[GreenKeys] HAL ST-6000 help needed

[Bob McConnell]

Bob Camp wrote:
> Hi
> 
> Be a little careful when hooking up magnets and keyboards in series on a 
> machine like a 28. On the 15 the keyboard contacts were rated to switch 
> loop current directly. It may have been a bit hard on them but they 
> would do it without obvious damage occurring. On a 28's I have seen the 
> keyboard contacts are not rated for high voltage inductive switching. 
> The magnets are driven off of a separate tube or transistor based driver.
> 
>     Take Care!
> 
>         Bob Camp
>         KB8TQ

A simple check should suffice, at least for all equipment I worked on. 
Look at the contacts, if they are gold plated, they were designed for 
Tempest circuits, a couple of milliamps at 3 volts. If they are not, 
then they should be ok at 60 mA. You might also find some three wire 
setups, as some Tempest equipment used polar switching instead of just 
open/closed. They switched the signal between two voltages, +3 and -3.

Bob McConnell
Ex NFIT TTY
N2SPP