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MAX2630 on HF 1-30MHz?

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neazoi

neazoi

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Hi I connected the max2630 using 100nF input and output caps and 5V prior to an sa612an mixer, to be used as a tiny HF RX.
But the weird thing is that it seems the max2630 has no effect in the signal (listenning to the speaker AF level).

The datasheet does not specify it for such low frequencies but I do not see why it shouldn't operate there.
What am I doing wrong?
 

Input and output coupling caps must be >50nF but it should still work at LF. It isn't designed as a low noise pre-amp and it's voltage gain isn't particularly high but it should show some change. Bear in mind it's an RF amplifier but you are saying it doesn't effect audio levels, they are not the same thing.

Brian.
 

I think he want to say that is using MAX2630 as an RF amplifier in front of a mixer SA612, but the circuit doesn't affect the the demodulated signal (audio).
If MAX2630 is working fine (about 15dB gain), yes, you should hear a bit of difference when listen the audio signal, if MAX2630 is turned ON or OFF.
Check its DC current, which should be about 7 to 15mA for proper gain. If the circuit works at 100MHz should work fine at lower frequencies, as 10MHz or 30MHz.
 

the data sheet says it has gain at 50 mhz, but does not say anything else.
SOME of these types of amps use feedback and active bias circuits that KILL the DC gain....so below 50 MHz, you might be operating in a zone where it no longer is an amplifier.
 

I don't think he needs the gain to start from DC, from the moment the circuit is placed before the mixer.
The S-parameters shows 22dB of gain at 50MHz and I am confident it has some decent gain at few MHz.
 

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