Rotator Lightning protection

The commercial path

Commercial rotor control protection systems must use un-obtainium in their construction or are priced at what the market will bear.

I tend think the latter after asking a few hams who went the commercial route to take a look inside at the components used. Nothing wrong with buying commercial, but a $170 protector for a $390 rotor system does not make sense. So I went about gathering up the parts to make my own.

Parts needed

While the Yaesu G-800SA calls for a 6 wire control cable only 4 wires are actually used, so I selected an appropriate terminal strip and ordered a dozen or so Littlefuse brand MOV’s from Arrow Electronics.

Researching the normal operating potentials I selected a part rated at 25VAC/31VDC and using ring terminals and heat shrink tubing I assembled a suppressor for use at the tower base. The terminal is the highest single point item and I picked this up in the electrical dept of a local big box home improvement store. The MOV’s are 25c each and the tubing and connectors perhaps another buck. All in minus my time less than $5 total investment.

An MOV based lightning protector
An MOV based lightning protector


A simple matter then to fasten and ground the terminal strip in the suppression cabinet. Followed by striping and connectorizing the rotor cable and connecting it to the suppressor.

As MOV failure mode is very visual, they tend to explode when hit really hard, these are rated for 1000A. I should not have any difficulty determining when an event has occurred.

Protector mounted at the tower base.
Protector mounted at the tower base.

Until next time 73’s, Jay



  1. Would there be any value to add gas tube protection in parallel with the MOV’s ? Is there any inherent incompatibility between the two technologies?

  2. Jay –
    You used a MOV rated at 25VAC/31VDC for the Yaesu 800SA which has a rotor voltage of 20vAC.
    What MOV rating would you suggest for the Yaesu g450a which has a rotor voltage of 24VAC?
    73, rick

    • Rick,

      I would consult the Little Fuse MOV product information site for their recommendation. If I recall I sized at a 20% headroom.

      73, Jay

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