Are your filters okay?
 

Monkey chatter leaking in from adjacent stations is the bane of the
radio listener. It is most annoying and can badly interfere with the
station you are trying to listen to. As radio's have got better over
the years by using better circuitry and better filters, this problem
is not as bad as it used to be many years ago.

But it is still a problem, especially on cheaper portables. In the
$100 price range, don't expect wonders, as even the Chinese
manufacturers have to compromise quality and build DOWN to a budget
price. My current best portable is my Redsun RP2100 (CC Crane SW &
Kaito KA2100). It has a narrow and wide filter setting - narrow is
about 10 kHz wide and "wide" is as broad as the sunny skies in mid
summer. So it does let in monkey chatter from adjacent stations. This
is because the ITU lays down a 5 kHz channel separation and unless you
have a radio with top end circuitry and tight 5 kHz filters, then the
adjacent channel is bound to break through.

A top of the range portable like the Eton E1 has excellent filters
(see Passport review) and will do a very good job of keeping the
monkey chatter out of your desired signal. Top end tabletop
communications receivers are even better. The more you pay the more
you get. This makes general listening a lot more pleasurable and
satisfying.

But even with these top end radio's you may still get annoying monkey
chatter and wonder why, and wonder if your radio has gone on the blink
and if the filters are not working properly?

The answer is NO, it is not your radio but badly adjusted transmitters
spewing out splatter by way of a bad footprint and harmonics and
artefacts. A transmitter is supposed to occupy no more than the 5 kHz
assigned to it by the regulating authority, but with the advent of
radio's with spectrum scopes it is possible to see exactly how much
space a transmitter is occupying. A lot of them occupy 10 kHz and some
even as much as 12 kHz. In one case: BBC Meyerton on 3255 kHz it was
actually splattering 40 kHz above and 20 kHz below it's assigned
frequency. Even if you have a $10,000 receiver like the Icom IC-R9500
you still won't get rid of that.

Another example is 6150 kHz DW Kigali - it occupies a full 12 kHZ,
making listening on the adjacent channels of 6145 and 6155 kHz quite
impossible, even with my top end radio's.

So next time you are plagued by monkey chatter, don't blame your own
radio, as it may be a "dirty" transmitter spewing splatter well
outside it's assigned channel range.

Have fun, good DX and enjoy your radio's.

John Plimmer, Montagu, Western Cape Province, South Africa
South 33 d 47 m 32 s, East 20 d 07 m 32 s
Icom IC-7700, Icom IC-756 PRO III with MW mods
ERGO software
Drake SW8. Sangean 803A
Sony 7600D, GE SRIII, Redsun RP2100
Antenna's RF Systems DX 1 Pro Mk II, Datong AD-270
Kiwa MW Loop.
http://www.dxing.info/about/dxers/plimmer.dx