Rf interference messing around my bench supplies. Solutions?

[diydidi]

Hi.
I have some chinese digital readout variable power supplies. Recently I built a little RF transmitter. It operates at around 100Mhz. When I set my power supply for 9V output, and power the little transmitter from it, the digital Led readout goes up to 13V, and the current Led display to 60mA.
If I connect my fluke to the power supply output, it still shows 9V.
So the transmitter is feeding RFI back into my power supply. How do I fix this??
I know it has something to do with chokes, but I don't know much about these.

[AllanK]

Have a look online for Schaffner filters. They are used a lot in industry to stop equipment interfering with each other.

Website:- Schaffner: schaffner.com

Cheers

[doctor]

Line filters are used to prevent transferring interference back to the mains thru power cable. This is not the case.

First of all you need to clarify what is your problem: radiated emission (transmitting interference thru air) or conducted emission (transmitting interference thru cable supplying 9V from power supply to your transmitter). Connect your power supply to a different load having a current consumption of about the transmitter and power the transmitter from the 9V battery.
If the interference presents, this is the case of radiated emission. If no, this is the case of conducted emission. Unfortunately, both interferences may present.

The first remedy against radiated emission is shielding the power supply.

The first cheap remedy against conducted emission is placing ferrite core on the 9V supplying cable as close as possible to the power supply. Exact type of the ferrite can be defined only during special and expensive measurements, but you can try to use the first one, which you can get. See for example: https://www.youtube.com/watch?v=eF6OmKEp37c