Well, that's not exactly correct either.

Yes, a lower frequency requires a longer antenna. And a 108" whip antenna will provide a good match (SWR) at CB's frequencies (26.965 Mhz for channel 1 to 27.405 Mhz for channel 40).

However, even a 108" whip antenna needs a good ground in order to properly radiate rf signals & w/o that ground won't present a good SWR. So a good place to start will be to ensure the bike's ground system is as good as it can be. Bonding the metal base plate inside the tour pack to the rear frame sub-assembly & then bonding that rear sub frame to the main frame will make a substantial improvement. This approach is what J&M offers with their Part # CBAU-HU14 CB antenna improvement option (although their included replacement coax stub does relatively nothing).

The shorty antenna is actually a spirally wound wire on a fiberglass mast within an outer jacket. Because of this it does resonate at 27 Mhz. If fact, the design is better defined as a "top load" antenna. The oem antenna has no "load" in its' design. I know this as fact because I have used an antenna analyzer to confirm resonant frequencies for both the oem & shorty. The longer oem antenna has a resonance of roughly 25.4 Mhz, while the shorty antenna is resonant at roughly 27.4 Mhz (channel 40 is 27.405 Mhz).

A couple generations back, H-D did use a loading coil in the CB antenna system, but the last 2 iterations of their antenna design has been done w/o any loading coil at all. They also included a 75 ohm Motorola slip fit connector as an inline connector that was located inside the tour pack, but in 2014 was moved outside the tour pack where it is exposed to moisture & subject to corrosion because that connector is not water tight. That's what happens when you put an "EE" idiot with zero knowledge of RF theory in charge of the redesign.

The "properly designed load" that allows a paperclip to look like a good match would most likely be mostly resistive and dissipate the rf signal as heat. But it would not be a properly designed antenna system. So you are correct, the ERP (effective radiated power) would be nil in this example.

Finally, to tie everything together, the junk coax running from the CB to the antenna on the tour pack (that includes the 75 ohm Motorola connector that corrodes when it gets wet) needs to be replaced with a single run of 108" (1/4 wavelength) high quality, well shielded 50 ohm coax.

So while your statements are generally correct in theory, in this case, other issues complicate things.

 

Great write up Hammz - where can i buy single run of 108" (1/4 wavelength) high quality, well shielded 50 ohm coax.?

 

Many years ago, when I put a CB on a bike I had. I took it over to a friends house and he used a SWR meter to check the antenna. We got the antenna cut to the right size that allowed the meter to show the best output of the CB. That is the best way to make sure you get the best performance out of your CB.
Most bikes now come with a general length antenna that will work satisfactorily but then that limits the range of output and reception.
I don't know if any bike shops carry an SWR meter, or call around to friends to see if they know of anyone that has one, but that should be the first thing to check.

 

I bought a Hustler QD-27 Center loaded CB Antenna (55") and an adapter to mount it to my antenna stud and was able to tune it to 1.2 SWR. It definitely helps. I wish I could have the radio power increased.

 

That raises a great question...does anyone know the power output of the HD CB radio? It's not mentioned in the P&A catalog. The FCC legal limit is 5 watts, and I assume if the HD unit was at the max they'd be bragging about it.

 

I have to think that if it was anywhere near 5 watts no one would be here complaining about it.

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For ROCKOUT information & purchasing please click the LINKS below... For all Twin Cams and Evo Big Twins & Sporsters

 

That's exactly what I'm thinking as well. My 4 watt Cobra handheld with the rubber ducky antenna puts out a signal that's just as good, if not better.

 

I seem to recall hearing or reading somewhere that it is either 3 or 3.5 watts.

 

I called Clay's Radio Shop to see if they know, and if they can upgrade it. They have been very helpful to me in the past. I had to leave a voice mail, but I will report back when I hear something.

http://www.claysradioshop.com

 

I've purchased cables from Field Components, Inc.
http://fieldcomponents.com/ custom built 10 foot length with no connector on one end & a male TNC connector on the other end. The CB module is fitted with a female bulkhead TNC connector.

Go to their menu, select the coax builder option & put together your order. I used the standard RG58C/U coax that has a tinned copper center conductor & tinned copper shield, which is very adequate for this application & about 4 times better than the oem junk.

If you want the capability of removing the tour pack, order an 8 foot coax with male TNC & mini UHF female connectors, along with a 2 foot coax with mini UHF male on one end, no connector on the other end.