CB Tuning question.

[Paniolo]

2006 CVO Ultra with the Harmon Kardon/CB built into the head unit.

How do I tune the antenna? I plan on buying an SWR meter (if you can recommend a brand I'd be happy), removing the fairing and hooking it up to the coax cable coming out of the CB radio.

Then what?
Key the hand held microphone and watch the needle swing over and then,....?
How do I know what it's telling me, and how do I know what needs to be done?

Any help with tuning the HD CB is appreciated.

Thanks

Lastly, I was surfing the HD website. Why are there different CB antennas for bikes made before 2009? Can run I the CB antenna off my cousins 2016 on my 2006?

[carioux2008]

In my past experiences dealing with CB radios (none on a bike though) many of them have different connectors. The original connection to the antenna was with a pl-259 and so-239 connectors (plug and socket?) New semi's have sma connectors on them sometimes, as its easier to run the cable through to the cab. Ive converted all of my antennas to BNC just to make things really easy when I want to "play". Those could be the difference. As far as tuning goes, you want your meter as close to the radio as possible, then you need to adjust the meter (cal) and finally check your swr. SWR is basically the amount of feedback you recieve when you transmit, and the higher the number the more feedback you have, reducing your actual power output. 1:1 is the theoretical best you can do. Anything below 2:1 is considered acceptable. You would adjust it by using a trimmer pot (resistor/capacitor/inductor) or by trimming the physical length of the antenna wire. The owners manual should detail this...who knows. Harley specific CB stuff is where im dim, and I apologize, just thought I'd give you a brief description of the general CB stuff.

[Paniolo]

Thanks for the reply. Silly question, but does it matter which end of the antenna is trimmed? Just pop off the rubber tip, and snip away?

[Rockout Rocker Products]

The antenna may not need to be trimmed, but rather made longer. At least on cars... it can go either way.

[Coyote]

The antenna may not need to be trimmed, but rather made longer.

[FSG]

Just pop off the rubber tip, and snip away?

yes but

The antenna may not need to be trimmed, but rather made longer.

and you wont know which until you make the first snip

[Coyote]

No, you don't need to alter the antenna to find out which way it needs to go.  Just checking the vswr on more than one channel will tell you that.

[FSG]

I've cut hundreds of AE's and mostly used Bird Thruline Wattmeters not the regular $10 to $15 SWR Meter from Radio Shack.

Yes you could change channels which changes the frequency and thus the wavelength and the SWR, BUT you need to be able to see that change on the SWR Meter you have at hand and that IMO is not always possible.

It is far easier IMO for the end user to just take the first snip, which is what I do/have done in the past.

[Coyote]

Well I'm an RF Engineer with 30 years experience, I also have a Bird Thruline Wattmeter and I can tell you I've never cut the antenna first and never had any problems knowing which way the antenna needed to go.     

PS, I've been known to use my spectrum analyzer with built in tracking generator and a directional coupler to do it as well.   

[FSG]

OK you win, I'm just an Electronics Engineer with over 40 years experience, most of that time spent in the Oil Industry.

Spectrum Analyzers and similar test equipment typically remained in the various workshops although I have been known to take Oscilloscopes into the Engine Rooms of older Offshore Supply Boats, adjusting Tachometer Senders on GM V8 and V16's, making life easier for the boat drivers. 

[PoorUB]

Let us know when you two are done measuring your, well, you know what!

Can you guys explain to use simpletons how to tell is the antenna is too long or just too short y just looking at a SWR meter?

[Coyote]

All I can say is I've never had to cut an antenna to know which way it needs to be tuned. 

Can you guys explain to use simpletons how to tell is the antenna is too long or just too short y just looking at a SWR meter?

Sure. Just check the VSWR at channel 1 (low end) channel 20 (mid) and channel 40(high end). If the the vswr is lowest at channel 1, then the antenna is tuned low and will need to be shortened to bring it up to mid range. If it's lowest at channel 40, then it's tuned high and you will have to somehow tune it lower (usually by lengthening the antenna).

If it measures lowest at channel 20, then it's somewhere in between. You can further pin it down by doing the same test just using the upper or lower half of the channels.

The problem with tuning the antenna on a Harley is that there just is not enough counterpoise (ground plane) to make a stable match. You can tune and get it OK at one spot, and as soon as you put a big bag or momma on the back seat it's all gonna change.

