KWS-1: Mystery Solved!

The front “slug rack” mechanism broke during shipping. You can see it had corrosion at the rivet …

The PTO mechanism, which mechanically tunes the KWS-1 has this interesting set of three metal bands. Two raise and lower a tuning “slug rack”, and they have spring tensioners, and the third is connected to the USB / LSB switch.

I decided to take the bottom cover off – just to see if anything was wrong underneath, and the parts just fell out of the top part of the cabinet.

I then used a wooden stick to move the front part of the slug rack up and down, and voila!

Howard, W3HM told me that he has experienced the same thing and fashioned a new one out of sheet brass that he bought at a hobby store and cut with scissors. After you drill the hole – you solder around it so it won’t rip. I looked at the mechanism again – and it actually is 2 little strips – they are bolted onto a small tab that has two little bolts and nuts – and then the other side of each connects to the spring.

You know – this is a 65 year old rig – so I feel I need to know how to fix these sorts of things. You should see how pristine the 75A4 and KWS-1 are – inside and out – Howard did a great job – and I can be proud that my restore of the power supply worked out well.

I took out my trusty digital calipers and found that the brass “foil” is only .1 mm thick. Pretty amazing how something that thin works – but with the springs I guess it doesn’t pull too much on the brass.

I’ve learned a ton so far and even just learning how to use an oscilloscope was a big deal and loads of fun.

3 Comments on “KWS-1: Mystery Solved!

  1. I was lucky to have help online. The antique / vintage ham contingent are a very friendly and helpful bunch – gotta love that! The winner was Bruce, AH0U, (he nailed where the problem was – it wasn’t easy to see just looking around). Bruce me the 75A4, and Bruce was my DXCC card checker back a few years – so its been fun with friends. Its funny how many people are rooting for getting this KWS-1 back on the air – they sure are rare . . . so its an honor

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  2. Great you found the problem. Wish I could magnify the photo you made to see details. Brass sheet is easy to get so that shouldn’t be te problem. 73, Bas

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