Transmits but does not Receive

The static tells me that your audio chip is working, but the stages ahead of that are not feeding a signal to the audio amplifier. The intermittent receive sounds like a bad antenna connection, or bad contacts on your transmit - receive circuits. I don't know the Cobra 29 LXBT circuitry, but likely a relay is switching between transmit and receive when you press the mic key. You could try connecting your antenna to the pins on the relay that carry the rf signal to the receiver circuitry. If you suddenly starting picking up signals, you know the switch is the problem, as you have by passed the switch momentarily. Don't try to transmit in this condition.

Check coax continuity with a VOM/ continuity tester. Make sure the braid and center conductor aren't touching. OR, put the radio on an antenna system that is known to be working and see if receive works. If after these tests you still don't hear anything, You may need to talk to a repair technician.

Simrad RS82. Ok, can you switch to 1 watt and see if it transmits on low power? If it does, check all wiring and your power source (battery or power supply) for enough voltage. Marine radios often get corrosion on connections. Later, check your external antenna and connectors. Of course, you can never transmit on the pre programmed weather channels.

Sounds like a bad receiver in the radio.
Have you checked the VSWR of you antenna system?
Did it ever work with the current setup?
If so has anything changed with the programming of the radio or the antenna system?
Does 70cm work OK?
Are you sure menu item 080 is set to "SQL" and not "RF-GAIN"?
Are you sure the receiver is not programmed for tone squelch?
Either of those settings could cause receive problems if not used properly.

Most problems with radios that receive but do not transmit are antenna or antenna wire/connector issues. It's easy to receive with a marginal antenna but transmitting requires a good working antenna. If you have a SWR meter or can get your hands on one, install it in line with the antenna and test for reflected power. Of course, make sure your TX light comes on when you depress the mic switch. If not, switch mic and try again.
Hope this is helpful! Reply if u can.

Your finals are fried. Take it to a shop and they will fix the finals. Before you do that be sure to put in an extension speaker just to be sure. Most CB shops are inexpensive.

Try changing out the squelch controll, (#BRVG0925001) this should do the job. Good luck.

set the antenna and SWR to match that should give you better distance

I don't have much experience of radio transceivers but I do have a couple of ideas.

The big question is how do you know your radio transmits 30 miles but receives only 6 miles?
Clearly you have a friend with a transceiver and you have been playing around together until you formed those conclusions.

What if the other radio received well but didn't transmit so well? Have both radios been checked with a field strength meter to ensure they are both radiating similar power outputs?

Do you receive the carrier wave but no audio at a range greater than 6 miles? If so your friend's radio (and others) might have a modulation problem. Has the signal(s) been analysed with an oscilloscope?

It is often imagined the transmission envelope is circular radiating from the antenna at the centre but that is often wrong. The radiation envelope is often distorted by a ground plane. Imagine an antenna mounted at the centre of an aluminium boat hull, the radiation envelope would be elliptical in line with the hull.

Even with a fibreglass hull the presence of metal masses can pull the radiation envelope out of shape lengthening the range of both transmission and receiving in one direction and shortening them in another.

There is another possibility to poor reception and that is a high amount of interference that might be airborne being received by the internal radio circuitry, by several means - antenna or the poor screening of the downlead and could be aggravated by poor grounding. Interference can also be on the supply line and both types can be generated by a host of electrical or electronic equipment.
Generators and motors, voltage regulators or stabilisers, local oscillators, fluorescent lighting, inverters, computers...

The basic radio of the old days could have the Squelch turned off and an experienced operator can hear much of what is or isn't happening.