[FSG]

OK   CB Radio is in the 11 Metre Band

CB Ch01 26.965 Mhz         1/4 wave  2.781  Metres   

CB Ch20 27.215 MHz         1/4 wave  2.755  Metres                 

CB Ch40 27.405 MHz         1/4 wave  2.736  Metres

as you go up in channel number the frequency increases and the wavelength decreases

typical CB Antennas for Motorcycles, Cars, Trucks and Boats are 1/4 Wavelength with loading coils at the base, centre or at the top of the WIP

there is some preference for one over the other but there's no point going into that

the length of the Antenna is going to be a compromise across the operating band

so check the SWR on Ch 20 then check it on Ch 40

is it going up or down  i.e. if it was perhaps 2 is it going down toward 1 or up toward 3

if it's going down then the Antenna is too short, if it's going up then it's too long but check to see where it is on Ch 1

depending on the quality of the SWR Meter you may not see any significant change to be able to make a determiniation


Below is just a SWR Meter pic found on the web





Below is a Bird Thruline WattMeter pic found on the web, they have plugin elements to suit the power and frequency to be tested as well as many input and output adapters to suit equipment cable requirements

[FurryOne]

CB Ch20 27.215 MHz

Actually, CB 20 is 27.205MHz

The OP's best bet is to find his local HAM club and ask for help tuning because they should have a decent set of antenna measurement tools (That Bird gave me flashbacks!).  My personal opinion of H-D's CB antennas is that they suck.  I added a Firestik2 to my 17SGS because it's top-loaded and easily tuned, and even cheap!  ...And here's the results...

...and do I win the length game with 50 years? (Including managing an RF Technology section in a Govt. Research Lab?)   

[FSG]

Actually, CB 20 is 27.205MHz

Yes you're correct, my bad I had meant to type Ch 21 but really Ch 19 is the center of the band.

[Paniolo]

I'm not being a samartass, but now I'm more confused than ever. I didn't know  I had to tune at multiple channels, 1, 20 and 40. I never thought about having to lengthen the antenna, don't even know how I'm going to do that.

[PoorUB]

You don't tune for each channel, but you should check each end and the mid channels. You can tune the SWR to the channel you use most.

[FurryOne]

As far as tuning goes, you want your meter as close to the radio as possible,...

Actually, this is not true.  You want the SWR reading as close to the base of the antenna as possible.  Why?  The cable will throw off the SWR readings because few, if any, manufacturers supply the actual correct length (1/2 wavelength) of cable to match the antenna. (No, I have no idea why.)

[Rockout Rocker Products]

I'm guessing it's because a 1/2 wavelength is about 18 feet.

[Coyote]

The length of the cable makes no difference (other than add some loss which will make the SWR read lower at the radio end of the cable). For tuning, it won't matter where you put the meter but it's best to put it near the radio so you are farther from the antenna while tuning. Anything in and around the tour pack will pull the antenna tuning.

Every HD I've tuned, the antennas have always been long. I always recommend tuning to a low channel and just using that one. The reason has to due with how much of the antenna needs to be trimmed. I've found that if you tune them mid band (which would be preferred) you have to cut enough off the antenna that it's noticeably shorter than the FM antenna.

[Paniolo]

So am I hooking the SWR up at the radio in the front of the bike, or at the antenna at the rear of the bike?

[FurryOne]

The length of the cable makes no difference (other than add some loss which will make the SWR read lower at the radio end of the cable). For tuning, it won't matter where you put the meter but it's best to put it near the radio so you are farther from the antenna while tuning.

Say Whaaatt?  Sorry, but not in this reality.

Every HD I've tuned, the antennas have always been long. I always recommend tuning to a low channel and just using that one. The reason has to due with how much of the antenna needs to be trimmed. I've found that if you tune them mid band (which would be preferred) you have to cut enough off the antenna that it's noticeably shorter than the FM antenna.

That's why I'd recommend using an antenna from a Company that actually knows what they're doing, not one from a Company (H-D) who's main "competence" is something else.  And buy one that actually allows you to correctly tune it, not have to cut pieces off.

[FurryOne]

So am I hooking the SWR up at the radio in the front of the bike, or at the antenna at the rear of the bike?

If you can get to where the cable attaches to the antenna, it's the best place.  I believe the tour packs have a built-in antenna loading system that the short antenna screws into.  If you can get to where the cable connects to that, it's the best place for that type.  If you can't, then you can fall back to using the connection to the radio - your SWR will just be a bit off due to the cable, but better than not doing it at all.

[Coyote]

Say Whaaatt?  Sorry, but not in this reality.

It is most certainly reality. Changing the cable length on a matched antenna does nothing to what the radio sees. Changing it on a slightly mis-matched antenna will alter the phase and change the reactance (rotates you around the Smith Chart). Changing the cable length on an extremely mis-matched load (open or short) may alter the reading but that's not what we're discussing here.

I'm not saying you are wrong on measuring near the antenna if possible but there are good reasons not to do so on a Harley as I stated above.

