[Scan-DC] Mobile Installation Interference

[Bob Crain]

You might want try a bonding jumper between the scanner chassis and a nearby
vehicle  ground ( a seat mounting bolt might be easy).

Bob



-----Original Message-----
From: scan-dc-bounces at mailman.qth.net
[mailto:scan-dc-bounces at mailman.qth.net] On Behalf Of Doug Kitchener
Sent: Friday, April 05, 2013 9:13 PM
To: Scan- DC
Subject: [Scan-DC] Mobile Installation Interference

Need some help, list - I have a 2012 Tahoe; put my Radio Shack PRO-197 in it
and I got occasional bursts of interference when using the radio.  Fiddled
around with it and discovered that this is occurring even when the vehicle's
engine is _off_.  I don't have this problem with the same radio when using
it in other vehicles  (e.g. 2001 Impala).  Even at that, I wondered if it
might have something to do with the technology of the radio itself, so today
I tried the Uniden BC-796 - same problem.  Again, this is occurring with the
engine not running, is in the form of a popping noise or a fluttering
noise.  I noticed it today on a vhf frequency with the Uniden... not sure
whether it's doing it with 800 MHz digital systems or what (still gathering
data); but the fact that the Uniden was getting it as well as the Radio
Shack was a bit of a surprise.

All I can figure is that the "BCM" (Body Control Module) may be the culprit,
as I'm getting this even with the engine off, even though it sounds like
"ignition" noise.


First question:  First, does anyone here happen to be familiar with mobile
installations of professional two-way equipment?  A lot of jurisdictions
around here are using Tahoes for police and fire work... wondering if anyone
has heard anything about this or run into this problem.  Of course there are
Tahoes and Suburbans that are marketed for "special use" or police use, not
sure if they have electrical system mods other than HD charging systems, but
I'm looking into that.  Mine is a "civilian" vehicle, the dealer wouldn't
sell me a 5W4 (a bit to my surprise).

Second question:  Besides connecting the +12V to the radio directly to the
vehicle battery and shielding it, and grounding the radio, can anyone think
of anything else I might do?

The antenna setup I'm using is a bit of a jury-rig... it's a suction-cup
"windshield mount" thing that came with a BC-350 that I have.  The radio is
mounted on a carpet-covered piece of plywood between the front seats, and
the antenna is stapled to the underside of the  plywood (yeah, I know).

Things I'm going to try:

Using a back-of-set antenna just to see if that makes any difference;
Running a +12V lead directly from the vehicle battery to the radio (first
unshielded as I don't think I have any shielded wire around here); Rigging
up some sort of temporary 12V supply, independent of the vehicle's power, to
see if any effect; Trying one of the portable scanners to see how they
behave.

Anybody have any thoughts, ideas, suggestions, questions?  Thanks!

Comment:  I also have a 2001 Tahoe that I've been happy with; the new one
was a planned replacement for the '01.  I saved for three years to
special-order the new one and so far, it's been a significant
disappointment.  This radio business is just a small part of that and the
old one is a much better vehicle in almost all aspects.    If anyone is
considering purchasing a new Tahoe / Suburban / Yukon one and wants to know
the whole story, let me know off-list.  If I had it to do over, I almost
certainly would do the same thing, but note that I'm in the car hobby and
can be very blind about them because of that.  I would probably not
recommend the purchase of a Tahoe or Suburban to someone who isn't wedded to
General Motors products.

Regards,

Doug
______________________________________________________________
Scan-DC mailing list
Home: http://mailman.qth.net/mailman/listinfo/scan-dc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Scan-DC at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html