[TowerTalk] Relays for motorized MA770

[Dick Green WC1M]

No, I don't see any reason why you shouldn't use 24VAC relays, provided  the
relay contacts are rated for 110VAC and the current drawn by the motor (I
don't recall offhand how much current is drawn.)

FWIW, the stock remote control system for  the MA770 uses 110VAC relays.
IMHO, this is a bad idea. It means you can't run the relay control cables in
the same conduit with low voltage control cables (forbidden by most building
codes.) It also means there's 110VAC on all the switches and indicator
lights in the shack control box.

For these reasons, I built an interface to the 110VAC system using 12VDC
relays mounted in a box in the remote control cabinet attached to the tower.
The control cables run in a conduit with other low-voltage control cables
for the tower. My control box in the shack uses 12VDC signals to activate
the 12VDC relays, which in turn activate the stock 110VAC relays. The
control box uses low-voltage LEDs instead of the 110VAC neon lights used by
the stock control box. It's about 1/6 the size of the stock control box,
too.

Note that the stock remote control system uses limit switches and a time
delay circuit to prevent sudden change in direction.

73, Dick WC1M

> -----Original Message-----
> From: K6QD [mailto:k6qd at cox.net]
> Sent: Monday, March 02, 2009 3:51 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Relays for motorized MA770
> 
> I am building a new control box for an old motorized MA770 tower for a
> friend.  I want to include provision for remote control and designed the
box
> with 24VDC relays.  I happen to have some nice 24VAC relays.  Does anyone
> see a downside to using the AC relays vs. the DC relays for this app?.  I
> also save a 24V PS and just need a 24V transformer.
> 
> Tks es 73 de
> 
> Mike K6QD
> 
> 
>