45MHz interference
时间：03-23
整理：3721RD
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Hi,
I have an RF that has a discrete LC filter at 135.42MHz and IF is at 15.42MHz. Whenever I switch on a 90MHz to 45MHz T-Flip flop I get a spike in IF at 15MHz even if this is around 15cms away. I have tried shields what else can be done.
BRM
I have an RF that has a discrete LC filter at 135.42MHz and IF is at 15.42MHz. Whenever I switch on a 90MHz to 45MHz T-Flip flop I get a spike in IF at 15MHz even if this is around 15cms away. I have tried shields what else can be done.
BRM
It seems the 3rd harmonic of the 45 MHz will fall within the passband of the RF. 45*3 = 135 MHz.
You have to separate the digital circuits from the RF circuits. Do they reside on the same PCB? If so, it's best to separate the digital and RF circuits into two separately screened metal boxes, using feedthroughs for DC supplies and carefully routed and grounded RF coaxial cables for the RF circuits.