How to Reduce Noise When Measuring 20MHz Frequency Using Relay

[rtsrhtsh]

Hello everyone,
I'm currently making a test machine for testing (voltage, frequency) PCBs. There are 5 test points on PCB where I need to measure frequency 20MHz. So, I'm using relay to switch around test point and connect to the probe of my oscilloscope (Keysight DSOX1202a). I've found out that relay causes a lot of noise and I'm wondering if I could get help on how to reduce noise and measure 20MHz with stability.
I've tried using SSR type relay, but noise still occurs.

Do you guys know any other relay types that are stable for measuring 20MHz or something else that I could use instead of relay?

Thanks in advance..

 

[danadak]

Are you taking snapshot after relay activated ? Is it broadband noise, can you show noise on source side
of relay and output side to compare ?

 

[poormystic]

Hi rtsrhtsh
A SSR is a solid state relay, so the signal you want to measure is getting noised up by the active electronics in the switch.
I recommend coaxial relays, which are electromechanical switches with very low noise and are usually specified with some frequency dependent insertion loss. Such relays can be controlled by transistors, and might help route the signal from your bed of nails to your test equipment.

 

[Delta Prime]

I'm currently making a test machine for testing (voltage, frequency) PCBs. There are 5 test points on PCB where I need to measure frequency 20MHz. So, I'm using relay to switch around test point and connect to the probe of my oscilloscope (Keysight DSOX1202a

If you’re making a test machine for testing, what are you testing?
You gave us frequency and that’s it!
What is the voltage amplitude what type of waveform at 20 MHz? what type of probes are you using?. have you read the instruction manual?

 

[Harald Kapp]

Most certainly the noise does not come from the relay per se but from the wiring. You need to use shielded wire and a solid ground connection.

 

[danadak]

Post well focused pics of your test setup and a scope shot of noise.

 

[poormystic]

Most certainly the noise does not come from the relay per se but from the wiring. You need to use shielded wire and a solid ground connection.

This is the man to listen to.

 

[ariajames_121]

Hello everyone,
I'm currently making a test machine for testing (voltage, frequency) PCBs. There are 5 test points on PCB where I need to measure frequency 20MHz. So, I'm using relay to switch around test point and connect to the probe of my oscilloscope (Keysight DSOX1202a). I've found out that relay causes a lot of noise and I'm wondering if I could get help on how to reduce noise and measure 20MHz with stability.
I've tried using SSR type relay, but noise still occurs.

Do you guys know any other relay types that are stable for measuring 20MHz or something else that I could use instead of relay?

Thanks in advance..

You might want to try using high-speed analog multiplexers (like the 74HC4067) instead of relays. They’re better for handling higher frequencies with less noise. Also, make sure to shield your circuit and improve grounding to reduce noise. Hope that helps!