RF, I have seen things that work that shouldn't and things that should that don't so yeah if a longer or shorter coax helps go for it.

[@vegasfordguy]

I heard that you got a huge lot of 6 foot jumpers to sell! LOL, just kidding. Good advice. It's crazy how something like this can cause issues like this. Sometimes 3 foot jumpers work just fine, but it's definitely better to be safe than sorry.

[@J20ginger]

100% true I’ve had this happen to me

[@TimMars-zv7wj]

Hey Rooster great info! Would you say 1ft and 2 ft patches are a safe bet, or would you stay away from 3ft and shorter? Thanks!

[@jefffritsche9974]

Great video. I'm more of a newbie. I have 60 feet of RG8X running out to my antenna. I'd like to get one of your 6 ft. jumpers to run between my radio and my SWR/power meter. I see you have several cable types of jumpers (none RG8X) -- what would you suggest for my purpose ?

[@Rooster_Radio]

Lmr240 uf

[@TheMajictech]

In my experience the “rules” almost never apply. For instance I have yet to see good swr readings in a mobile application with an 18 foot coax. I’ve found 9 to 12 ish feet to be ideal in every case I’ve owned or installed.

[@356byu]

Rooter do you have any Voyage 9000 radio settings around 🤔

[@Rooster_Radio]

@@356byu don't

[@kubford6865]

Well, if the two items are only three or 4 feet apart and I run a 9 foot jumper, what do I do with the excess? Do I stuff it somewhere or do I coil it because I thought coiling it is not good. It creates a kind of choke somehow. So, what do we do with all the excess coax?

[@TheMajictech]

Figure 8

[@bryantdunn7984]

What about Coax that's zeroed out at 1/4 wave with Antenna analyzer?

[@Rooster_Radio]

I mentioned coax cut to specific wave lengths in the video

[@sm9798]

All you are doing is tricking the meter by adding coax. You need to tune the antenna with a proper piece of coax for your desired frequency. Then use said coax for tuning your antenna. After this has been achieved, jumper length shouldn’t be an issue. If it is, as you said, you have other issues. RFI/TVI, how thick the metal on the vehicle is, the vehicles paint can even cause an issue. As you stated mobile setups are a little different, but using a 6” or less jumper to the antenna for tuning will work just fine. Just make sure the coax is of good quality and that the connectors are of good quality and are installed correctly. Clean in equal clean out. I have used my TNT600 with my icom 746, and had no issues with VSWR. My VSWR stayed under 1.2:1 with amp on and transmitting.

[@Jimshireman-v3z]

Trust your experience rooster

[@jasoncain5930]

Yes throw away 6ft and 12 they work good

[@Mike-io3ks]

Meter inline?????

[@BentConrod]

Research Circle of Constant VSWR.

[@68hoffman]

kool channel mang ..umm what coaix types are the best for noise and such ...i know this is not ideal for any place for a cb ..i live 100's of yards from a million+ watt power grid ..lol..i can hear it hum outside ..lol..but any help would be appreciated :)

[@Rooster_Radio]

The best shielded you can afford. Lmr400uf is a good starting place

[@68hoffman]

@@Rooster_Radio thanks :)

[@clems6989]

The "Crazy" things are not related to your feedline. They are caused by common mode currents.

[@Rooster_Radio]

Correct, which has many causes including the transmitter being too close to the antenna, which I believe can be solved by: creating a balun/choke, or can sometimes be defeated by using a longer jumper length, putting more "electrical distance" between the antenna and transmitter. Be sure to share your thoughts

[@servicetrucker5564]

Guess I’ve been lucky for a long time now. All I’ve ever used is three footers

[@Rooster_Radio]

Guess you have. If you're one of the doubters take a scroll through the comment section and read up. Like I said, they don't always cause issues, but often times do 😁

[@kilroy205]

[@Mike-io3ks]

No news is good news

[@larrychampion8848]

Would it matter if a 6 foot jumper is used and is coiled instead of a straight line?

[@Rooster_Radio]

In my opinion and experience it would depend on how tightly you have it wrapped, but yes coiling coax can have effects as well

[@larrychampion8848]

@Rooster_Radio Thanks for the feedback. I used a 6 foot jumper on a base to RM Italy amp and have had a 1 or 2 coil wrap and found amp to sometimes change SWR readings. Just throwing it out there

[@dangermaine4739]

No wonder why my girlfriend kept getting shocked.. from my Palomar 225.W with 1446 2~pill 💊 I think that's the pills.

[@stevenackerson8810]

Or one other idea, give it to your worst enemy! LOL

[@Rooster_Radio]

Yes!!!

[@jasoncain5930]

Throw it away

[@MtrixMan007]

3 foot jumpers are bad. 6 or 12

[@David-qf6ls]

I Use Nothing But Belden Coax Just Saying. 🇺🇸👍

[@MtrixMan007]

You act like someone's ready to argue with you.

[@Rooster_Radio]

They are 🤣🤣🤣. Scroll through the comments and you'll find em

[@mr.stonerUDX714]

3 ft jumper is a NO NO

[@Rooster_Radio]

Bingo!