[Cliffdwellers] QRM on HF

[Walter Cang]

Using an AM receiver, I noticed noise being generated by both radio and switching power supply whenever the receiver is place near either of them.  The QRM disappears if the move the receiver away.

I then used a regular 3 amp power supply and noticed the QRM on the radio is still there.  Assuming a regular power supply does not generate that kind of noise, I assume the source is within the radio itself?  The receiver picks up the strongest QRM when it is positioned above the freq. display and tuning dial.

What can I do about this?  Thanks!

Walter


> -----Original Message-----
> From: cliffdwellers-bounces at mailman.qth.net
> [mailto:cliffdwellers-bounces at mailman.qth.net]On Behalf Of 
> Terry Conboy
> Sent: November 23, 2004 4:36 PM
> To: cliffdwellers at mailman.qth.net
> Subject: RE: [Cliffdwellers] QRM on HF
> 
> 
> At 04:13 PM 2004-11-22, Walter Cang wrote:
> >I checked the radio and it seems that the peak noise level 
> is every 10khz 
> >ending on an 8.  Ex. 14.218, 14.228, 7.008, 7.018, 21.218, 
> 21.228, etc.
> >
> >The sound is heard over a spread of about 2 khz. above and 
> below it.  My 
> >PC is in another room although the loop runs above it in the 
> ceiling.  But 
> >then the sound is still there despite shutting it off so I'd 
> rule that out.
> 
> You may want to try a different receiver and see if your rig 
> itself is the 
> source of the noise.  The frequency displays on some radios 
> emit RFI which 
> is especially noticeable with nearby loop antennas.  The fact 
> that the last 
> "8" digit is involved is quite suspicious, since all of its 
> segments are 
> illuminated.
> 
> My ICOM 765 display puts out noise.  At a previous QTH, it 
> was audible, but 
> not too loud, when I used a 1-wavelength loop antenna with 
> one corner just 
> outside the third floor hamshack window.  (It was connected 
> via a short 300 
> ohm feedline and balanced tuner.)  An AM radio brought near 
> the display was 
> a good sniffer.
> 
> 73, Terry N6RY
> 
> _______________________________________________
> Cliffdwellers mailing list
> Cliffdwellers at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/cliffdwellers
> 


Notice of confidentiality:
The information contained in this e-mail is intended only for the use of the individual or entity named above and may be confidential. Should the reader of this message not be the intended recipient, you are hereby notified that any unauthorized dissemination, distribution or reproduction of this message is strictly prohibited. If you have received this message in error, please advise the sender immediately and destroy the e-mail.