Low pass filter for intermodulation setup measurements

[Leiser]

Hi all,

I have to do some second order intermodulation measurements for an AM buffer. That´s it, the block just after the antenna and before the receiver.

I need a band pass filter or a low pass filter to make sure that when I combine the two generators I do not introduce any intermodulation.

The two tones are 800 and 900KHz respectively. I tried to design myself the low pass filters but with no luck. I also tried to find SMA filters in minicircuits but the do not cancel the second harmonic, as the minimun starts at 1.9MHz.

Does anyone know any company where I can buy the appropiate filters, o any other suggestions?

Thanks in advance!

 

[biff44]

I do not know what good a lpf would do you. You need isolation from one source to the other. Really narrow 800 and 900 KHz center frequency bandpass filters would work. A 15 dB pad on each source would work too, although you might have to boost the source's powers first.

 

[biff44]

I guess I am assuming a third order intermod test from the 2 tones when I say the above.