FM Radio Question

[bmcgeeny]

I have radio clipping that shows up when certain combinations of channels light. I thought I had it solved during testing. I moved the ant wire as far away from the cat five cables as could be, moved the transmitter as far as I could.

But in a test run of the show, it shows up again. Some sequences not so bad, some so much it ruins the music.

I am using the same power supply for the Grinches and some ULN chips, but it's to late to change that. Next I thought I'd try some ferrite magnets. So where should I put them? Since the ant goes outside as coax, that doesn't make any diff does it. So in the input line computer to transmitter? In the power supply line? I got 1/2 dozen of these things. Where will they work the best?

[Virtus]

Try moving the FM transmitter to a different A/C circuit.

[bmcgeeny]

Try moving the FM transmitter to a different A/C circuit.

Problem with that is I am using the same power supply as for the Grinches and some ULN chips driving some relays. I may end up doing just that. My next step is to pull one of the old PC power supplies down and move the transmitter, ant and everything to a differnt location.

I did try 5 ferrites on various cords and it is better.

[Blackbeard]

My house is split electrically almost symmetrically down the middle. Anytime I get problems, I can usually move a circuit to the other side of the house to make things work. My main problem was the X10 devices not working, so i needed to make sure the circuits were on the same side of my mains coming into the house. I'm guessing it's the way the wiring came out of my main breaker box. It's worth a try for you to move one or the other to an outlet far away from the other you're using if you haven't yet.

[sjwilson122]

Two things come to mind and they both lead back to the power supply. what kind of supply and what is its mA or amp rating. You say "grinches" as in multiple. Each grinch running a full load of ssr boards can pull between something like 700-1000mA. If you are running several grinches I would estimate your power supply requirements at 1 amp per grinch plus the current draw of your ULN chips. Also if I am reading this right the transmitter is also running on this supply. The power supply needs to be a pretty healthy one for all this. The sequences that are causing the problem, are they intense sequences with lots of channels on at the same time? If it is it sounds like the power supply is maxed out and you are getting a big voltage drop.

Second thing, have you tried turning down the audio input level to the transmitter when it starts distorting? It takes less power to transmit less volume It may help some but the current draw from the transmitters most of us use here is very low (40-100mA).

I would try the computer power supply with a decent 5 volt, amp rating and see if that cleared it up.