RF Sampler

[Radio Tech]

Well it is a start. But the data displayed does not really tell you a lot, in theory, I agree with CK you have no trigger, If you really want to get fancy build the circuit I posted above. With it you can look at the rf carrier and demodulated audio imposed on one another. What you are seeing on yours is a modulated carrier less trigger. The scope you have will display X and Y mode so you can see a trapezoid wave form if needed.

 

[LeapFrog]

Well it is a start. But the data displayed does not really tell you a lot, in theory, I agree with CK you have no trigger, If you really want to get fancy build the circuit I posted above. With it you can look at the rf carrier and demodulated audio imposed on one another. What you are seeing on yours is a modulated carrier less trigger. The scope you have will display X and Y mode so you can see a trapezoid wave form if needed.

I just need to salvage or acquire the required diodes for the detector and order another BNC jumper!
Thank You Radio Tech
-Leap

 

[rabbiporkchop]

This seems to be the best homebrew sampler I have seen yet. It doesn't pick up noise like some other homebrew samplers I've seen. -20db to -58db attenuation with the variable air gap.
https://www.briandorey.com/post/variable-rf-signal-sampler

For someone unable to afford the Bird 4273, it looks like a viable option.

 

[Captain Kilowatt]

This seems to be the best homebrew sampler I have seen yet. It doesn't pick up noise like some other homebrew samplers I've seen. -20db to -58db attenuation with the variable air gap.
https://www.briandorey.com/post/variable-rf-signal-sampler

For someone unable to afford the Bird 4273, it looks like a viable option.

Actually that looks like a very good sampler. I can't remember how many I have seen thrown into a plastic hobby box. I like the capacitive coupling as long as it has GOOD insulation from making direct contact with the thru-line section.

 

[Beetle]

Here's another good one to use Every toolbox needs one of these

and another that is in the ARRL Handbook is quite handy as well. It is made from copper pie and a copper Tee and end cap. I can't find a pix online anywhere but I will try and find my old one I have here somewhere. It is great for VHF and UHF pickup but will work on HF as well.The great thing is that it does not upset the SWR on V/Uhf.

Where do you find the copper pie?

 

[nomadradio]

I really prefer an envelope detector.

All you get is a DC voltage from the carrier and the audio envelope riding on it. Just about any 'scope will display this just fine, whatever the rated bandwidth may be.

Best advantage for me is that I can trigger the 'scope on the audio envelope this way. A 100 MHz 'scope displaying your RF signal is probaby quite capable of triggering to the 27 MHz carrier wave. But your audio is what we care about. Persuading a 'scope to give you stable trigger from the audio envelope alone is a bit tricky.

The venerable old Heathkit "cantenna" dummy load has one of these built in, feeding a phono jack. You have to make the RF-bypass ceramic disc cap smaller, and put a 10k resistor across the output to get a good audio waveform.

Gotta build one to go inline with the coax.

Oh, wait a minute... I already did.

Never have plugged it into a 'scope. Oughta do that.

73

 

[Captain Kilowatt]

Where do you find the copper pie?

Really? I mean really Pat? Nine years later and you just caught it? You are slipping my man.

 

[Beetle]

Really? I mean really Pat? Nine years later and you just caught it? You are slipping my man.

I have been busy perfecting my Universal Solvent, and I finally made a batch. Now what can I keep it in?

Actually, I was just skimming through some older threads and "copper pie" jumped off the page and smacked me right across the face. At least that's the way it seemed.

 

[Captain Kilowatt]

I have been busy perfecting my Universal Solvent, and I finally made a batch. Now what can I keep it in?

Actually, I was just skimming through some older threads and "copper pie" jumped off the page and smacked me right across the face. At least that's the way it seemed.

I must have typed that line before I blew the crumbs out of my keyboard.

 

[QRP 725]

Here is how the dummy load sampler turned out BTW.

Here's a homebrew RF sampler that's easy to build. I use this to connect to an Oscilloscope and Frequency counter (T off the BNC plug) It's pretty straight forward to build and the pictures pretty much explain themselves.

Here's the inside...note the resistor and the ferrite core.

What toroid mix? Thanks for posting this design.