[AMRadio] Anti-AM Opinionated Hams


D. Chester k4kyv at charter.net
Thu Nov 22 12:29:28 EST 2007


I have observed that AM operators can be just as culpable as SSB operators 
when it comes to claiming "ownership" of certain frequencies.  I have heard 
SSB QSO's start up somewhere within the Ghetto while there was no-one using 
the frequency, and AM'ers actually break into the QSO and advise the 
offending stations to QSY because they in the "AM Window".  To me,  that's 
no different from the 3892 and 3878 groups or the macaroni net claiming 
ownership of the frequencies they use.  Also, I have heard AM operators 
admit over the air that they knowingly started up only a couple of kc/s away 
from an ongoing "slopbucket" QSO.  When we conduct ourselves over the air in 
that manner, we are doing exactly the same thing that we complain about the 
slopbuckets doing.

But by the same token, I refuse to recognise Dead Air Groups.  If 3892, 
3878, the macaroni, AM Window  or any other "owned" frequency happens to be 
clear, it becomes fair game for anyone to occupy. If I fire up nearby, then 
the frequency is in use - by me!  If you are queued up in front of the 
service window inside the bank, and you step away to take care of other 
personal business, you don't return to your old spot when you finish.  You 
go back to the end of  the line and start waiting for your turn all over 
again.

The best way to handle the  frequency issue is to open your receiver to a 
comfortable selectivity, considering band conditions at the time.  Then try 
to find a spot where you hear minimal QRM with the receiver set at that 
selectivity, and settle in on that frequency.  Preferably, you would have 
some means of adjusting transmitter frequency response so that you could 
adjust your occupied bandwidth to coincide with your receiver selectivity. 
No point in transmitting audio out to 8 kc/s (total bandwidth 16 kc/s), when 
the band is so crowded that no-one is going be listening on a receiver that 
is set for more than 6 kc/s of selectivity.  I have two passive low-pass 
audio filters in my transmitter audio chain.  One gives a gradual cutoff 
above 5 kc/s, so that everything is gone past 7.5 kc/s.  The other has a 
very sharp cutoff at 3400~.  At 3300~ there is less than a dB of 
attenuation, but at 3500~ not enough signal gets through for the modulation 
to be detectable on the scope.  Those filters are surplus items I picked up 
at different times, that had accumulated in my junkbox.  Similar filters can 
be found at hamfests and other sources, or even homebuilt.  There is quite a 
bit of data available on active filters that are easy to build.  Even a good 
graphic equaliser could be made to serve.  When activity on the band is 
light, I usually employ the 5 kc/s filter, but when I have to cut the 
receiver down to 4 or 6 kc/s bandpass to find a clear spot, I try to 
remember to switch in the 3400~ audio filter.  I rarely switch the filter 
unit out altogether, since my transmitter's response is flat well past 11 
kc/s.

Another thing I find irritating, which discourages me from operating in the 
Ghetto, is that AM stations will sometimes fire up within 4 or 5 kc/s of 
each other.  It is physically impossible to operate that close together 
without some sideband overlap.  Better to spread at least 7 kc/s apart 
whenever possible.  When the band is congested, I can usually copy fairly 
comfortably when when another AM station with a clean signal is only 5 kc/s 
away, using the 6 kc mechanical filter, but at only 4 kc/s away, I have to 
use the 4 or even 3.1 filter, and tune slightly to one side.  There is no 
reason to have to do that when there are unused frequencies nearby.

When I start up on a clear frequency, and after my QSO is firmly 
established, a SSB group knowingly starts up only 2 kc/s away and then 
proceeds to gripe about the AM QRM, I am  stubborn enough for that to make 
me feel more determined than ever to stay put.  If they can put up with my 
splatter, I can tolerate theirs.  Besides, the AM signal I am trying to copy 
has two sidebands - sort of a diversity reception situation.  Very rarely 
does intentional SSB QRM make it impossible for me to copy the other 
station, even on my half-century-old receiver. But I make it a  point never 
to mention the QRM over the air and give the offending operators the 
satisfaction of knowing that I am even aware of their existence.

Don k4kyv 



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