[South Florida DX Association] N8LP SteppIR Tuning Relay

[Michael Raskin]

If you have a SteppIR, you gotta have this!

The SteppIR Tuning Relay was developed in response to a thread on the 
SteppIR reflector for a way to protect the antenna from damage during tuning 
with high power. FM recommends that you not exceed 200W when the antenna is 
tuning to prevent possible damage. The unit uses current-sensing to trip a 
relay when the SteppIR motors are running.
The unit is placed in the power lead between the SteppIR power supply and 
the SteppIR controller. The principle of operation is that the current being 
supplied from the SteppIR power supply to the SteppIR box is sampled by a 
very low value shunt resistor. The voltage across the shunt resistor is 
compared to a preset level, determined by the sensitivity control. The 
control is adjusted so that the relay is just disengaged when the SteppIR is 
resting and the motors are receiving only a holding current. When any motor 
starts drawing running current, the relay will trip and hold until all 
motors stop running, and the holding current returns. Normally, your rig 
grounds the PTT line to key your linear amplifier. The N8LP Tuning Relay box 
provides isolated relay contacts that are placed in series with the PTT line 
center conductor. The PTT line shield is looped through the box without 
connecting to anything in the box. When the relay opens, the PTT connection 
to ground is broken, preventing the amplifier from keying. Check it out at 
http://www.telepostinc.com/

Brand new unassembled kit as received.  You can buy it from N8LP direct for 
$75 plus shipping, or by mine for $60, which includes shipping.

Mike W4UM