LS-685 Speaker Mods by Al Klase, N3FRQ

     Gang, Most back-pack radios were not designed for loudspeaker operation, but there are a lot of situations where a speaker is a handy addition. Something like an LS-166 will plug right in, but there generally isn't enough audio do make it as loud as you'd like. Plus, the damn thing weighs 3 1/2 pounds. (Just the thing for hand-to-hand combat.)

      Alex, K2AJR showed up with an LS-685 at the recent MTA meet in Northern NJ. He later emailed regarding an E-bay seller who had the two-for-$20, shipped. I ordered a pair immediately. They arrive the other day. This speaker was designed to be used with some component of the Singars family. It's plastic and weighs 1 pound. The connector is wired strangely, and was designed to NOT mate with the standard U-228 we all know and love.

     Disassemble the connector, and move the wire on PIN-E to PIN-B. While the connector is apart, grind away the extra locking lug adjacent to PIN-E. This makes it a U-229 equivalent. The cord on the first speaker I worked on was defective., There had to be some reason the Army threw it away. Connected to a PRC-77, the LS-685's acoustic output measured within a dB or so of my LS-166. However, when connected to my PRC-104 the LS-685 was 10dB louder, a welcome improvement. A quick measurement of the speakers impedance showed 200-300 ohms, versus 600 for the 166. So if the radio has a lower output Z, this speaker will be louder. 6 ounces of the weight of the stock speaker is the heavy shielded coil cord. I went with a lighter cord and cut the total weight to 11 ounces. The speaker has a built-in belt clip on the back, which in turn has a key-hole punch out that can be hooked over a handy screw. I think I like it! Al --

Al Klase - N3FRQ Jersey City, NJ
I posted the following: SJ 18/2 "cord" ( type black, stranded wire size 18, two conductor,) available from your local electrical supply house makes an excellent speaker cord and has a rubber insulation. SJ cord with larger wire sizes make excellent power cords. The white imprinted "cord stamped labels with wire size etc. is easily removed. I usually put a 1 inch section of yellow heat   shrink 3 inches from the end to make it look official.         K4CHE Dover,DE