ka9lay
10-05-2001, 12:32 AM
The matching case and knob set for the stereo transmitter FM-10A kit is made of plastic. I have found that the frequency stability improves if you spray the inside of the plastic case with a product from MG chemicals called SUPER SHIELD. This product is a conductive nickel coating that reduces or eliminates EMI / RFI interference.
I was able to mask areas on the outside of the plastic box with kapton tape so as to spray only the inside of the plastic case.
You will have to mask a small circular area underneath the top cover to avoid shorting the whip antenna to the case.
The conductive nickel coating created the same effect as a metal shielding.
When the stereo transmitter is placed within a shielded box, so that it is over a ground plane surface, there is less influence to the circuit from the environmental factors such as capacitance to other nearby objects, and electromagnetic fields.
The combination of spray shielding, and small ferrites clamped over the audio inputs near the phono jacks of the FM-10A completely eliminated audio hum and hiss when using my computer CD player.
[ October 05, 2001: Message edited by: Edward ]
I was able to mask areas on the outside of the plastic box with kapton tape so as to spray only the inside of the plastic case.
You will have to mask a small circular area underneath the top cover to avoid shorting the whip antenna to the case.
The conductive nickel coating created the same effect as a metal shielding.
When the stereo transmitter is placed within a shielded box, so that it is over a ground plane surface, there is less influence to the circuit from the environmental factors such as capacitance to other nearby objects, and electromagnetic fields.
The combination of spray shielding, and small ferrites clamped over the audio inputs near the phono jacks of the FM-10A completely eliminated audio hum and hiss when using my computer CD player.
[ October 05, 2001: Message edited by: Edward ]