HF Noise reduction speaker

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.

Cheers
phil

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.

Owen

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

I have one of these:

http://www.andrewscom.com.au/site-content-section-01-speakers.htm

(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.

Roachie

Barry,

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.

Cheers,

Mark