Categories
Ham Radio

Metal work

[Today’s run: nothing]

A few years ago I had made an L/C meter  (Inductance/Capacitance… don’t ask me why they use ‘L’ for inductance) from a plan on the internet by VK3BHR.  The thing works pretty well when I have  a fresh 9 volt battery in it.  I am running the LCD backlight, and it drains a battery pretty fast.  But I’ve been living with that for a few years.

I had mounted it in a plastic box that I picked up at a ham fest.  I don’t really like the box, particularly since I have to open it up frequently to put in a new battery.  Having recently finished a DDS-VFO and gotten it boxed up nicely, I’m thinking I will do the same with the L/C meter.

Somewhere along the line I have accumulated 2-3 of these small size aluminum chassis boxes.  The one I used on the DDS-VFO is 4″ x 6″ x 1-1/2″.  This one I’m looking at for the L/C meter is slightly larger: 5″ x 7″ x 2″.

I use the box as the case and I then have to make a front cover.  I’m going to repeat the process that I used on the DDS-VFO.

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I have a top-cover piece from an old HP frequency counter.  It is a soft aluminum with some sort of textured vinyl coating on it.  On the metal side, I layed out the size I needed by putting the box down and tracing around it with a sharp steel scratch awl.  I then used these yellow-handled snips.  Leaving about half an inch outside of my line, I cut two slices about half an inch apart.  doing that I could alternate sides for each snip and then cut out a slice of aluminum.  I made a half inch wide cut around the 3 sides  (for one side I used the edge of the piece).

After that was cut out I then could use the snips again and carefully slice off most of the fat margin I had left.  By taking just a quarter inch or so at a time I could get it to curl away and not bend up the main piece which I wanted to remain flat.

Then I was down to about an eighth of an inch.  I used a rasp to take that down to the marked line and then touched it up just a bit with the file.  I also filed a couple of strokes on each flat side to ease the edge a bit and to peel back the vinyl just a touch.  I did that procedure on all three of the sides I had marked.  Now I have a nice green vinyl covered piece which fits nicely over my box.

I’ll have to lay out the position for my little LCD screen and a couple of switches, making sure to leave enough room around the margin for the lip of the box, about 3/8ths of an inch.

You can see the end result in my previously posted picture of the DDS-VFO
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