[Cliffdwellers] QRM on HF

[Walter Cang]

Mike,
 
Thanks for the input.  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.  I use an Alinco 30amp switching power supply and I wonder if that is the cause although not likely?
 
Walter
 

	-----Original Message----- 
	From: Mike W. Burger [mailto:mike at gold.chem.hawaii.edu] 
	Sent: Mon 11/22/2004 5:05 PM 
	To: Walter Cang 
	Cc: 
	Subject: Re: [Cliffdwellers] QRM on HF
	
	


	If it is recurrent vs frequency, it should be overtones of a baseband 
	square wave whose frequency is the distance between any two occurances 
	of the tone. 

	In the old days 8^) we used to have dials with crappy analog calibrations. 
	We made square wave oscillators with 100 Khz crystals.  With high speed 
	switching so it made very square corners on the square waves.  Such an 
	oscillator (called a crystal calibrator) when turned on would make a 
	tone at every 100 Khz and go useably all the way up to 30 Mhz if the 
	square waves were really square. (7100, 7200, 7300 etc.)  Thus we 
	could tell how far off the dial was.  Army in world war II had a special 
	set based on this that had a precision dial and a calibration booklet 
	where you could zero beat two of the calibration tones and then interpolate 
	between them to determine any frequency with great accuracy. 

	So if this is the case, the distance between any two tones (all should be 
	the same) will give you the base frequency.  You are then looking for 
	a square wave generator at that frequency such as a switching power supply 
	on a notebook computer (notorious) or one of the fancy new switching 
	power supplies on an Ipod or Ibook etc.  Even the switching power supply 
	sometimes used on the bigger powers USB expansion hubs which have to 
	fork over 3.5 amps in a small case. 



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.