Topic: New station on-line, but noise issue

[dfroula]

Jim in Mauston, WI received the station I built and has it on-line. However, he is seeing a severe noise issue that is driving his station into periodic interference mode and otherwise severely reducing the auto-adjusted amp gains. I've attached a picture of the noise.

The pulses are continuous and vary somewhat in frequency between 10 KHz and 12 KHz or so. The noise signals from both channels are always perfectly in-phase. Only the amplitudes vary as the amps readjust their gain due to the auto-adjust algorithm. The noise remains constant regardless of station location in the house or antenna orientation. Lightning waveforms that make it through the noise and low gain look perfectly normal.

My bet is on a noisy 5v power supply used to power the system. Any other thoughts?

Thanks and regards,

Don

[miraculon]

One thing you could try is making a steel shield for each antenna. I used a 1 1/4" (double check this diameter) steel pipe section with a cap that was just long enough to cover the antenna. With the pipe shields in place, it will tell you whether the noise is referred to the antennas, or is back-way (via power, grounding, etc). If the noise disappears with the antennas shielded, then the rest of the system is OK and it really is getting into the antennas alone. Of course, this is just a test. It eliminates the desired lightning signal along with the noise.

I found that my noise floor on my 6.8USB system was quite good and all the noise was being picked up by the antennas.

It might help isolate the problem.

Greg

[dfroula]

Good idea!

The ferrites are already in shielded tubes using aluminum tape with a narrow longitudinal gap. Perhaps wrapping some aluminum foil temporarily around the tubes, bridging the gap, would achieve the same thing.

The station hardware was outperforming my own station here in Chicago, so the basic hardware should be fine. Jim's using a locally obtained power supply.

Don

[Cutty Sark Sailor]

Good idea!

The ferrites are already in shielded tubes using aluminum tape with a narrow longitudinal gap. Perhaps wrapping some aluminum foil temporarily around the tubes, bridging the gap, would achieve the same thing.

The station hardware was outperforming my own station here in Chicago, so the basic hardware should be fine. Jim's using a locally obtained power supply.

Don

The aluminum won't block the near E-field...  That noise may also be from a computer... 

[W3DRM]

Is he using a different 5v power source than what you used when you built the system? Could be a bad ground too. Is his antenna and amplifier located away from the controller board and especially away from any computers he may have. Any electric fences around his area?

[miraculon]

Good idea!

The ferrites are already in shielded tubes using aluminum tape with a narrow longitudinal gap. Perhaps wrapping some aluminum foil temporarily around the tubes, bridging the gap, would achieve the same thing.

The station hardware was outperforming my own station here in Chicago, so the basic hardware should be fine. Jim's using a locally obtained power supply.

Don

Don,

It needs to be ferrous material. As Cutty said, it will only block the e-field. It will also create a shorted turn, leaving only leakage inductance.

If he can't do the pipes, maybe some soup cans with both ends cut off (will they fit ) and placed end-to-end might work. They are steel (still?) I think. The pipe nipple and cap was just a matter of a run to Home Depot and a few bucks...

Greg

[Cutty Sark Sailor]

Good idea!

The ferrites are already in shielded tubes using aluminum tape with a narrow longitudinal gap. Perhaps wrapping some aluminum foil temporarily around the tubes, bridging the gap, would achieve the same thing.

The station hardware was outperforming my own station here in Chicago, so the basic hardware should be fine. Jim's using a locally obtained power supply.

Don

Don,

It needs to be ferrous material. As Cutty said, it will only block the e-field. It will also create a shorted turn, leaving only leakage inductance.

If he can't do the pipes, maybe some soup cans with both ends cut off (will they fit ) and placed end-to-end might work. They are steel (still?) I think. The pipe nipple and cap was just a matter of a run to Home Depot and a few bucks...

Greg

Thanks for the tact, Greg.. my post should have read 'H-field'...    ...one of those days...
He might also try the 'AM radio' trick...

Mike

[dfroula]

Yep, that makes sense. Had a brain fade on that for a moment.

Thanks for clarifying!

Don

Good idea!

The ferrites are already in shielded tubes using aluminum tape with a narrow longitudinal gap. Perhaps wrapping some aluminum foil temporarily around the tubes, bridging the gap, would achieve the same thing.

The station hardware was outperforming my own station here in Chicago, so the basic hardware should be fine. Jim's using a locally obtained power supply.

Don

Don,

It needs to be ferrous material. As Cutty said, it will only block the e-field. It will also create a shorted turn, leaving only leakage inductance.

If he can't do the pipes, maybe some soup cans with both ends cut off (will they fit ) and placed end-to-end might work. They are steel (still?) I think. The pipe nipple and cap was just a matter of a run to Home Depot and a few bucks...

Greg

[Cutty Sark Sailor]

Yep, that makes sense. Had a brain fade on that for a moment.

Thanks for clarifying!

Sigh... . I wish my brain fades were momentary...

[jmcmurry]

Swapping out the power supply didn't help, but grounding the controller ended up fixing the problem.  Now the system is performing great!  Thanks Don for getting me up and running on the network.   

- Jim

[DaleReid]

Thank goodness the Alien Factor didn't need to be invoked.

Great job on the station.  Those nasty lightning strikes will be here soon.