[TowerTalk] Ameritron RCS-4 question

[TexasRF at aol.com]

Exactly, the point is that three relays are an intuitive means of replacing 
 the rotary switch. I need to learn the art of being more descriptive in  
emails!
 
I am assuming one would bypass the rotary switch and use the three control  
relays to operate the remote relays. The needed blocking capacitors are 
built  into the original control box so it makes sense to retain it just for 
the  convenience of handling the control voltages over the coax.
 
Yes, there are solid state switches that will pass both polarities and one  
could add some led indicators to "see" that the switches are energized. I 
use a  Weeder Technologies board with circuits like that for antenna az/el 
control of  three eme antennas. I still like the audible "click" of a relay 
closing  though.
 
73,
Gerald K5GW
 
 
 
 
 
 
 
In a message dated 9/28/2011 8:30:24 A.M. Central Daylight Time,  
jimlux at earthlink.net writes:

On  9/28/11 6:13 AM, TexasRF at aol.com wrote:
> Hearing and seeing a relay  close is reassuring. That aspect is lost with
> solid state  switches.
> A relay is very tolerant of voltage levels, current, and  polarity. A
> bulletproof device if there ever was such a thing.
>  Use of three relays allows close duplication of the original control
>  circuit. One for +, one for -, one for both and none for the default
>  state. Only one relay at a time needs to be operated making the  control
> logic quite straight forward.


The control box  doesn't have any relays, just a rotary switch.

The box at the antenna  does have relays, but I don't think anyone is 
contemplating changing  that.  There are also multiple versions of the 
RCS-4, for what it's  worth (one has 3 relays in the remote box, the 
other has 2).. but the  control scheme is the same. half wave rectified 
AC as one bit of control,  the other polarity as the other.


There is an advantage of using a  pair of small SPST relays as the 
interface between computer and remote  box, and that has to do with 
providing galvanic isolation. One less place  for a ground loop, etc.

there are some small, cheap solid state relays  that would work, too (or 
optoisolated SCRs)

You'd have to decode  the diode indicators some other way, of course.




> KISS  works for me!
> 73,
> Gerald K5GW
> In a message dated  9/28/2011 7:47:12 A.M. Central Daylight Time,
> jimlux at earthlink.net  writes:
>
>
>
>     You only need 2  relays at most. (at least to actuate the remote 
relays)
>
>   A pair of SCRs? (and some diodes) I haven't had my coffee yet, so  I
>     can't think of how you'd arrange to get them  biased corectly.
>
>     A triac, with the gate  pulse timed right after the zero crossing.
>
>       >
>
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