[TowerTalk] Yaesu G800 rotators

[Chuck Lewis]

As far as I remember, the brake is on the motor shaft. When the DC motor is energized, the shaft moves axially, pulling the brake disk away from the fixed disk. As soon as the motor drive voltage is dropped, a spring moves the brake disk back into engagement. It's not a HARD brake like a wedge, so it can be defeated, but it's so far up the gear train that there's a lot of mechanical advantage, and it doesn't take much braking action to be effective. A disadvantage, of course, is that any mast torque is still applied to the entire gear train. Because it's a "soft" brake, my G800SDX will move a bit in a hard blow, but not much; and it can easily be reset to the desired azimuth. An advantage of this scheme is that this relatively "soft" braking action reduces any hard transient torque loads at the boom-to-mast interface; so that minimizes the issue of bolt holes being wallowed out by repetitive hard stops against a wedge. I suspect that's the reason Yaesu recommends pinning the mast-to-rotator connection. 

The G800SDX (and presumably the later models) has a ramp-up and ramp-down action in the auto mode, and will coast a little in manual mode, before the brake is applied. Mine has worked very well for many years with no maintenance issues other than moist/conductive insect trash in the connector backshell causing indicator problems. That was easily fixed with a cleaning and addition of plain old Vaseline to fill the void around the electrical connections.      


Chuck, N4NM


  ----- Original Message ----- 
  From: Kelly Taylor 
  To: TowerTalk 
  Sent: Thursday, February 24, 2011 8:59 AM
  Subject: [TowerTalk] Yaesu G800 rotators


  Hi all,

  I wonder if someone can answer this question, because the schematic and the
  manual don¹t seem clear on the issue: is there a mechanical braking system
  of some kind on the G800 or G1000 series of rotators?

  If yes, is there a built-in gentle stop system like the brake delay mod for
  the Ham-IV?

  Thanks

  Kelly
  ve4xt
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