[Top] [All Lists]

[TowerTalk] Remote LM-470

Subject: [TowerTalk] Remote LM-470
Date: Thu, 14 Sep 2006 19:54:15 EDT
List-post: <>
You can easily design a remote control system without the 5 sec delay  
devices. but you have to remember not to switch from up to down (visa  versa) 
quickly as motors with centrifical start switches have a bad habit of  not 
changing their direction of rotation.  The "glass" delay switches are  
easy to find (with short delays) and quite reliable.  There are  solid state 
types, but one has to be careful to make sure the delay relay  control circuit 
is understood and the control function will work.  The  control remote control 
box consists of a up relay, and a down relay, interlocked  with remote limit 
switches.  In addition there is usually a Main Relay to  supply power to the 
motor, and the up down relays only control the polarity of  the START winding.  
A transformer to supply 24vac for relay operation is a  must or you will be 
running 115vac to the limit switches, (not a good  idea).  Then you need a main 
ON/OFF switch (control the main relay) and a  double pole, center off switch 
to select the proper relay. And you need to delay  the application of voltage 
to the UP/DWN relays to assure motor decay and proper  direction of rotation.  
The thermal activated delay relays (glass) are simplicity at work, apply  the 
power and 5 seconds later the contact closes, and this SAME power source  
also activates the control relay.  The solid state relays require a control  
and the power line.  Many of the solid state devices found in surplus  are 
Delay on OFF, that is remove "control" voltage and the count down  starts.  
The other advantage of the "tube" type is the failure mode (heater opens)  is 
a SAFE mode in that the relay won't operate.  That may not be the case  with 
solid state device unless you think through the control circuit and make  
failure mode analysis.
A long winded discussion, but remote control is pretty straight forward yet  
has pitfalls.  The requirements can be modified depending on how much  "fool 
proofing" you want to design in.
Good luck,
Norm W4QN
In a message dated 9/14/2006 4:34:05 P.M. Eastern Daylight Time, writes:
From: "Bill Erickson" _ericksonw@gmail.com_ ( 

I have a Tri-Ex  LM-470 motorized crank up tower. I would like to be able to
remotely control  it from my ham shack. The only remote control system that I
have been able to  find is the original system that was offered by Tri-Ex. My
concern with that  system is that it uses (GASP) vacuum tubes to provide the
delay required when  changing directions. Does anyone out there have a
schematic or other  information on a more modern design? I have the
facilities to fabricate  anything needed, or I would be willing to purchase
an existing system. Any  suggestions?

Thanks for your  help.
Bill       N6MXU

Norm W4QN

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>
  • [TowerTalk] Remote LM-470, NPAlex <=