In the end, most of all of this is picking nits. Pick whatever spot you want to insert your meter and tune it for lowest SWR and be done with it. It's not rocket science.

[FurryOne]

Let us know when you two are done measuring your, well, you know what!

Did I win?   

Can you guys explain to use simpletons how to tell is the antenna is too long or just too short just looking at a SWR meter?

Yes.  As you go from channel 1 to 40, the frequency increases.  As the frequency increases, the wavelength becomes shorter, so the required antenna length becomes shorter.  When you go from Chan 1 to channel 40, the required antenna length becomes shorter - thus going from chan 40 to chan 1, the required antenna length becomes longer.

So if your SWR is higher on chan 40 than on chan 1, your antenna is too long.  If it's higher on chan 1 than on chan 40, your antenna is too short.  If it's the same on chan 1 as on channel 40, your antenna is in tune - give yourself a pat on the back! 

Cheap SWR meters, like those $20 specials, are notoriously crappy.  That's why I suggest finding a HAM radio guy who'd be willing to lend you a hand. 

I use a RigExpert AA-30 Antenna Analyzer for CB antenna setup.  Here's a picture of the SWR showing that my antenna was too long before adjusting.  The best SWR (1.2:1) was at a channel lower than chan 20, which is where the center marker was.

[FurryOne]

I'm guessing it's because a 1/2 wavelength is about 18 feet.

...and for some reason they give you a 13' cable.   

[Paniolo]

Does this look right?

At the head of the CB the antenna cable connects with a mini coax. Inside the tour pack it connects to coil that is bracketed to the corner of the grounding plate. Then a cable with a standard "Crimp on O Ring" type connector comes out of the middle of the coil and is screwed onto the back of the antenna base.

Is all of this correct? 

I'm thinking the only way to get an SWR hooked up is if it has that mini-coax, and attach it at the BB radio unit.

I really appreciate your help guys.

[Coyote]

Put the meter up by the radio. You're going to need TNC adapters like these.

[attach=0]

[Paniolo]

Put the meter up by the radio. You're going to need TNC adapters like these.

[attach=0,msg1288321]

Thanks, does the antenna mounting in the tour pack look correct?

[Coyote]

It's a crappy way to do RF but that's the way they did it back then.

[Paniolo]

It's a crappy way to do RF but that's the way they did it back then.

I guess there's no way to improve it,....LOL??

[FurryOne]

It's a crappy way to do RF but that's the way they did it back then.

I guess there's no way to improve it,....LOL??

Only if you want to change antennas.  If you want 2 antennas that look the same, you're stuck with Harley's CB antenna.

[Paniolo]

Put the meter up by the radio. You're going to need TNC adapters like these.

Okay,

Today I went back to the CB/Ham shop in Oakland. I opened up my fairing and the tech was able to use adapters to go from TNC to what he needed to hook up his meter. He checked the SWR on the antenna, and like many predicted it pegged. After checking it out, his conclusion is that I need to replace the cable that runs from the back of the radio all the way down the length of the bike to the antenna.

He said it was exhibiting a grounding problem. I told him it was a Harley and somewhere along the line I'm sure vibration has caused it to fray, or kink, or ground. I asked what kind of a cable I should get and he suggested the OEM HD one. He said it's most likely built to the radios specifications. I asked if it would be better going to another cable than the MoCo low bid one and he still said no.

Does this all make sense? I'm thinking of buying the HD cable and just hooking it up without installing it along the frame just to test

I appreciate feed back.

Mark

[Coyote]

I would really doubt your cable is bad.

Did he test the cable?   

[Paniolo]

I would really doubt your cable is bad.

Did he test the cable?   

I don't know, how does one test a cable? Do you have to remove it from the bike and hook it up to something,  or can it be done in the harness?

He had me wiggle the connections and ground to look for changes. He had me grab and hold the antenna at the base, and then in the middle and then the tip.

[Coyote]

Well a basic continuity test would be the first thing to do. You would need to disconnect it from the radio to do that.

If the cable is indeed shorted, that would be pretty obvious.

[Paniolo]

Well a basic continuity test would be the first thing to do. You would need to disconnect it from the radio to do that.

If the cable is indeed shorted, that would be pretty obvious.

Good point, I have a multimeter tool and can check the continuity. Would that also tell me if the line is grounded somewhere?

Mark

[Jim Bronson]

I know I'm late to this, but without offending anyone, why do you believe the antenna needs tuning? Is the radio not working as well as it did in the past? Did someone tell you it needs tuning? Just curious.

[PoorUB]

as far as tuning, it is pretty difficult to manufacture a CB and slap on an antenna and have operate at 100%. It is not a point of it being wrong, but tuning the antenna to the proper SWR makes it operate better.

