The stock HD AM/FM/Weather antenna is different from the CB antenna. The base of the antenna indicates which one it is. You should make sure you have the CB antenna mounted in the correct spot (right side) and the other antenna on the left side.

 

If your looking for good tx and rec from the harley cb ,loose the stubby antenna.First off the range on a harley cb is very limited,it will never work as good as a car or truck.Poor ground plane is the culprit and it really can't be made any better.The old ultras came with long whip antennas,my old 98 ultra worked fairly good.My 08 ultra has all metal antennas that are half the length, about 3 foot.Dose not work as good as the 98.My buddy has shorter(about 2 foot)rubber coated antennas on his 09 ultra and his cb works like crap.You could also have damaged the radio by installing the stubby antennas and not checking your swr readings.Continued use of a cb radio with out of whack swr will damage the unit.If you have a cb shop around you i would have them check the radio(they can do it on the bike)if the radio is not damaged put a cb specific antenna on the bike(stock one might be fine)and then have them recheck the swr.if your not sure which mount is the cb,pull the liner up in the trunk and it will be the one with the coil on it.The music radio side will not have it.Its has always been the mount on the right side of the tour pack.Sorry for the long winded post,hope it helps.

 

I guess my first question is, Was it working before the antenna swap?
When was the last time you know it worked?
If you put the old antenna on, does it work?
Do others hear anything at all when PTT is pressed?
Have you done anything else to the bike recently?

You really haven't given us much to work with...

 

Like the others said, Try it with original antenna first. You can damage unit if you remove antenna with cb turned on. I was having same issues, turns out my cb unit was toast. Bought a used one on ebay.

 

Let me expound a bit:

• Poor ground is a problem, but it can be improved: add bonding wires between the tour pack attachment bolts to the rear sub-frame and the main frame will help.
• Current/late model bikes do not have a CB loading coil inside the tour pack. The loading coil was removed somewhere around the '09/'14 time frame. As noted in this photo, the loading coil is shown as part of the 76400-09 CB antenna kit. The OP's '13 model may not have a CB loading coil inside the tour pack.
• If the OP's bike does not have a CB loading coil in the tour pack, the the HD stubby CB antenna (Part Number 76386-09A) will probably work better than the oe whip.

However, this kit's contents has no loading coil included as shown in this included parts list/diagram.

• The side tone the OP hears when he presses the PTT switch & talks indicates the CB radio itself is working, as does the fact he can receive other s' signals. However, the CB's final amp stage could be bad;: this is the possible radio damage referenced in this post.
• The CB antenna is correctly identified as being on the right side, but it might not have a loading coil.
• To check both the "match" (VSWR) and whether the radio final amplifier is good or bad, the front fairing will need to be removed in order to insert an SWR Meter into the coax output cable at the back of the CB antenna. This, as pointed out, is an important step to ensure the antenna system works properly. NOTE - The CB module uses a female bulkhead TNC connector and the attached coax is a male TNC connector. SWR Meters almost always have female UHF (SO239) connectors, so adapters will be needed to insert the meter between the radio's output & the antenna's coax.
• Final point - A competent CB repair shop should be able to replace the CB's final amplifier if it's found to be bad for far less than the cost of a replacement CB radio.