Mismatch&power leakage with port of mixersattenuators solution

[Fovakis]

Hi ! I am making an RF Transmitter and i have a problem with power leakage for LO port to IF port and RF port. I don't know what to do and i am little confused about how can i fix this.


Source(-10 or -20dBm) 10KHz --------->MIxer conv.loss=8db--------->RF port

and

L.O=70MHz and 7dbm

I put an oscilloscope to mixers input IF and i don't see a sin wave from my Source. I is a sine wave with a lot of phase noice and amplitude variations..when i decrease the L.O power the sine becomes better.

I have heard about attenuators but i cannot understand how they will solve the problem. They attenuate maybe the standing waves that maybe create ?Also and my signal right?
I don't understand...

 

[berkeman]

Can you post a schematic and some photos? What bands are you building this transmitter for?

 

[Fovakis]

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[/URL]of course...here...i have some problem with the crystal filter there..but basically this is my transmitter...i think i will need attenuators sure before the mixers...

 

[davenn]

just a little note on circuit symbols...

are they supposed to be band pass filters ??

if so you need to learn to draw them correctly, the centre sine wave shouldn't have a strike through it ;)
as you have shown them they let nothing through low mid or hi

Dave

 

[Fovakis]

Hi yes they are bandpass.look here:https://www.amcrf.com/products.aspx?sc_state=2&sc_id=148679&sc_cat=3768&sc_search=&sc_search_radius=

Can you help with the attenuators please?>Any idea?