Question re Interference Symptoms

[ashart]

I receive unmodulated carriers, near or above S9, about every 30 Kcs from about 1.7mhz to about 7mhz.  They may be lower than 1.7mhz, but my receiver doesn't go down there.

The carriers are interfering with my work on the receiver.

Shutting down my entire house other than the workshop and shutting down everything in the workshop other than the receiver, does not kill them.

I don't think they're birdies, because disconnecting the receiver's antenna kills the signals.

Is this possibly some form of cable leakage?

All relevant ideas welcome, and thanks!


-al h. w8vr

[ke7trp]

Yes.  Get a small battery powered SW Radio. Tune to the signal. Put the radio in CW or SSB so you can hear hetrodyne (easier to hear).  Start walking around with the thing. If you cant hear the signals then Clip lead your antenna to the SW radio, Tune it to the signals. Then disconnect and talk a walk around the hood.  I have done this many times.  Its probably a neighbor with some gear running.  Pool pumps is a big cause of noise here as are roof mounted heat pumps.

C   

[k4kyv]

Cable modems can cause that type of interference, too.  But it seems to get stronger the higher you go in frequency.  My old one wiped out 10m and was audible down to 40m. The new one spews out less, but some garbage is still there.

[Tom WA3KLR]

Sounds like a switching power supply.  
They run at 30 kHz to 100 kHz typically.

[ke7trp]

Yes. The Astron 25 amp switching supply has a Full scale signal right on 3870. Complete garbage. 

C