[OZAPRS] Bad HF noises in Landcruiser ??

Ray Wells vk2tv at exemail.com.au
Mon Jul 12 08:51:19 EST 2010


Geoff,

Given the stable, "spot frequency" characteristic of your problem I 
wouldn't even be thinking oil pressure sender or alternator, which both 
produce noise output that varies with engine speed.

I'd be probing around for the source of the signal and I'd start around 
the engine management computer, in whatever form that takes in a modern 
diesel engine. Is there a crystal controlled clock in the vehicle?

Just make up a coaxial cable to go from the rig, with a DC blocking cap 
on the remote end. Start touching things. Even proximity to the source 
should result in a stronger signal. Arm yourself with some "clamp-on" 
ferrite filters to try to eliminate the problem.

Don't overlook body to chasis bonding, which helps to prevent radiation 
of unwanted noise sources. The noise is being received by the antenna so 
it must have a radiation source. I presume the noise goes away with the 
antenna removed, thereby proving it's being radiated rather than 
conducted along power leads, etc.

Bonding won't be effective in every case but really should be the first 
step in trying to eliminate noises.

Ray vk2tv

On 11/07/10 14:40, Geoff wrote:
>
> There's no variation with engine revs, (not like an altenator whine) 
> -- there is a very low level (barely audible) ticking that does seem 
> to speed up slightly with the rpm.  This one's not a common-rail 
> engine...  on reading about common-rail issues the problem there is a 
> high noise level across the board.. in my situation I have no noise at 
> all -- beautiful conditions everywhere except on these annoying 
> spot-frequencies
>
> The Oil sender issue looks interesting -- I'll take a look where that 
> cabling goes and see about shielding it...  see what that does (saw 
> another post there about replacing the sender cable with a coax and 
> earthing the shield).
>
> Regards,
>
> Geoff
>
> *From:* ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] 
> *On Behalf Of *Michael Wain
> *Sent:* Sunday, 11 July 2010 1:57 PM
> *To:* Australian APRS Users
> *Subject:* Re: [OZAPRS] Bad HF noises in Landcruiser ??
>
> is it rev related e.g. alternator revving up and down or is it a 
> constant freq ?
>
> could be cpu, could be fuel pump, could be fuel injectors, could be 
> oil sender. doing a quick Google pulled these WebPages , have a look.
>
> http://www.amalgamate2000.com/radio-hobbies/radio/common_rail_diesel__interference.htm
>
> from chipboy on the overlander 4wd forum, 
> http://forums.overlander.com.au/viewtopic.php?t=41098&start=0&postdays=0&postorder=asc&highlight=&sid=e8ebef4009204a73da498a5f2a4f4802 
> <http://forums.overlander.com.au/viewtopic.php?t=41098&start=0&postdays=0&postorder=asc&highlight=&sid=e8ebef4009204a73da498a5f2a4f4802> 
>
>
> ___________________________________________________________________________________________________________________________________________________________________________
>
> Rerun the oil sender wire using some thin coax and use the centre wire 
> for the sender, earth the outer at both ends and hey presto no noise.
> Might try some suppressors on it too. Just an idea!
>
>
> Matt
>
> *geexel wrote:*
>
> This is a fact.
>
> It is caused by the oil pressure sender to the guage in the instrument 
> cluster on the dash.
> The remedy is to run the wire through a switch on the dash and when 
> you are on the trot and want to use the HF, break the circuit through 
> the switch on the dash, ensuring that you turn it back on especially 
> during those times when the engine is working hard in rough country.
>
> ____________________________________________________________________________________________________________________________________________________________________________
>
> Yours sincerely
>
>
>
> Michael Wain - VK3HAU
>
>
> EGARC Inc. Publicity Officer.
>
> Ph : 613 - 51411650
> Email - vk3hau at vk3egc.org
> Web - http://www.vk3egc.org <http://www.vk3egc.org/>
>
> <>
>
>     ----- Original Message -----
>
>     *From:* Geoff <mailto:geoff at gatwards.org>
>
>     *To:* 'Australian APRS Users' <mailto:ozaprs at aprs.net.au>
>
>     *Sent:* Sunday, July 11, 2010 12:19 PM
>
>     *Subject:* [OZAPRS] Bad HF noises in Landcruiser ??
>
>     Guys,
>
>     A little OT, but perhaps you know the answer J
>
>     Got my HF setup in the vehicle installed and operational during
>     the week -- IC706 (Original Mk1) in a 100 Series Diesel
>     Landcruiser (No Turbo).
>
>     All working great, tunes up on all bands 80m through to 10m with
>     zero noise......   EXCEPT.....
>
>     When the engine is running I get an awful 1-2kHz squeal in a few
>     spots on 40m (thankfully most of the 7xx0 and 7xx5 freqs are free
>     from this problem and quite usable).  The problem is also there on
>     30m and 20m, the noise takes out 10.147 and 14.116 -- two freqs
>     I'd like to be able to access -- but by far the worst is on 40m.
>
>     I can probably live with it on 30 and 20m (call into the travelers
>     net whilst pulled over for a break, and APRS can get away with
>     degraded Rx), but it's really annoying when tuning around on 40m
>     whilst mobile.
>
>     Anyone with a Diesel Landcruiser 100 had/solved this issue ??
>
>     Cheers,
>
>     Geoff   VK2XJG
>
>     ------------------------------------------------------------------------
>
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>
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