>Date: Sat, 09 Jan 1999 06:27:53 -0500 (EST)
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>From: "SM6EHY" <firstname.lastname@example.org>
>To: "'TOP BAND mail'" <email@example.com>
>Subject: TopBand: Re.:BC Hash
>Date: Sat, 9 Jan 1999 12:27:36 +0100
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>I've gotten some input but I'm still asking for help from anyone who
>hears BC hash around 1830, in particular if they hear it really strong.
Hi, what I understand this is an example of RX-overload.
The programs are transmitted on 1310 & 1140 kHz.
Of this mix we have the difference of 170 kHz.
1st mix product is 1480 kHz; 2nd is 1650 kHz and 3rd is 1820 kHz.
As we know from before, the odd multiples are the strongest, which means
that the ones on 1480 and 1820 can be significant.
When the program is modulated on voice peaks, it causes splatter on 1830 kHz.
I suggest You can use a HighPass filter in Your Rx, with a design QRG of
some 1750 kHz.
We have here in Eu an example of such a mixing, but originating from another
cause. The case here is that on the VERY SAME transmitter site, T W O
transmitters broadcast the same program on nearby QRGs, but in different
directions. From this site we can (all of us...!!) hear the 1st, 3rd and
5th mixing product. This is due to some ARCING OVER between radial wires
OR direct radiation from one TX to the other. This is easily detected on a
spectrum analyzer at the TX site. Fortunately this takes place OUTSIDE of
the HAM bands (in Eu). The site is located in Russia and transmits on
the BC 40mb. Only on rare occations we can hear traces of this on 7070 kHz.
73 de SM6EHY
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