We used them as part of a frequency calibration setup when we had to run tests/repairs on a Nike Herc missile test chassis. Feed a small klystron into a can with a vernier volume adjustment and measure the output. Set the can to the frequency you are looking for and adjust the size of the klystron cavity to match by watching the output of the detector on a meter. None of that digital crap for us - 45 years ago.
You'll find similar in wattmeters and RF voltmeter probes, as well as demodulator probes in a variety of instruments. Many used Geranium diodes with a low forward voltage, and some have tried building some with Schttoky diodes. However, the more accurate used a vacuum tube diode in the probe. HP, Hickok, and Eico used this method. The Struthers wattmeter, AN/URM-120, used a cartridge diode in the element. There wasn't much else besides a feed-through cap and a resistor, if I recall. The four power settings are determined by a cam in the element, which raises the pickup element away from the line section's line between the input and output terminals. It works similar to a variable piston attenuator and is very accurate.
These were used all over the Army satcom terminals I worked on in the 70’s. Just as you described, typically a 30 or 40 dB coupler on the output waveguide given the high power and other coupling values in other parts of the RF chain. Used to monitor output and for fault detection.
These are still used in the linear accelerators I work on, and similar power microwave systems, usually in the AFC circuits, or for monitoring the envelope of RF signals on a scope.
Old radio measurement is always nice to see. Sometimes it seems close to black magic, especially when measuring anything microwave! My first rf measurement device was like that, one made of a diode and a cap when my best-I-can-afford 10MHz (20MHz?) oscilloscope was far from what I needed.
In the 80’s most RADARS still used a crystal diode right after the Tx/RX switch to detect the reflected signal. No fancy receiver, just the diode detector that gets fed into an amplifier and then into the range gates. The dish and waveguides formed the tuned circuit. Those diodes were very sensitive to large RF fields, so you had to take great care that in the case of another co-located RADAR on a close frequency, that the antennas could never point to each other. One transmit pulse-train would blow the detector-diode on the other system if the antennas look at each other…
Very interesting video, great seeing an old crystal detector from well before my time! working with microwave up and down converters for electronic warfare applications we couple the incoming RF to a SDLVA such as the ADI HMC913 die that outputs the video signal proportional to the detected RF signal (0.6-20GHz). Interesting to see the size difference on how big this crystal detector is compared to the .0509”x .0444” die dimensions of the HMC913!
I saw you tapping with that thing in another video. Is that a guitar pick? Somehow it has the right amount of capacitance to use a touchscreen? Pretty cool discovery!
I tore down a Polorad microwave signal generator, a real boat anchor. I still have a crystal detector from it, but I never really understood what it was used for until now.
you still don't quite understand. the output of the detector is just a voltage that is proportional to the amplitude of the GHz signal. it can follow the modulation at audio frequencies but no faster. it is the same as the demodulator in an AM radio.
@IMSAIGuy "Measuring" meant frequency to me, and the example wave shown reinforced my mistake. I get that it's for amplitude measurement. Thanks for the follow-up and reference.
Nice ringtone!!! Wouldn’t it be awesome if you had “Baba O’Reily” as the channels intro tune. If wishing only made it true. Thanks for the video. You have a knack for conveying ,sometimes, dry topics in a a lively and enjoyable way. Keep on keepin on!
I see a generic "avoid static" label with "Max Discharge = " = _blank_ nothing there so your guess would be as good as mine. I do know interpreting this sort of thing literally it then turns into 'antistat religion' complete with antistatic equipment and all that, demonising 'static' and then blaming anything that ever goes wrong as being because hadn't connect the wrist band to ground properly.... @@haroldsmith45302
Strange. My reply disappeared so reposting. Yes generic "avoid static" label but says "Max Discharge = " = _blank_ so your guess would be as good as mine. I do know when interpret this sort of thing literally it then turns into 'antistat religion' complete with the antistatic gear and all that then if anything ever goes wrong blame it on hadn't connect the wrist band to ground properly.. @haroldsmith45302
We used them as part of a frequency calibration setup when we had to run tests/repairs on a Nike Herc missile test chassis. Feed a small klystron into a can with a vernier volume adjustment and measure the output. Set the can to the frequency you are looking for and adjust the size of the klystron cavity to match by watching the output of the detector on a meter. None of that digital crap for us - 45 years ago.
I love the RF stuff, your good at it!
Very impressed that you are using the baba o'riley ring tone! Who's Next was the greatest album of all time...
You'll find similar in wattmeters and RF voltmeter probes, as well as demodulator probes in a variety of instruments. Many used Geranium diodes with a low forward voltage, and some have tried building some with Schttoky diodes. However, the more accurate used a vacuum tube diode in the probe. HP, Hickok, and Eico used this method.
The Struthers wattmeter, AN/URM-120, used a cartridge diode in the element. There wasn't much else besides a feed-through cap and a resistor, if I recall. The four power settings are determined by a cam in the element, which raises the pickup element away from the line section's line between the input and output terminals. It works similar to a variable piston attenuator and is very accurate.
Great choice of ringtone! 😎
These were used all over the Army satcom terminals I worked on in the 70’s. Just as you described, typically a 30 or 40 dB coupler on the output waveguide given the high power and other coupling values in other parts of the RF chain. Used to monitor output and for fault detection.
