SRI-M550 Amplified Speaker
October 28, 2008
October 28, 2008
I bought this amplified communications speaker at a military surplus swap meet. It's a nice little powered speaker which appears to be intended for use with manpack radio sets such as my AN/PRC-70 or AN/PRC-77. It is powered by a 9V battery which fits in a sealed compartment at the bottom of the unit. It is housed in a rugged aluminum chassis, and has a pair of clips on the back which can be used to hang the speaker from one of the "roll bar" handles which are common on these manpack sets.
The top of the speaker includes an audio accessory jack, an on-off-volume knob, a toggle switch which selects analog or digital modes, and a tiny 6-pin auxiliary conenctor made by Hirose. The front of the unit has a speaker grille and a red/green LED. The LED appears to light up green when audio is over some threshold (i.e., functioning as a call light), and red when an attached handset's PTT switch is pressed. White noise will light up the LED, so the radio's built-in squelch function is still necessary to make the call light meaningful.
The permanently attached cable connects to a 5-pin or 6-pin audio accessory jack on the radio. The cable has a 6-pin plug, while the audio accessory jack on the speaker housing just has 5 pins. I don't know yet whether the sixth pin on the cable's plug is connected to anything.
So for, I have not managed to find any information about this speaker on the internet. I'd like to know more about it. What do the analog and digital modes do? What's the auxiliary connector pinout? Are operating and/or repair instructions available? How about a schematic diagram? If you have any more information about this speaker, please contact me.
Here are some more pictures of the unit. Click on the thumbnail images to enlarge them. Note that I added the bar code label on the inside of the battery door; it didn't come with the speaker.
