[600MRG] QEX Noise Canceller

[Marshall Cross]

Yes I agree, as a practical matter, a separate antenna is ok. I was just responding to his statement that seemed to imply that the noise sampling antenna had to be exactly the same as the receiving antenna in terms of its phase and amplitude response vs. el and az angles vs. frequency...........if this were so, then the only way to precisely sample the incident noise field would be to use the actual receiving antenna with a splitter. This is what we did with the Quellen chip with success. Marshall, W1HK

-----Original Message-----
From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of William E. Isakson
Sent: Wednesday, April 01, 2015 2:22 PM
Cc: 600 meter new list
Subject: Re: [600MRG] QEX Noise Canceller

you wrote:
'He made the point that for any noise canceller, the only really effective "noise antenna" is an exact duplicate of your normal receiving antenna'

That is not entirely true.  You can use a different antenna as the secondary antenna and amplify its signal so that it is equivalent to your main antenna.  The MFJ noise canceller, for example, offers 2 input levels for the secondary, one a 10X amplification, and then an attenuator to
equalize the signals.  I can testify that this works.   You are not really
interested in the very low level noise this method might miss anyway.   You
are after major noise sources.

--------


Bill Isakson     AC6QV
Roseburg, Oregon USA
bill.isakson at gmail.com




>>  On Mar 30, 2015, at 12:32 PM, Kenneth G. Gordon <
>>> kgordon2006 at frontier.com> wrote:
>>>
>>>  On 30 Mar 2015 at 8:56, Frank Lotito wrote:
>>>>
>>>> Has anyone tried the noise canceller circuit presented in the Jan / 
>>>> Feb
>>>> 2012
>>>> issue of QEX? Specifically, for the 600 / 630 meter bands?  The 
>>>> article by Fred Brown, W6HPH, is titled "End Man-Made Noise with 
>>>> the Noise Canceller,"
>>>> pages 12
>>>> through 14.  The author alludes to tailoring the design for the 
>>>> frequency band of interest.  The QEX article presents a 75 meter 
>>>> design.
>>>>
>>>> 73 Frank K3DZ / WH2XHA
>>>>
>>>
>>> Frank (and others):
>>>
>>> There was a truly excellent article in Electric Radio Magazine for 
>>> February
>>> 2014 on noise cancellers by Mike Murphy WU2D.
>>>
>>> The final unit he described both reduced his own noise level by +25 
>>> dB and is adaptable, easily, to any band or frequency.
>>>
>>> He made the point that for any noise canceller, the only really 
>>> effective "noise antenna" is an exact duplicate of your normal receiving antenna.
>>>
>>> Mike is quite a character and is very talented. I sometimes wish he 
>>> was a member of this forum.
>>>
>>> Ken W7EKB
>>>
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>>>
>>>
>>>
>>>
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