A reason why DVD players don't have RF modulators

[wa2ise]

Originally Posted by kf4rca

...must some shielding issues in your conversion.

Rerouting the wires feeding the modulator's power helped a lot. Still not prefect, still some sparkles left to reduce.

Sparklies increased when I put the metal top cover on... I eventually found that it was a piece of metal mounting bracket not grounded except thru the cover. Seems to be picking up noise off the front control board. Ran ground wires to ground it to the chassis, helped some more. Changed the shielded wire I used to coax, to send the video and the audio to the modulator, helped a little. More power supply decoupling helped a lot. Used a bigger value coil right at the modulator's power input.

Signal to noise is almost acceptable now...

Got it better, I gave the modulator its own 7805 regulator (fed by 12V), mounted right at the modulator. no sparklies now. It's now decent.