6700 MW Reception

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  • Updated 3 years ago
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With the pan adapter on my 6700 opened to several MHz, I see a 30 dB or so peak in the signals from 0.5 to 1.5 MHz with brick wall drops on either side. Is this a design feature of the radio?
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Mark Erbaugh

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Posted 3 years ago

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Stan - VA7NF

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I see the same thing - it's called the AM broadcast band.  My case is slightly different with a BC band filter in LoopA so now there is a dip in signals across this portion.  It also eliminates some front end mixing of 0dbm BC band signals.
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Michael Coslo

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Looks a little like this?
(Edited)
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Tim - W4TME, Customer Experience Manager

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It is all of the RF from the AM broadcast band.
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Stan - VA7NF

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That pattern is not random enough for normal signal reception. 

Your image does not show the signal levels at 1300 and 1400.  If these two signals mix in the 6000 front end or with noise it will present a similar spectrum display.  That is why I have a BC filter inline when in "WIDE" mode in BC/MW range.

Tim, is there a way to handle 0dbm signals without mixing?

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Tim - W4TME, Customer Experience Manager

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Salvador - the answer to your question is no.  When WIDE is disabled, that means a preselector is enabled.  
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Tim - W4TME, Customer Experience Manager

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Mark - there is a lot of RF energy in that particular band segment from the low and high powered AM broadcast stations.  It is a channelized band with no gaps between the channels - just spacing of the adjacent channel stations geographically as to not interfere with each other.  With a very sensitive receiver, this is the effect you get visually when observing the AM BC band.
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EA4GLI - 8P9EH - Salvador

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Thanks Tim. It was more curiosity than a feature request. 
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Tim - W4TME, Customer Experience Manager

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QSL
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Ken - NM9P, Elmer

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Mark.  You can certainly see this effect when you zoom in.  10 kHz spacing with stations with 5 kHz audio (x2=10kHz bandwidth) means the audio sidebands will just touch each other, or even overlap slightly if TX filtering isn't brick-wall, leaving effectively NO space between stations for the signal levels to return to baseline.  Actually the new BCB baseline is the accumulated RF noise of multiple stations on each frequency, even if none of them is strong enough to demodulate.  It is actually somewhat mesmerizing to watch the signals dance on the panadapter at night....if you have nothing better to do!