Having recently purchased new hearing aids, I also purchased a, what they call an "EasyTek", it has a "T" coil which loops around my neck. This Easytek communicates with the hearing aids, and has various inputs, one of which is Bluetooth. With the Easytek comes a Bluetooth transmitter which I can use to connect the TV, music etc, via Bluetooth to the Easytek.
One of the devices I wanted to hear was the UHF radio, and it does work, I can hear all incoming transmissions, while the passengers in the car don't hear a thing, good so far, until I start the diesel motor and I am getting the high shrill of the alternator.
The Oricom UHF has an external speaker jack, and I have connected to that, the noise is not coming from the USB power lead, but the input lead from the speaker jack of the UHF to the Easytek blue tooth transmitter, if I pull the plug out of the speaker jack of the UHF, the alternator noise stops.
Any ideas as to how I can stop this noise, or has the project fallen off the rocks?
-- Edited by iana on Thursday 11th of January 2018 11:05:56 PM
I think you have to buy one of their bluetooth transmitters which will plug into the Oricom speaker jack and transmit the UHF audio via bluetooth to your easyTek device which then sends it to you hearing aids.
That's the way I understand it from the owners manual....sounds like a handy device.
Sorry original post edited. I wonder if I should connect an earth wire from the chassis of the UHF to the vehicle, and not rely on the negative supply as the earth?
A number of things that might help and not cost a fortune. Buy a few ferrite tubes from Jay Car (LF1250, LF1256, LF1268, LF1260 gives a range of sizes) or the like and thread the positive and negative supply leads to the UHF radio through a few times to make a loop from the exit around the outside and back through again, the same for the speaker jack lead going to your blue tooth transmitter and see if this improves the sound quality. Another possible improvement is a shielded cable for the speaker jack to the Bluetooth transmitter to reduce this cable's tendency to become an aerial that picks up any stray noise.
T1 Terry
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And just my 2 bobs worth get a .001,.01.1mfd 10mfd 100mfd and parallel them all up and put them from the output terminal to case of the alternator in the hope that you could bypass various frequencies generated by that dirty alternator down to common earth
And just my 2 bobs worth get a .001,.01.1mfd 10mfd 100mfd and parallel them all up and put them from the output terminal to case of the alternator in the hope that you could bypass various frequencies generated by that dirty alternator down to common earth
That's a good suggestion as is Terry's ferrite bead suggestion. Another thing to do is to try and get as many of the car panels as possible electrically bonded to the -ve battery terminal and each other. A google search for "taming alternator whine" may provide you with some more clues.
As a Radio Amateur (HAM) I can tell you that whatever you do, alternator whine is about the most difficult RFI to tame due to the spiky output waveform.
Earthing & adding capacitors can make an enormous difference.
In my Telstra days I had Mt Isa staff chasing a spurious interference on the Burke & Wills to Burketown radio system. It took over twelve months to locate as it was intermittent. We isolated it to a site (Beamsbrook). The fault - the station (rack) earth was not tied to the tower earth - something we all overlooked & assumed that it was done on installation. Someone obviously has another use for that length of cable!!
In the bad old days when transistor car radios were installed, it was standard procedure to add a .01mfd capacitor to the output of the generator/alternator to get rid of the whine.
Hi Terry,
I've always wondered what that "lump" in computer accessory power leads was for - thanks for the info.
Happy hunting,
Warren
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I am reading, and have had a look in the Altronics manual, "Round Cable Suppression Cores" is that what we're talking about? For high frequency ground current suppression in multicare cables. Also I have found what they call a "Hi-Low converter" which the radio speaker output goes into and it is converted into an adjustable low level input for the receiving amp. It also filters noise. Amazon have many of these on their web site, Altronics have one in the catalogue, just can't fid it at the moment.
The whine is high pitched, and the volume and frequency increases with engine speed. I can remember the days of condensers, but I would have thought the world had moved on since then.
Thanks for the effort guys.
The interference ,although alternator sourced, can be radiated from adjacent wiring
A Combination of ferrite & capacitor should help over come the problem
Usually best done as near as possible to the device with, as others have said ,as many loops as possible through the ferrite[you cannot have too many ,then between that ferrule & the device fit a decent sized capacitor between the plus & Neg cables, with another ferrule after that'.
Thanks oldtrack, are you saying that I have to put the suppressor on the power lead, not the speaker lead, as when the speaker lead is disconnected there is no noise.
Just an up-date, as per the advice given, I went to Altronics, with all the gear and showed them the problem, and how a "Round Cable Suppression Core" may solve the problem, they let me take one out of the shop to try in the vehicle, and it got rid of 75% of the wine, they also suggested a "C9556 Buzz/Hum Isolator converter" a double transformer which when fitted it was fitted cleaned up all of the rest of the rogue noise. So a good out come.
