Original article from: Rob Dennis 
 Reposted by Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
  THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL
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Author: Rob,VE3SJN
Subj:   DF'ing a Jammer,some Hints,Kinks & Tips
Revised: Dec. 1997
Part 2 of 3
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
 Find yourself a high-ground spot such as a parking garage roof and use the 4
element beam to get a rough direction to head for to start a search.
 Drive about 2 or 3 blocks in the indicated direction from your high spot and
find a parking lot to pull over in.
 Use the magnet mounted 1/4 wave stuck as far back as you can get on the 
runk
lid of a car or roof of a van,and drive in circle in the nearest large 
arking
lot. Have a co-pilot aboard to watch the signal meter in the radio for a peak
as you drive around.
 This peak should come directly in front of the car's hood,and that's where
you should head for.
 Drive about 2 or 3 blocks in the general direction indicated and find 
nother
parking lot to repeat the `doughnut' driving again to get another bearing.
 Repeat as needed until the signal can be heard with the radio squelch set on
fully.
 Un-do the co-ax connector on the radio so that only the center pin makes any
contact with the jack and see what the signal strength is.
 If you can still hear and see the signal you're getting close to the source.
 Now use the PL-259 or BNC connector instead of your normal antenna and see 
f
you can still hear/see the signal. Replace the connector with a paper clip in
the center of the radio's antenna jack and see what the difference is in the
signal.
 If you can still hear it and see a weak signal on the radio's display you're
close enough to get out of the car and look around for antennas/towers etc.
 If no parking lots close by,then look around for something you can use as a
`block' to knock the signal down.
 A `block' can be anything solid from a garbage dumpster to a full-size van 
r
tractor-trailer's trailer,human torso, or driveway beside a two story house.
 As you move behind or around a `block' the signal should drop on one side of
your blocking object only. When this happens the incoming signal should be on
the -OPPOSITE- side of the blocking object as you have just given yourself a
`null' point.
 If you are using a hand-held for close-in work you can use your own body as
the `block' by holding the HT close to your tummy and turning around in a 
ull
circle to find your `null'. The null will be when the jam-signal is blocked 
y
your tummy from the radio's antenna and the singal meter in the radio drops.
 The paper clip can then be used in place of the HT antenna by simply 
ticking
it into the center of the BNC connector on the HT. With the paper clip acting
as the antenna you should be able to walk right up to the signal's source.
 Once you have the source of the signal pegged to a specific address or car
(it may be a parked jammer) get the address or licence plate tag for later.
 Also take note of specific identifying details of the vehicle or property of
the jammer you may want to use later.(see the `What Happens...' section.)
   UNDER -=> NO <=- CIRCUMSTANCES:
  -CONFRONT THE JAMMER FACE-TO-FACE.
  -TRESPASS ONTO THE JAMMER'S PROPERTY.
  -BREAK ANY LAND-SPEED RECORDS DRIVING AROUND
 Since he/she/it is the one breaking a law why should you?
 A face-to-face may turn ugly if the jammer decides to make it so,and since
you may not know who or what you are dealing with,it makes sense to play it
safe for all the hunters involved.
 Give all the necessary info to the proper authorities and let them deal with
it,as they have the authority to issue search warrants,fines or seize the
offending person's gear.
 Lodge a formal,written complaint with the local FCC or DOC/IOC office signed
by all witness or hunters involved in tracking the jammer.
 If a repeater trustee/owner is involved they should file their own formal
written complaint against the jammer as well.
 Be prepared to go to court IF needed as witnesses.
-
--------------------------
 What Happens if the local FCC or DOC/IOC is taking a long time,3-4 months or
more,to "officialy" do anything to stop the jammer's transmissions ?
 If after all your efforts the jammer still persists in their habits then you
may wish to give a few `subtle' hints as to their identity over the air.
 By `subtle' I mean things like:
 -comment on how ugly a shade of color his garage door is.
 -how badly his garbage cans need to be replaced.
 -how messy his co-ax runs are from the tower to the basement/second floor
window is,and how your 2 yr. old can do better.
 -comment on how the kids shouldn't leave bicycles in the driveway.
  (assuming he/she/it has kids that is)
 -make a comment regarding their cat/dog and how ugly it is.
 -comment on the ugly paint job on the car they drive,and how you would never
be caught dead in such a death-trap. (don't mention the color though)
 -if you know the person's former military rank you can use that to poke fun
at them as well. ("How long did you stay on KP the first time Captain?")
 NEVER give a full-blown ID over the air,just a few hints to let them know
that they have been caught will do.
 As the jammer has had their fun messing with other people's minds a little
directed their way will surely goad them into further action on the repeater
thus strengthening any possible case being made against them.
 It may also give them a case of the shakes that they have been CAUGHT.
 Just remember that the whole time this is going on to have two of the 
unters
parked close enough to the jammer's location to CONFIRM it is them doing it
and not a copycat jammer.
 If it's a copycat,they have just made themselves a target for hunting later!
 Sooner or later if there are enough lodged complaints about the jammer there
will be an action taken against them by the FCC or DOC/IOC.
---------------------
Remember:
- Most jammers require an audience to satisfy their egos,give it an audience
for bait then go tracking.
- The average jammer is scared witless about being caught or identified by 
ny
one who may know them. (public shame when their friends find out)
- If caught most vehemently DENY doing it even when caught by 3 or more of 
he
hunters right to their front doors.
- Most if not all jammers have an ego so big they may be dumb enough to do it
from their own home and think they can get away with it. (BELIEVE IT !)
- Listen to the characteristics of the jammer's signal and if you can make an
audio tape of the signal to listen to again later.
  (you may be able to pick up background noises or microphone characteristics
from your tape-recording that you may have heard before or recognize.)
- KEEP A RECORD of the jammer's habits/time/repeaters or people he/she/it is
in a habit of attacking to get an idea of what their pattern of jamming is.
 (Most jammers DO after awhile get into a habit of doing jamming the same way
every time,which gives you an advantage on being able to predict roughly when
they will be likely to be `out and about' for hunting.)
- A BIG thing to remember is if you intend to start a local DF-ing group is 
o
keep it small and above all.....KEEP QUIET ABOUT IT !  (yes,QUIET!!!!!!!!)
  Something said at the wrong time or place can ruin any efforts to nail a
jammer if they know you exist and are out to get them.
  Any info gathered is to be considered RESTRICTED to only those members out
doing the actual hunting and to NOT BE REPEATED to anyone outside the group.
 Just a few tips to catch 'em and NAIL 'em.
 Hope it helps out,it has worked here to catch and ID at least one jammer.
 For those more interested in it there is a book on transmitter hunting that
is published by the ARRL and they have several methods and articles/projects
to help track and find hidden T's or jammers.
 A properly built Doppler system may get you to the jammer faster than most 2
meter beam multi-element arrays,but it's even better if you have a few 
earing
headings from base stations to narrow a search area down a bit more.
 (saves you wasting your gas !)
--- GoldED 2.42.G1219
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