Your simple RF Sampler circuit is an unsung hero for anyone who wants to monitor AM and SSB signals!

Hi Alan - - I did something similar without the risk of damage due to switch in wrong position. I ran some rg178 thin coax through gap in my tuner housing to about 20 turns wire wrap wire on a wooden Q tip dowel for a pick up. Works great. -Art, NF1A

An easier way is to just wrap a few turns of wire around the coax and connect to scope. More turns is more signal.

A reason to take my scope out of the shed and give my shack that high tech cool factor!

Very helpful, I have an older 10 Mhz scope and because it was that, I didn't really consider it for HF since I didn't think it would work on the upper bands very well but after watching your other videos showing how they still do work much above the rated freq, just with a lower amplitude response and guess as long as I could see what the signal looked like, that is what I am concerned about, so might play around with that sometime, thanks, all your videos are very informative.

I've done the same thing w/o a tuner. A loop of wire a few feet in diameter works well. Mine consists of several test clips connected together and draped over the curtain rod. I also have several turns of wire wound around the coaxial feedline that does the same thing. Also, I have my Tektronix 2236 (100 MHz) set up with "Normal" triggering and the trigger level set /just/ above zero. Until the 'scope sees some signal, there is no display. That saves the phosphor coating inside the front of the CRT, and extends the CRT's cathode life.

You could put a preamp on the input of the scope too... with a little whip antenna. That's a common feature on communications service monitors.

I tried it with my old Tech 2225 and it worked fine...Thanks !

Excellent, i bought an old scope a few months ago with the intention of learning how to use one, but when i realised i couldn't monitor my own signals with it, i kinda left it on a shelf. But now you've solved my problem for me, this is my project for tomorrow. Love your video's and as you can probably see, i've subscribed to your channel. 73 Jeff M1BCM

I am just using a T adapter to route the signal by the scope. Only doing this for my low power DIY projects as high power could be too high voltage. I checked the datasheet for my Siglent and it can do 10 V per divison at 1:1 (= 80V) and survive up to 400 V peak. Could also unplug the T and use a 10:1 probe for an ugly solution that would handle a lot of power (> 1 kW) but still show the signal sampled directly and thus the correct voltages.

I have an older micronata power/ modulation/ swr meter that has a 1/8"monitor jack I just use a little pig tail and clip my probe to that.

hehe..maybe, but I fried a nice freq. counter doing this (yes, I did it, accidentally set the switch to that port and pumped 25 watts into it)

This is a very handy way to sample, works fine for me. I have various "proper" samplers but they are often hiding. It is tempting to incorporate a dedicated sampling port on my atu.

You can also take a cable out of your scope, and curl it around the antenna-coax. (10-20times perhaps?) That will be enough. No risk of ever transmitting into the scope. I use an old audio-cable i had flying about, but there is certainly better options. You could take a peace of coax, and curl the center wire around the antenna-coax - but the trip from there to the scope remains shielded (shield to ground - center wire to scope channel X)

Thanks, tried this with the SM 220 and worked fine. NL7IB

I just wrap a couple of turns of insulated wire around the antenna coax. One side goes to earth ground. The other side of the coil goes to the scope. Ezzy Pezzy. WA6PBJ

This will also work on a antenna switch.

I never would have thought about doing that....... A stellar idea! RW

I am using a circulator that I removed the shunt. Then you have turned the circulator for UHF into a an RF sampler for the HF bands.

Hello excuse my ignorance but on the modulation do you just use mic gain to adjust? And what does the form look like when properly adjusted? I dont think o have flat topping and im very close to calibrated line on scope

Any reason not to open up the tuner and drill a new hole to mount the connector, then putting a wire inside the case attached to the connector? Essentially a short antenna inside the tuner to eliminate the possibility of ever transmitting into the scope.

Where some confusion comes in is that you can transmit into some of the later service monitors. People see that and than think you can do that with these o'scopes. Personally I avoid doing any of that despite what IFR claims you can do.

Great video , this unused port that is being used to sniff the RF , would this still work for a 15-20w cb radio ssb signal or would the outputting power be too low ? Cheers Alan. 😊

Bit safer... if do not have a purpose made sampler (I have made and used one the simple resistance samplers you show in the video) why not just wrap one end of the scope input feed about the TX RF cable? Take a simple BNC (RG174 or RG58 (thinner so flexible) patch lead, one end you connect to the oscilloscope channel the other strip back the braid for 4" or so and just wrap the centre about the coax, you should see a signal on the scope when you TX. This way you will not TX into your scope and you will still be sampling some of the RF going to the dummy load or antenna. We have all seen or used a clip on ferrite core over a feed line, you have asome wire wrapped about the ferrite and to a uA meter this indicates RF going through a feedline... this is exactly the same principal. Despte the warning I can still see someone if careless might put 5w or even 500w into their scope :-) 72 Dom M1KTA

This video along with many of the others has taught me a great deal about ham radios. I would like to connect an inexpensive scope to my shack but would like to use it to tune up my AL811H much like in another video using a Kenwood sm220. Would that be possible? Thanks again for your time and expertise putting out these great videos. 73 - W0KRD

Thanks for this video Alan, Finding 1n34a genuine diodes is a challenge though. Could you recommend any alternatives that are more widely available please ? Great videos for the radio enthusiast, Congrats.

