HF Noise reduction speaker

Submitted: Wednesday, Mar 26, 2008 at 19:26
ThreadID: 55947 Views:3861 Replies:5 FollowUps:9
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Hi All
First let me state that my electronic knowledge is very limited anyway here goes, I have been having trouble with my new Turbo diesel interfering with the HF radio I have reduced the noise considerably by fitting noise supressors to the electronic fuel pump wiring and I have been advised to buy a ADSP2 Noise cancellation ext speaker to replace existing codan speaker. Has anyone had any experience with these speakers and where do you get them I have tried Dick Smith, Jaycar, with no luck any advise would be appreciated
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Reply By: Member - Phil G (SA) - Wednesday, Mar 26, 2008 at 19:46

Wednesday, Mar 26, 2008 at 19:46
Gday Barry,
I've had the same noise problem, and have been using an ADSP2 noise reducing speaker for about 18months (my HF is a Barret 950). It has 2 levels for the noise reduction. First level works pretty well, second level distorts a bit to much. It also has different levels for filtering, but I don't find these useful.

The first level is good enough for me to now listen in to VKS on the move. But it works really well when in camp, and the engine is not running.

They don't come cheap. I bought mine from Electric Bug in adelaide, but I know from a friend that they have no more in stock at present. My friend has just ordered one from USA.

Here is the manual.

And here is the link to the SGC shop.

If you google HF ADSP speaker, you will come up with other sites and reviews.


AnswerID: 294869

Follow Up By: Member - Phil G (SA) - Wednesday, Mar 26, 2008 at 20:05

Wednesday, Mar 26, 2008 at 20:05
Just to add, it doesn't have an on/off switch. I added one. But Electric Bug said that you could take power from the COM cable that goes to the head unit, so it would automatically turn on and off with the radio.
FollowupID: 560777

Follow Up By: Barry 2 - Wednesday, Mar 26, 2008 at 20:33

Wednesday, Mar 26, 2008 at 20:33
Hi Phil
Thanks for the info I will follow it up, I have a 79 series as well didn't have any issues with the HF in my old 80 series stnd diesel.
Safe Travels
FollowupID: 560790

Follow Up By: Member - Phil G (SA) - Wednesday, Mar 26, 2008 at 21:19

Wednesday, Mar 26, 2008 at 21:19
Yep, same set in a Prado TD was fine too.
I also put some extra earth leads on the exhaust and fuel tank covers - didn't make any difference. There's been a lot of smart HF people who have been unable to significantly reduce the noise from Toyota's 1HD-FTE. The ADSP speaker certainly helps.
FollowupID: 560802

Reply By: obee - Wednesday, Mar 26, 2008 at 19:51

Wednesday, Mar 26, 2008 at 19:51
I never heard of noise reduction speakers but removing the noise at the source by relocating the antenna is the best advice I can give. That and making sure the radio and antenna is well earthed.

Shielding the fuel pump wiring with aluminium tape might help if that is where the problem is coming from. Even a layer of foil might do it. It sounds like the wiring is acting as an antenna sending out a broad spectrum of noise like the high tension wires outside my house when the insulators are dusty and damp.

I once had a two wheel drive hilux with an amateur antenna on the front same problem but probably from the alternator. I put the antenna on the rear corner and no more noise. This is probably why you see so many antennas on the back.

Sorry but that's all I can give.

AnswerID: 294871

Follow Up By: Barry 2 - Wednesday, Mar 26, 2008 at 20:35

Wednesday, Mar 26, 2008 at 20:35
Owen, thanks for the input all food for thought
Safe Travels
FollowupID: 560791

Reply By: Mike Harding - Wednesday, Mar 26, 2008 at 20:04

Wednesday, Mar 26, 2008 at 20:04
If the front end (the antenna) is receiving vehicle produced RF noise then nothing you can do in regard to filtering the audio will improve matters. There is a parameter called “signal to noise ratio” which determines how clear the received signal will be and if the noise is too high then the signal will be unclear. I have that problem on the 3.5MHz Amateur Radio frequency around my house because of RF noise caused by the switch mode power supplies in DVD players etc.

However if the problems you are experiencing are caused by vehicle electrical noise getting in to the radio system via the power supply then an audio filter may well improve matters. However; if you can suppress the noise at source that will be a technically better and certainly cheaper option.