I used them with the sweeper to tune 70 Mhz IF strips.
There was some small part of me hoping the phone ring was the AM modulation, and that the Rigol was demodulating/playing it. Pity.
I thought the same...was thinking the RIGOL guys were cooler than I thought with that as an easter egg ;-)
Me too.
These are still used in the linear accelerators I work on, and similar power microwave systems, usually in the AFC circuits, or for monitoring the envelope of RF signals on a scope.
Old radio measurement is always nice to see. Sometimes it seems close to black magic, especially when measuring anything microwave! My first rf measurement device was like that, one made of a diode and a cap when my best-I-can-afford 10MHz (20MHz?) oscilloscope was far from what I needed.
Baba O'riely ring-tone? LOL
Got one of these old power heads forming the sensor for a new power meter based on an M5stack (ESP32 based displaymodule) ...all good stuff
I just read the other comments (I usually do before I post, but not this time) and I see your followers are a bunch of us oldtimers😊
13-17 years
0.4%
18-24 years
13.3%
25-34 years
20.6%
35-44 years
17.5%
45-54 years
16.0%
55-64 years
16.3%
65+ years
15.9%
We still use these (diode detectors) for our NMR spectrometers so we don't need to have a GHz scope when troubleshooting amplifiers.
In the 80’s most RADARS still used a crystal diode right after the Tx/RX switch to detect the reflected signal. No fancy receiver, just the diode detector that gets fed into an amplifier and then into the range gates. The dish and waveguides formed the tuned circuit. Those diodes were very sensitive to large RF fields, so you had to take great care that in the case of another co-located RADAR on a close frequency, that the antennas could never point to each other. One transmit pulse-train would blow the detector-diode on the other system if the antennas look at each other…
Used this when doing radar maintenance in the navy.
Very interesting video, great seeing an old crystal detector from well before my time! working with microwave up and down converters for electronic warfare applications we couple the incoming RF to a SDLVA such as the ADI HMC913 die that outputs the video signal proportional to the detected RF signal (0.6-20GHz). Interesting to see the size difference on how big this crystal detector is compared to the .0509”x .0444” die dimensions of the HMC913!
I saw you tapping with that thing in another video. Is that a guitar pick? Somehow it has the right amount of capacitance to use a touchscreen? Pretty cool discovery!
I think those stair steps on the scope are called quantization noise.
I tore down a Polorad microwave signal generator, a real boat anchor. I still have a crystal detector from it, but I never really understood what it was used for until now.
I seem to remember longtime ago something like this used as a hetrodyne detector thingy.
it's only teeeenage waaasteland
he's found crystal island!! oh joy!
solomon island radio station in the past use this kind of detector Sir
OLD TIMERS 😮 Holly crap 🤨 You know how to make a guy feel bad 😢. THAT'S OK I ❤ your videos.😂😂😂 73 Leo
How did this enable the higher frequency measurements compared to other instruments capability?
microwave diode allows rectification into a DC voltage
@IMSAIGuy Thanks. So, a scope would better process a GHz pulsing dc signal than GHz ac signal?
you still don't quite understand. the output of the detector is just a voltage that is proportional to the amplitude of the GHz signal. it can follow the modulation at audio frequencies but no faster. it is the same as the demodulator in an AM radio.
www.electronics-notes.com/articles/radio/modulation/am-diode-detector-demodulator.php
@IMSAIGuy "Measuring" meant frequency to me, and the example wave shown reinforced my mistake. I get that it's for amplitude measurement. Thanks for the follow-up and reference.
Nice ringtone!!! Wouldn’t it be awesome if you had “Baba O’Reily” as the channels intro tune. If wishing only made it true.
Thanks for the video. You have a knack for conveying ,sometimes, dry topics in a a lively and enjoyable way.
Keep on keepin on!
Damn copyright nonsense prevents that, sadly. 'Won't get fooled again', would also be a great choice. The Who were amazing.
Baba O'Riley
for extra points:
who was baba
who was riley
@@IMSAIGuy Wikipedia has the answer - I did not know the story :)
Are some of these crystals degraded by ESD?
Bottom-most label seen at 01:01 seems to suggest that.
I see a generic "avoid static" label with "Max Discharge = " = _blank_ nothing there so your guess would be as good as mine. I do know interpreting this sort of thing literally it then turns into 'antistat religion' complete with antistatic equipment and all that, demonising 'static' and then blaming anything that ever goes wrong as being because hadn't connect the wrist band to ground properly....
@@haroldsmith45302
Strange. My reply disappeared so reposting.
Yes generic "avoid static" label but says "Max Discharge = " = _blank_ so your guess would be as good as mine.
I do know when interpret this sort of thing literally it then turns into 'antistat religion' complete with the antistatic gear and all that then if anything ever goes wrong blame it on hadn't connect the wrist band to ground properly..
@haroldsmith45302
Why is it clipping on the bottom?
it is a diode so has a 'log' response and then when displayed on a linear scale it looks that way
@@IMSAIGuy Thank you for the explanation, VF is a piece of cake for me, I thought it was a notch to the maximum.
Nice day 🙂 Tom