[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/
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