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RE: [TowerTalk] Rotor control line switching

Subject: RE: [TowerTalk] Rotor control line switching
From: "Dick Green" <>
Date: Tue, 4 Nov 2003 12:14:48 -0500
List-post: <>

I share a Hy-Gain DCU-1 rotor controller with three Hy-Gain rotors: a
Tailtwister and two Ham IVs. This works pretty well, though the DCU-1 is
calibrated for the Tailtwister and that's not quite right for the Ham IVs.
It's good enough, though. It would be better to use identical rotors. Looks
like you will be using all T2X rotors, so you should be OK.

The remote switch box consists of two sets of DPDT relays, in a cascade
design. Each set of four relays can switch eight lines. The general rule is
that you need n-1 relays, where n is the number of rotors. The first set of
four relays routes the eight control wires to the Tailtwister when in the NC
(normally closed) position (not energized.) When +12VDC is applied to the
first set of relays, the eight control wires are routed to the second set of
four relays. The second set of relays routes the control wires to the first
Ham IV rotor when in the NC position. When +12VDC is applied to the second
set of relays, the control wires are routed to the second Ham IV.

You also need n-1 wires to control the relays, plus ground (in my case:
relay 1, relay 2 and ground.) I was able to use the rotor control wires for
these signals. As it happens, I had already moved the motor capacitor from
the rotor box to the tower, which freed up two control wires. The capacitor
was mounted in a metal utility cabinet that houses all my antenna switches
and lightning protectors. Since the remote relay box was mounted in the same
cabinet, it was a simple matter to connect the motor capacitor directly to
the relays. The relays share the ground return used by the rotor (pin 2, I
think, but check that.)

At the shack end, I build a simple box with a 3-position rotary switch and
some LEDs. Position #1 is no connection (T2X), position #2 is the first Ham
IV and position #3 is the second Ham IV. Position #3 has wires that connect
to positions #1 and #2 through isolation diodes. The box has two connectors
on the back. One is for +12VDC in from my shack DC supply. The other is a
stereo audio jack (two conductors and ground) that connects to a matching
connector I installed on the back of the rotor control box. Inside the
control box, the connector has wires that run to the motor capacitor and
ground pins on the control wire connector. If you don't want to drill a hole
in the back of the rotor controller, you can tap into the control wires
after they leave the rotor control box. If you want to modify the control
box more extensively, you can skip the external switch box and mount the
parts in the rotor controller. You could even put in small regulator to
convert the 24V AC to +12VDC and skip the external connection to the shack

In practice, it works pretty well. Note that the LEDs are essential so that
you know which rotor is connected to the control box!

73, Dick WC1M

> -----Original Message-----
> From: [] 
> Sent: Saturday, November 01, 2003 4:02 PM
> To:
> Subject: [TowerTalk] Rotor control line switching
> I am interested in ways to use a common rotor control box 
> (T2X) with multiple 
> T2X rotors.  A remote switching box would enable me to avoid 
> multiple runs of 
> rotor cable as well as a desk full of rotor control boxes.  I 
> am not aware of 
> anything available commercially, but I may be out of touch.  
> I don't mind 
> building a remote switch box but I would like to do so with a 
> proven design.  
> Your thoughts are appreciated.
> 73,
> Steve, K4FJ


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