Can high power RF equipment damage nearby devices ?

I got a cheap transmitter from china and after a few minutes of use on the 2-meter band at 10watts of power my wifi router dropped connection and the lights started to flash (now it doesn’t power up). Not thinking this was related I plugged in a different wireless router and 30mins later the wifi on it too has dropped out and would not connect, even after I had turned off the new transmitter.

Also later that night our 2.4ghz cable tv signal transmitter has completely stopped working…

Is this just a strange coincidence or is it possible to damage nearby RF equipment with just 10watts of power ?

Yes, it is. If the equipment isn't sufficiently bypassed, or if you are operating close to the wires (power or ethernet), it is possible.

The wifi routers and the cables were about 2m away and the 2.4ghz cable transmitter was in the next room

Your “cheap” transmitter could have been pumping out many tens of watts in a wide spectrum of frequencies.
Basically what you have is a wire-free gizmo destructor.

Or it could be entirely co-incidental. Have you tried turning them all off and back on again?

jackrae:
Your “cheap” transmitter could have been pumping out many tens of watts in a wide spectrum of frequencies.
Basically what you have is a wire-free gizmo destructor.

No way! - its hard enough to get 10W from RF transistors in the first place, there certainly isn’t “many tens of watts”
available for anything else, and a cheap transmitter would not be using over-specced RF power devices, they cost…
(Speaking as someone who has built transistor and valve VHF transmitters). The spurious emissions from a 10W
transmitter would be small compared to what a mobile phone can generate, for instance. Its the 10W in-band
that is doing the damage.

If you set up a transmitting station and don’t pay attention to antenna / ground placement you are asking to
fry delicate electronics.

With only 10W just having a reasonable spacing from antenna to house wiring might be all that’s needed.
10W into 50ohms is 22V rms, but at the ends of the antenna wires the impedance is effectively a lot higher, and
voltages will be in the hundreds - thus the need for good spacing between antenna and sensitive circuitry, or good
grounding/screening around the sensitive electronics. Antennas need to be several wavelengths away from other
bits of metal anyway.

I know that people designing ship-board receivers used 10W MOSFET's in the front end because of all the power amplifiers hooked up to the mast. If could be that you blew out the frontend of the router. You might have to design a band pass filter for the antenna connection on the router, unless you have no accesible antenna.