Keep in mind single sideband HF is not an easy communications frequency to get working with good audio in a moving vehicle – I decided it was not worth the trouble. How often do you _really_ need to use it when on the move?

Mike Harding
AnswerID: 294878

Follow Up By: Barry 2 - Wednesday, Mar 26, 2008 at 20:43

Wednesday, Mar 26, 2008 at 20:43
Mike, Thanks for the reply, in my old 80 series the Hf worked a treat enjoyed listening to the radio skeds while driving, the first trip with the new Turbo Diesel was hopeless couldn't listen to the Hf while engine running since I have fitted the ferrite suppressors you can listen to the hf while driving with slight interferance thought the speaker might help just a bit more ?? I will take your comments on board and try some other measures first especially as phil said not cheap $$$
Safe Travels
FollowupID: 560795

Follow Up By: Mike Harding - Wednesday, Mar 26, 2008 at 20:52

Wednesday, Mar 26, 2008 at 20:52
The newer "common rail" diesel vehicles do seem to be problem in that they produce a lot of RF noise in the HF band - the manufacturers should be be required to reduce or prevent this - the rest of us who design electronic equipment are certainly required to do so - perhaps a "C Tick" for cars would be useful?

Mike Harding
FollowupID: 560796

Follow Up By: Robin Miller - Thursday, Mar 27, 2008 at 08:00

Thursday, Mar 27, 2008 at 08:00
Hi Mike

The automotive manufacturers are required to do an equivalent to "C tick" ( I first did one in seventies, when designing Astor diamond dot radios - wasn't called that then though) , but level of noise allowed was around 50uv equivalent at the aerial , compared to the microvolt or so we would like.

Except where there has been an actual fault I have also found it very hard to eliminate noise completely, and as you say not worth the effort sometimes.
I got mad at one car and did it , and this meant essentially putting a shield around everything and earthing it at the soucre.
Robin Miller

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Reply By: Member - Roachie (SA) - Wednesday, Mar 26, 2008 at 21:01

Wednesday, Mar 26, 2008 at 21:01
I have one of these:


(the bhi NES 10-2).

It works reasonably well and has a earphone jack, so you can also plug in some headphones if your SWMBO doesn't like you listening to the HF.

AnswerID: 294905

Follow Up By: Barry 2 - Wednesday, Mar 26, 2008 at 23:12

Wednesday, Mar 26, 2008 at 23:12
Thanks Roachie I will follow it up
Safe Travels
FollowupID: 560850

Reply By: Member - Mark E (VIC) - Thursday, Mar 27, 2008 at 09:16

Thursday, Mar 27, 2008 at 09:16

To those of us that have an ongoing interest in HF, noise reduction in mobile installations is important and it seems that the newer technology vehicles with the multitude of computeries controls couse havoc with many of the HF bands.

Two vehicles spring to mind that are very 'noisy': Yours...the Turbo Diesel Landcruiser and the other the Landrover Discovery TD5.

The problems can largely be overcome, but it depends on how much you want to pay someone else to do it or how much time you have to fiddle around with your installation.

I used to have a Discovery (although the earlier model) and had moderate RFI, which I overcame to some extent with earthing, filtering and ferrites, but it was only a slight improvement. Since then I now have the 'older technology' non-turbo diesel Landcruiser and have absolutely NO noise on the HF bands except for one frequency that seems to pick up the speedo sensor and as yet haven't had the time to worry about it.

Have a look at this link:

Great mobile installation website

as I think it is the most comprehensive I've found in describing the various types of interference you will find in mobile installations and how to supress them.

Also have a look through the archives of the following yahoo group as there are many members her experiencing similar problems with modern cars. In fact one of the examples in the first link is a member of this group and has done a great job supressing noise in his Discovery, all be it with some serious work.

I have one of those speakers you mention and whilst I think they're OK (take some getting used to the different 'sound'), I'm not sure they're worth the $$. From memory mine was near $200? I think you will be disappointed in their effect at reducing the problem you have. As others' here mention, it is better to attack the source(es?) of the noise you have rather than trying to mask it.

Hope this helps.


AnswerID: 294961

Follow Up By: Member - Mark E (VIC) - Thursday, Mar 27, 2008 at 09:17

Thursday, Mar 27, 2008 at 09:17
Woops....forgot top include the link. Here it is:

Codan Yahoo Group

Have fun.


FollowupID: 560889

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