Radio Shack Amplified Communication Speaker Model 21-130 Red LED

[JASII]

I bought a Radio Shack Amplified Communication Speaker (Model 21-130) this summer and I have been using it with my Uniden Home Patrol. I noticed that the red LED is lit when their is radio traffic, but sometimes after a period of inactivity the RED led turns off. The manual mentions:

Auto Power Save Circuitry:

The speaker automatically powers off to save energy when it receives no audio signal for 25 seconds.

RadioShack Amplified Communication Speaker : Communication Speakers | RadioShack.com

While saving power is a good thing, I wonder how much power is really being saved by powering off the speaker. I have never had that feature on other amplified speakers, so I just thought it was interesting.

 

[W2NJS]

If the unit is battery powered then the auto shutoff is good to have. If you run the thing from a power supply that is powered by 120 volts AC then the auto shutoff is superfluous.

 

[gewecke]

There is also a useful mod that can be done to the 21-130 speaker to add a switched 2nd output for another speaker to be powered from the same amp.
I've done this mod to mine to add a speaker in another room.

73,
n9zas

 

[jfhtm350]

The one I had would power off and then have a delay in coming back on so you never heard the first part of the transmission and it was very annoying to try to listen to something. Take another scanner if you have one and put them both on the same channel and you will see what I am talking about. I took mine back because of that, but other than that it was a good loud speaker. I saw a mod to disable the power off feature but the circuitry was changed and it has a microprosessor in it now and I didnt see a way to disable anything. As far as saving power, it was hooked up in a truck with the truck running and a 600 cranking amp 12 volt car battery so what is the point of saving power anyways. Never understood that feature.

 

[UPMan]

Note that if you have not done so, you need to add a mono-to-stereo plug adapter to the speaker. Otherwise, the half of the audio amp in the scanner is shorted to ground, which results in non-optimal performance.