US Signal Corps Collins R388

This is from Josh Brothers, KF4KQS.  He’s a local MARC club member living in Eupora.
So, part of my fun while here in Cartersville, GA for the holiday weekend was to get an old US Signal Corps Collins R388 receiver going to give to another Ham friend in town. This old radio was in pretty good shape other than the dial drum cord being broken.

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That was my job… to figure out how to re-string it so you could tell what band and frequency you were listening to. Well, someone in the past had taken the band switch apart for some reason and didn’t put it back together correctly and got it out of time.

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This is where the pulley on the band switch is SUPPOSED to be when the band switch is all the way clockwise to re-string the drum:

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So, having set the band switch clockwise and loosening the pulley, I had to figure out what to use for new dial cord. I went to the local WalMart and got some 65lb test, braided fishing line to use.
Then I had to remove the pulley from the radio to thread the new line through. The manual says you have to remove the front panel in order to do this, well, I know different. I removed the right three screws holding the front faceplate on and gently twisted a large flat head screwdriver between the faceplate and the radio chassis. Just enough to slide the pulley off the shaft of the switch.

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With the pulley out and the old cord remnants removed I proceeded to feed the new cord into the pulley and tie a large-ish knot into it as to keep the cord from pulling through the hole.

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With the cord in the pulley I then had to feed the cord up through the front of the radio between the faceplate and chassis to the dial drum pulley.

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Then I attached the dial cord to the drum pulley and tied it off. I also took off the spring from the drum pulley so I could pull the cord tight from the bottom of the radio and wind the bottom pulley.

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I had to wrap the dial cord around the pulley about 1 1/2 times to get the system back in time. The original instructions say the 1 1/2 turns goes on the dial drum pulley, but since the band switch mechanism had been disassembled and incorrectly reassembled I had to reverse the turns on the pulleys to compensate. I had tried to do it per the instructions the first time and about halfway through the bands the switching mechanism seized up. I bet that’s what killed the original dial cord.
With the new cord in place it was time to tighten everything back up and put some power to the ol radio.

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She came to life and sounded wonderful. My friend Frank, WA8VRS and I probably sat there and enjoyed listening to some 75 meter AM for well over two hours.

I love boat anchors.

 

Josh Brothers, KF4KQS

3 thoughts on “US Signal Corps Collins R388”

    1. The Collins gear is the Rolls Royce of old ham gear. The prices reflect that too! A pleasure to work on and I was happy to get another one going.

      Like

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