[MRCA] Loudspeaker, Crystal LS-685/U

Al Klase ark at ar88.net
Thu May 10 14:57:16 EDT 2012


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 make 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
http://www.skywaves.ar88.net/



More information about the MRCA mailing list