How about just adding a BNC connector with just a short stub connected to nothing.

Thanks! Very much appreciated!

I have that same scope! I have a Tek with a huge screen and want to make it into a station monitor. One channel is dead, but I have good horiz & vert on the other. I paid $30 + $20 for shipping and got $200 in probes so, the scope is a freebie.

what a great way to monitor your signal. Most ham operators already have antenna tuners. What type of scope would you need. Would a 5MHZ scope be adequate or would you need something better ?

Can you please point me to where the video is to make the RF sampler? Thanks!

Tape a Straight gimmick wire on the coax?

I think I would just mount a bnc on the back of the tuner and tie an unterminated sampling wire inside near the RF lines. Yeah, I know, the point was to make it simple. Well, this is so simple someone (you or someone else) is guaranteed to blow that scope eventually.

Hey brother - I need help, 🙏💯 I got my unit called " ENI PS 600" I Don't know what software to use?

Your videos are always excellent and well presented but I'm not so keen on this sampling method because of the risk of damage. I know you warned about this more than once but I think it's a bad method to advertise to others because it is so vague and tuner specific. Your other RF sampler videos use much better defined and safer methods. RF damage to test equipment is always a worry and I use various methods to minimise risk such as diode limiters and even RF fuses inline with the limiter.

For use sampling the HF frequencies, what are the minimum specs for an oscilloscope? Can any of the inexpensive USB scopes suffice?

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Interesting. I think I would put my real outputs as 1 and 2. Without switching by the scope. Thanks I think I will try this or something similar soon.

Great idea and very useful! Would you consider a video on how to read the displayed voice signals, in order to properly set microphone gain / compression? ( I use my rig's ALC meter, but leaves me wondering about what's really going on! ) Is there any chance an Eico 350 wide band scope can be used? Thank You!

Hi Alan, not sure if you check these older videos for comments, but I picked this one as I see you have the same model here as I do: I recently picked up my 2445B and am very impressed with it so far. However, the real reason I'm writing is to comment on your very extensive range of analogue (and digital) scopes - you seem to have a never-ending supply of differing models; besides the 2445B featured here, I have noticed also a 2467 and a 2465A CT (no doubt you have many more than just theses 3 models). I was wondering: could you do a video on what each of these scopes brings to the table for you, their unique characteristics, etc? I know from Dave Jones on the EEVBlog that the 2225 is special as it can display down to 500uV/div (I guess you have one of these too, but I haven't seen it yet for sure). What are some of the features of the other models you have to make them special in your workshop? Perhaps you could do the same rundown for your collection of digital scopes too. That is unless you've already done this and I've yet to come across it. PS. Hope your ankle is fully better now!

Couldn't you just install a BNC into the back of the radio with a dead short near the RF output and have the same effect?

Hey, I've got a 2445 too but it has a problem. The Li-ion backup battery won't keep a charge. It's 3.6v. For a quick test I tried CR2032 and it drained very quickly. I've also replaced it with the exact part for about $30 and still no joy. The symptom is it requires that I acknowledge the error every time I switch it on, it will not hold settings and the bottom line of the display fills with "?????2v???????????1mS????????????". Ever run into this?

If you used a 100 watt light bulb for a dummy load would the bulb flicker to the tune of the signal or would it just glow at a steady rate.

Hi there! If we decide to operate with limit power “1500 watts” can that be affected by creating high level of RF into the scope. Can the scope be damage?

Hello. Thanks for the video. I transmit am signals from raspberry 3. The max output power is 200mW. Can I plug it directly to my scope? Or I need rf sampler? Thanks.

Would this work with an antenna switch box as well? It should in theory

Another cheater way to do this is to take a few turns of wire around the coax feed to the antenna.

Do you think an unused port of an antenna switch would work? Thanks Larry…WA4PJP

but then you got to buy more expensive equiptment

That neat ng9p

You should be sampling off of a dummy load and not going directly into your scope

Absolutely useless for any practical purpose.

I'd like to display a trapezoid on my Tektronix 2465 BDM scope. I've got the sampler and de modulator but can't see where I input the X and Y in ch 1 and 2 to get the vertical and horizontal display for modulation and carrier. Please, help...???