Topband: Image on 160M

Tom W8JI w8ji at w8ji.com
Mon Aug 13 08:23:20 PDT 2012


Wayne,

Not enough information!!

Any preamplifiers? Any trace of additional modulation?

A mixing of BC signals will have at least a faint second modulation, **and** 
a mixing of BC signals or a harmonic distortion spurious always falls on a 
"ten" in the USA/Canada. It cannot fall on a "five" external to the receiver 
when it is an exclusive AM BCB product.

My Yaesu's are subject to a local AM BC station from an image, and that 
image falls on a "5". Fortunately it is out-of-band.

Unless you have an external signal outside the AM band that is on a 
difference ending in five kHz, or unless the AM transmitter has a spurious 
in some sort of mixing or frequency synthesis scheme, it is nearly certain 
to be a receiver problem.

An attenuation test will only show nonlinearity in the receiver, and it does 
not sound like that is the problem based on the image being on a "5".

73 Tom


----- Original Message ----- 
From: "Wayne Willenberg" <wewill747 at gmail.com>
To: <Topband at contesting.com>
Sent: Monday, August 13, 2012 10:36 AM
Subject: Topband: Image on 160M


> Hello,
>
> As I am slowing working my way into 160M, I have been listening to my
> new reversible 480ft Beverage antenna.
>
> I live in a rural area.  However, there is one small town about 5 miles
> from me.  The only really strong BC station near me is a 500W (day time)
> (not 5,000W) station at 1.490MHz. It is about 7 miles away.  As I tuned
> through the 160M band I found an image of that station at 1.915MHz.  With
> the Beverage, in the *NE position* the image reads -117dBm and if I switch
> to AM mode, I can understand the broadcast. I don't see any other signals
> on the 160M band.
>
> Is it normal to find images like this?
>
> B/T/W, when I switch to the *SW position* (the direction of the 
> transmitter
> and the small town), the signal power rises to -110dBm, but the noise 
> floor
> also goes up.  Is it reasonable to assume the additional noise is probably
> coming from the small town?
>
> Thanks to everyone who has helped me slowly build a 160M station.
>
> 73, Wayne KK6BT
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK 



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