[Scan-DC] Mobile Installation Interference

Sat Apr 6 14:08:54 EDT 2013

Hi Dewey (and all),

Thanks for the replies and thoughts and ideas... I just took the BC-396 Uniden portable out and was getting the same interference, independent of the vehicle's power supply.  Good idea on the fob, I'll try that, but I'm beginning to believe that this is data from the Body Control Module that's running all the time - add to that that I just got it with the portable, so I believe it's coming in from over the air, as opposed to through B+.

Also had a private msg from Derek Kelly at MWAA who says that they had big issues with this on Tahoes and Suburbans with Motorola radios; he's going to do a little digging for me.  I want to try to find out if the police / special service vehicles have additional suppression... I have a bunch of literature from the upfitter, don't remember seeing anything in there but am going to have another look.

I'm beginning to wonder if this might not be a significant problem, there are a whole bunch of these vehicles out there in police and fire use, and more coming with the demise of the Crown Vic police car... gonna do some google-ing... I guess I'll have to find out where the BCM lives and wrap it in tinfoil or lead or copper or something.  :(

Did I mention that I do not like this truck?  I also want to change the DRL blubs from clear to amber, you have to tear the whole front of the truck apart to change them... same thing with adding fog lights in the stock position in the fascia... visibility sucks... cruise control, rear wiper, HVAC, lighting, 4WD and "infotainment system" controls are _all_ stupid... baah...

/rant.

Thx again - if I find out anything significant or interesting, will letcha know.

Regards,

Doug

----- Original Message -----
> From: Dewey <dewey3 at gmail.com>
> To: 'Doug Kitchener' <oldsdoug at yahoo.com>
> Cc: Scan-DC at mailman.qth.net
> Sent: Saturday, April 6, 2013 1:34 PM
> Subject: RE: [Scan-DC] Mobile Installation Interference
> 
> Doug, the most interesting part of this is that it is doing it with the
> engine off.  I can't understand how the electronic ignition products are
> interfering with the reception if they are not talking.  If you are doing
> this in the ACC (accessory) position, and have a lighter jack or other
> usable circuit when the power is all the way off, can you try that?  I know
> you mentioned wiring directly to the battery, but using an always live jack
> or circuit might save you the trouble.  The only other thing that I can
> think of is a keyless ignition.  If you have the keyless ignition, you might
> want to try it after leaving the key fob in the house to see if the
> interference may be coming from the fob and vehicle talking to each other.
> 
> Dewey
> 
> -----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 21:13
> 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
> 