It is like buying a new Harley. You can leave it alone, pour gas in it and ride it, or you can get a proper tune and it will run better.

[Paniolo]

I know I'm late to this, but without offending anyone, why do you believe the antenna needs tuning? Is the radio not working as well as it did in the past? Did someone tell you it needs tuning? Just curious.

I bought the bike used, and the CB has never worked properly. When we are in a staging area and choosing our channels, folks can hear me. But on the road all they hear is garble. So I went to this CB/Ham radio shop to check the SWR. The tech hooked the antenna up to the meter and determined that it was grounding somewhere.  So I thought I'd get another cable and try it.

Mark

[Jim Bronson]

If he means the center conductor of the cable is grounded somewhere, then it may have been pinched somewhere along the run from the radio. Just buy a cable with connectors already installed, and replace it. The SWR of the system can be as high as 2:1, and the radio will work fine, although the radiated power will be less. No need to overthink this. I've never owned a bike with a CB, so I can't say how much of a hassle the cable installation is. Just buy the cable from the ham dealer, and they should be able to help you.

[Paniolo]

If he means the center conductor of the cable is grounded somewhere, then it may have been pinched somewhere along the run from the radio. Just buy a cable with connectors already installed, and replace it. The SWR of the system can be as high as 2:1, and the radio will work fine, although the radiated power will be less. No need to overthink this. I've never owned a bike with a CB, so I can't say how much of a hassle the cable installation is. Just buy the cable from the ham dealer, and they should be able to help you.

Well I found the cable on line for $24 plus shipping. Once I get it I will take it back to the shop, hook it up and have him retest it with the SWR. If it's a good reading, then I'll install it on the bike. If not, then at least I have eliminated one avenue.

Any other suggestions are appreciated.

Once again, the only time I use the CB is in groups when I am either on the point, or tail gunner.
Mark

[Coyote]

2006 was the first year for that CB module and HD had lots of bad ones installed. You should have checked the cable. 

[Paniolo]

2006 was the first year for that CB module and HD had lots of bad ones installed. You should have checked the cable. 

Coyote,

You mean 2006 was the first year for that Harmon-Kardon AM/FM/CB/WeatherBand/CD player unit? And lots of those units were bad? I never heard of this before, but if it's true then I will say screw it, and just not use the CB because everything else works okay. I should get that cable in 7-10 days so we'll see how that goes.

Mark

[Coyote]

There's lots of CB modules on Ebay. Just make sure to get one with a later date code (like 2010). It's only a few mins to swap it out. As I said before, I don't think the cable is your issue.

The common complaint when they first came out was distorted audio.

[Paniolo]

There's lots of CB modules on Ebay. Just make sure to get one with a later date code (like 2010). It's only a few mins to swap it out. As I said before, I don't think the cable is your issue.

The common complaint when they first came out was distorted audio.

You're probably right, but all they guy did was hook up his SWR to the cable that runs to the antenna. He didn't do anything with the radio. And based on his findings, the antenna is bad. It was acting like it was grounded. He said in that condition I could neither transmit nor receive.

[Jim Bronson]

You're on the right track. Have the ham store guy test it with the new cable and go from there. If he used an antenna analyzer instead of the radio as the signal source and the swr is still too high, then the problem lies either in the cable or the antenna or a connection.  They probably used an MFJ 259 analyzer or its equivalent which doesn't require a second box at the antenna feed point. Just unplug the cable from the radio and plug the cable into the analyzer and tune the analyzer to the test frequency and watch for the dip. Good luck.

[Paniolo]

You're on the right track. Have the ham store guy test it with the new cable and go from there. If he used an antenna analyzer instead of the radio as the signal source and the swr is still too high, then the problem lies either in the cable or the antenna or a connection.  They probably used an MFJ 259 analyzer or its equivalent which doesn't require a second box at the antenna feed point. Just unplug the cable from the radio and plug the cable into the analyzer and tune the analyzer to the test frequency and watch for the dip. Good luck.

Getting closer,....

i had him test the new cable, and it read only slightly better than the factory one. Then he had me shake the antenna base and move that cable around. He said the SWR dropped from 30 to 5. Although he would like to see 2 or less, 5 is a lot better than 30. Mind you I have no idea what this means, but I'm taking his word for it.

He suggested replacing the antenna base and coil (part 37 in the attachment) and try again. My only issue is that part number 31 is not listed. How do I order that?

[Coyote]

I would really doubt your cable is bad.

Did he test the cable?   

No surprise there.

Just like the cable, an ohm meter can be used to do a basic check of everything in the antenna system on an HD. You need a better tech to look at your problem.... imo of course.

I'd take all of the antenna components apart and clean all the connections. It's a really simple antenna.