LS-454/U Loudspeaker

Background

Internally it uses the same blast proof speaker as the LS-166 and many other military speakers.  It was intended for use on the VRC-12 series radio systems, or with the AN/VIC-1 Intercom system.  For use with most mil radios the U-229 plug needs to be rewired.

Trivia

Note that on a SSB HF radio  you can not use the PTT line on the U-229 connector for the CW keying line since there would be no carrier because there would be no modulation.  So these radios use pin "E" as the CW keying line that both turns on the transmitter (like the PTT pin "C") and also adds an audio tone.  So if you connect a stock LS-454 to a SSB HF radio it will key the radio in CW mode.
Thanks to Ira on the Army Radios mailing list

Maintenance Information

Two wires are connected between the connector and the primary of a 600 Ohm to 8 Ohm transformer.  Black from pin "A" and white from pin "E".  This is a non standard wiring for the U-229 connector which would normally use pin "B" for an earphone or speaker.  The speaker in my unit was made by ADEC, Inc. Farifield, NJ and is marked LS-445  6326-A6-6B the last two characters are hard to read.

The lid is also marked AMER. DEV. ELECTR. CO.   202-5.  My unit was new in the sealed foil wrap and yet does not have any gasket between the lid and speaker body.

The DC resistance between pins A and E is 23.5 Ohms and is due to the input transformer.

Manual

Modification

To use this speaker with the modern radios like the PRC-68 Family (need to also use a "Y" cable)so that you can also use a mike like the M-80. Radios with 2 AUDIO connectors like the PRC-25, PRC-77 don't need the "Y" cable.

In any case the hot speaker lead needs to be changed from pin "E" to the standard pin "B" inside the U-229 connector.

This can be done by:

• Unscrew the nut holding the Cable Strain Relief and slide it back
• Unscrew the black U-229 end cap and push out the blue block holding the 5 electrical contacts.
• Slide the black cap back along the cable
• Slide the sleeve back exposing the back side of the connector block
• Unplug the pin from the back of pin "E" and plug it into pin "B"
• Slide the blue connector block back into the U-229 shell.

This is tricky because you need to align the two tabs with the two notches in the shell to get the block fully seated.
• slide the sleeve forward and put the knot into the slot on the sleeve
• Screw in the black end cap
• Screw in the cable strain relief nut
• Label LS-454 "Pins A & B active

A PRC-126 now has room filling audio volume.

Mounting Bracket

 


I saw this one on Mike Murphy's web page
LS speakere Mounting kit

This mount would work for all the speakers that have the threaded rod on top like the LS-166.

Note the hole for the LS-454 threaded rod has flats to prevent the speaker from rotating.

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