CDE rotator scale: refit for North center

Redesigning CDE Rotator Control Meter Scale for North-Centered Operation

Originally published April 8, 2007 — Updated Nov. 2013

When I installed my MA-40 MARB rotating tower in Sept. 2004, the CDE rotator control box had a south-centered scale. I never thought about that till this week. Then, while looking at ads in CQ Magazine, I suddenly realized that changing to a north-centered scale would greatly reduce the turning required to work JA – EU – W/VE.

The original south-centered meter scale that came with my CDE rotator control Box.

Some CDE meter scale backplates have reversible North or South sides. Mine did not. Imagine my disappointment upon opening it up.

So, I had to make my own. I scanned the south-center scale as a 2400-dpi image and used desktop publishing software to create new bearing numbers along the arc lines, and S-W-N-E-S indications. Use any software that allows you to make and rotate text boxes.

The redesigned north-centered meter scale.

I tried various applications to create an arc line and add the text of all bearings to that line, but found it was simpler and more accurate to make individual text boxes, positioning them in the right place and rotating them.

While I was at it, I added ZL VK JA EU AF W SA labels to the appropriate bearings for a custom job. Took three hours to meticulously redesign the meter scale. I like the results very much, and readability is vastly improved.

I printed the new meter scale on white paper and glued it to the “blank” side of the plate. Getting the meter back into the CDE box is a challenge, but take your time with the spring-retained clips and it will work.

For me, re-aligning the tower was as simple as loosening the tower in the rotator’s jaws at ground-level, turning the rotator to due south (through W>SW>S), then hand-turning the tower due south and tightening everything up. Spot-on alignment.

Hope this helps someone else convert their CDE Rotator Control Box from south to north centered operation, or vice versa.

Downloadable image — NORTH-centered scale (Updated April 2011)

Download this meter scale as a very large .JPG (2.45MB)

The downloadable file is a large 2400-dpi .JPG image of the north-centered meter scale, placed on the full-size meter plate. This version is improved from the first attempt, with better placement of the numerals. The ZL, VK, JA, etc. labels have been removed, allowing you to place your own geographic labels appropriate to your own great circle bearings.

It’s ready to print — though you may need to place the image in a Word document or other image-handling software to resize before printing, depending on your setup.

Downloadable image — SOUTH-centered scale (Updated Nov. 2013)

Download this meter scale as a very large .JPG (1.92MB)

For those who need a South-center version of this customized meter scale, the link above will provide that high-resolution image suitable for printing.

Steps to opening the CDE rotator control box:

(Note: these instructions are a general guide and are not intended to replace the instructions provided in your CDE Rotator Control box manual. Always follow the manufacturer’s instructions. Failure to exercise appropriate safety precautions could damage you, your control box, the meter movement, or other things, such as your self-esteem.)

  1. Remove screws from sides of the box, and remove top and bottom covers of the box.
  2. Loosen the nut on the lamp support (it’s a metal bar that goes from the side of the transformer to the front of the box, above the meter), then slide the lamp out of the way.
  3. Remove the nuts from the two terminal posts on the back of the meter. There’s not a lot of room for fingers to work in there, but it will work. The manual recommends temporarily connecting the posts together with a bit of wire to prevent damage to the meter (from stray static charges, for example).
  4. Pull the circuit board off the two terminal posts.
  5. Push the circuit board down through the hole so it’s underneath the chassis. This give you clearance to remove the meter from its holder.
  6. Carefully push the two brass clips so they release the meter. The meter will then be loose in its tracks and can be slid up and out. The clips are held fast by springs, but can be pushed forward so their ends release the meter. (You’ll know what I mean when you get in there).
  7. Using a thin blade, you can pry off the clear cover of the meter. Be VERY CAREFUL not to touch the needle or its movement. It is EXTREMELY sensitive to even the slightest breath of air.
  8. Using a thin blade, carefully work loose the meter scale metal backplate. It has two holes that align with indexing pins on the meter housing. Once the plate is clear of the pins, you can remove the plate — taking care not to damage the needle as you slide the plate out.
  9. If the back of the plate has the opposite (north-centered or south-centered) scale, you can just flip it over and reinstall it. Some models of the CDE controllers have these reversible plates.If the back of the plate is blank (it’ll be a bare metal finish) you can now glue on your replacement meter scale. The thickness of your paper sheet may actually cause the needle to jam where it comes closest to the metal plate. To prevent this jamming, ensure that the paper is trimmed so it is no closer than 0.25 inch (0.5 cm) from the semi-circular cutout on the meter plate. This gives plenty of clearance for the needle.
  10. Reinstall everything, and you’re done.

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