The auto charger cable for my Treo does appalling things to the A.M. stations I listen to. Out of nowhere, there will be a very low hum that slowly increases in frequency to a high pitched whine, then slowly declines again to a low hum.
It doesn’t seem to be limited to one station. Oddly enough, I heard it on 1010 the first time. I swapped to 880 which was clear as a bell. Then, the other day I had 880 on at first and the same thing happened. I went to 1010 and THAT was clear.
I do use other devices in other charge ports at the same time, and I’ve never been aware of anything causing audible interference like this.
Could it something faulty in this particular cable? I hate to get a second charge cable just to find out it is inherent in the Treo charge cables.
Try a few snap-on ferrite chokes on the power wire leading to the lighter socket. It sounds like noise from the charger’s switching power supply is leaking back into the electrical system; the chokes should help reduce or eliminate it. The variation in the affected frequency is possibly due to temperature swings.
Interesting- it did go from mildly cool to colder than a witches…well. You get the idea.
A new wrinkle. It happened this morning as I was driving, so I pulled that “offending” adaptor cord. It still happened. Then I pulled the power/attenuator jack for my XM Radio.
It still happened. Not on all A.M. channels, but there it was.
I’d hate to think that I was the one in need of snap-on ferrite chokes. :eek:
Finding the problem in the car can be a cast iron bitch. Anything from a loose antenna connection to ungrounded wheel bearings can cause noises (Yup we had one model car that the rear wheel bearings were not grounded and caused static on the AM stations.)
Does the interference change with road speed or engine speed?
Will it still do it if you stop the car and turn off the engine, but keep the key on the “accessory” position so the radio stays on? That will narrow down considerably the range of possible causes.
Good questions all around. I am at work, I will listen as I get close to home later tonight and if it occurs as I am coming to where I can pull over, I will do so and kill the engine but keep the radio on.