Hello Jim and others on the list,

Tried various combinations today and the closest to the original voltages was the following:

- One side of 110V connected to shorted 1 and 2.

- The other side of 110V connected to shorted 5 and 6.

A combination of 3 and 4 also worked, but voltages were 15% too high.

As I wrote, I forgot about "half the voltage, double the current", so two primary windings should be in parallel with each other when using 110V in order to balance the current. All's well that ends well. Next step is to see if the rotator still rotates.

73 de Hans

BX2ABT

On 10/21/18 10:24 PM, Jim Sanford wrote:

Try this:

Remove the short from 2 and 5.

Connect 110V to 1 and 2.

Short 3 - 6.

Measure output voltage.  If too low, put power at 4 and 5.

It is possible that this would put 3 - 5 and 4 - 6 in opposite phases.  In which case, you'll have ZERO output.  In this case, short 3 and 4 instead of 3 and 6.  Again try power at 1 and 2 first.

Good luck, and please share results!

73,

Jim

wb4gcs@amsat.org

On 10/21/2018 9:12 AM, Hans BX2ABT wrote:

...

I got this old KR-400 azimuth rotor as a gift, but is wired for 220V and I need to run it off of 110V. The transformer's wiring now looks like this:

|  220V  |      |        | |~~~~|~~~~|   |~~~~|~~~~| 5    1    3   6    2    4 |                  | |__________________|

If the drawing is messed up, here is the gist of it: The primary consists of two (parallel/separate) windings, one with odd, one with even numbering (3-5 and 4-6) with the center of the winding named 1 and 2. Currently 2 and 5 are shorted and 220V comes in at 1 and 6. So current flows from 1 to 5 to 2 to 6 and vice versa.

To rewire to 110V I guess I just use any of the combination 1-3, 1-5, 2-4 or 2-6. But I am just curious why the 220V wiring was done over two coils, not one? Was this factory standard or has my unit been modified with a different transformer?

Once I get the control unit powered up it time to test the rotator and see if it needs any maintenance (probably will, because it hasn't been used for a long while).

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