I am interested in the Velleman P8023R/S system but need the power input to be on the transmitter instead of the receiver. Is there a system with this configuration? Has anyone successfully modified the boards to accomplish that… I want to control an antenna from my hamshack. I am also considering the Rookey system but prefer the Velleman system.
Jim
K4AHO
[quote=“jwd”]I am interested in the Velleman P8023R/S system but need the power input to be on the transmitter instead of the receiver. Is there a system with this configuration? Has anyone successfully modified the boards to accomplish that… I want to control an antenna from my hamshack. I am also considering the Rookey system but prefer the Velleman system.
Jim
K4AHO[/quote]
I assume you want to drive a motor to rotate a dipole or Yagi. I don’t have a P8023, but I can read schematics to a degree.
vellemanusa.com/downloads/0/ … _k8023.pdf pages 15 and 16.
First keep in mind that the outputs on the P8023 are routed through ULN2003 darlington transistor arrays. That means they are open collector outputs that can switch up to 500mA. You might need a relay or at least a MOS-FET.
Now to the schematics. Transistor T2 on the transmitter side is used to modulate the control signal onto the supply voltage by altering the transmitters resistance. That signal is decoded on the receiver side using transistor T1. The complete transmitter and resistor R15 build a voltage divider, which drives T1. For this reason, the transmitter and receiver do not share a common ground. In fact, the transmitter isn’t connected to GND at all. It uses the VTX- line as GND2.
To move the power input from the receiver to the transmitter you would move/copy everything between the 12…15V connector to the regulator VR1 over to the other side. Connecting Vout to the VTX+ line on the other side should not make any difference. That will require to use a 3 wire connection, because you need have GND separate on the receiver side. Do not short GND to GND2, or communication will be impossible.
So yes, with a 3-wire connection, feeding stabilized 10V with enough Amps into it and using motor(s), that run off of 10V, that should be possible.
73, WI3CK
ETA: I recently finished building my Juma TRX2-A and a Hustler 4-BTV. So I can do 10 Watts CW/SSB on 40m. I’ll be listening for your callsign.