1) Try common mode choke described above
2) You could also try your RFC in the power supply ground lead.
3) Also try a battery instead of the PS.
4) Don't leave any scope probe grounds attached.
All are fixes are for the same thing...
The bottom of your ant loop is attached to the ground (ultimately gnd of the building AC wiring?) of your SE radio unbalancing it.
2) You could also try your RFC in the power supply ground lead.
3) Also try a battery instead of the PS.
4) Don't leave any scope probe grounds attached.
All are fixes are for the same thing...
The bottom of your ant loop is attached to the ground (ultimately gnd of the building AC wiring?) of your SE radio unbalancing it.
Dunno if you tried it already, but have you tried reorienting your antenna? Loop antennas are very directional, you might be pointing right into a null. Also, orientation should usually be with the axis parallel (not perpendicular) to the earth. Move it around before you give up on it.
Thanks Infinia! The common mode choke seems to be the answer to the problem. Do you know why this fixes the problem? I read part of the link from your previous post but it still is not quite clear to me. At least I have a radio that works now without having to touch the antenna. I guess my hand was acting as a common mode choke? Thanks!
Hi Mark
Glad you got your loop working.
Re> common mode choke. It's really called a balun in this application. The real simple explanation is that it’s useful as buffer between a balanced antenna and an unbalanced circuit.
BALUN = BALance + UNbalanced
It’s also used to keep the transmission line from unduly interacting with the antenna and possibly re-radiating the EM energy collected. Google antenna and balun for more indepth discussion.
edit>
Another way to look at it
The balun choke looks like a large inductance for currents traveling down both conductors (common mode). And looks like a low inductance for differential currents ie balanced currents returning to and from the source (they cancel each others magnetic field in the core).
Glad you got your loop working.
Re> common mode choke. It's really called a balun in this application. The real simple explanation is that it’s useful as buffer between a balanced antenna and an unbalanced circuit.
BALUN = BALance + UNbalanced
It’s also used to keep the transmission line from unduly interacting with the antenna and possibly re-radiating the EM energy collected. Google antenna and balun for more indepth discussion.
edit>
Another way to look at it
The balun choke looks like a large inductance for currents traveling down both conductors (common mode). And looks like a low inductance for differential currents ie balanced currents returning to and from the source (they cancel each others magnetic field in the core).
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