20 Most Recent Cobra LI3900-2DXVP (14 Channels) 2-Way Radio Questions & Answers

Rx is an abbreviation for receive. (Tx is transmit) There are a variety of reasons a radio will be "stuck" in Rx:
1) Another radio in the group is stuck in transmit and you cannot reply if your radio is receiving the other radios transmission.
2) Your radio is programmed for Rx only.
3) Your radio has a Tx problem such as a bad mic, or something covering the mic opening.
4) Your battery is low or bad. It takes more energy to Tx than to Rx.

Best regards.

Cobra... | Answered on Feb 11, 2014


Manufacturer replied to someone that couldn't date models by serial number, but that they began building the model in 1978.

Cobra Radio... | Answered on May 30, 2020

Aquire operation-installation manual from manualslib.com. Mount the antenna on front or side for easy route of coax. Connect red wire to fuse box terminal label ACC or power by ignition. Place power box for best routing of cable to hand unit, under dash, under seat, on left side, etc. Borrow a watt meter to tune SWR of antenna for last step. Happy travels.

Cobra Radio... | Answered on Jan 22, 2020

It is very likely that you haven't got the same CTCSS or DCS codes matched. Try turning them off on both radios.

Cobra Radio... | Answered on Nov 10, 2019

The squelch control is probably damaged. They aren't very sturdy. Controls on radio's these days don't take a lot of abuse. Luckily, the replacement parts can usually be found on EBAY and aren't expensive but you will have to install it yourself or take it to a shop and have it done if you aren't technically inclined. It's not a difficult job to do but a shop will still probably charge more than the radio is worth to do the repair. If you can find a HAM nearby, you might be in luck.

Cobra Radio... | Answered on Nov 10, 2019

It's likely that a bulb has died. This isn't an expensive repair although a radio shop probably won't look at it for at least $75. If you are talking about the display being out, that could be expensive. If the radio is old, then the part probably isn't available anymore. It may be possible to fit something else into the display. I am not familiar with this particular radio. The likely problem is a burnt out series resistor or more likely a bad solder joint on the digital display. THAT should be an easy fix.

Cobra Radio... | Answered on Nov 10, 2019

That's a confusing question. Device id is the FCC device ID number and means it has been approved to transmit in the USA. It has nothing to do with model. So, in terms of a radio device, it means nothing to a tech or a way to get parts or even a battery. The device ID is typically located on the back of a radio or under the battery. Could you ask what you are looking for?

Cobra Radio... | Answered on Oct 04, 2019

Hi Anonymous, as you say, your batteries have little or almost no charge capacity
That's why the charger lights remain on
Simply replace the batteries.
I hope you can solve the problem
Greetings Franco Dosil

Hola Anonimo, por lo que comentas, tus baterias tienen poca o casi nula, capacidad de carga
Espor eso las luces del cargador permanecen prendidas
Simplemente, reemplaza las pilas
Espero puedas resolver el problema
Saludos Franco Dosil


Cobra Radio... | Answered on Sep 26, 2019

the issue is that this radio has an audio boost control function, Dynamike. That is likely the issue, the two are working against each other. You can see if the power mic you have will work if you dial the Dynamike all the way down, but you might have to live with the stock mike.

Cobra Radio... | Answered on Sep 24, 2019

What is the swr? This can impact the receiver. However, the tuning coils for receive and transmit are close to each other and someone most likely turned the receive coil instead of the transmit coil. The coils that are adjustable that affect receive are 13, 15 and 3. 3 is the coil that is close to the transmit section. You may want to have it realigned.

Cobra Radio... | Answered on Sep 13, 2019

If it "keys up" without a mic plugged in, try plugging the mic into the radio and see if it stops. Some radios require the mic to be plugged into it to operate properly. If it is keyed up with the mic plugged into it, try unplugging the mic and see if it stops. If it does stop when you unplug the mic, either the switch in the mic is stuck/went bad or there is a wire shorted in the mic cord to radio plug. Make sure pins 3 and 4 on the mic plug are not shorted. A continuity meter will tell you. If the mic is keyed, pins 3 and 4 will show a short, if the mic is not keyed, pins 3 and 4 should not show a short. If the mic is functioning normally but the radio is still keyed up then there is something in the radio that is shorted.

Cobra Radio... | Answered on Aug 29, 2019

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