#51: Basic Spectrum Analyzer Do's and Dont's ... 

as an OLD newb, i'd be screwed without your videos. many thanks

I really appreciate your videos. After a long career in the wireless industry where our labs were full of expensive hp/tek boxes, I'm setting up a home lab and sorting through used vna's and some newer siglent/rigol... boxes.

Here is another good tip to avoid blowing it up, don't use is as a workshop broadcast receiver as one day you will go home for the weekend and leave the outside antenna connected and it takes a lightning strike. Great channel.

This was extremely useful, thank-you! It's good to understand the "why" of taking safety precautions.

Subscribed and watch alot of your video's and have not found any errors yet. You really know your stuff. Love how you break it out on your excellent hand written schematics too. Sometimes I need a refresher and your my choice. Best video's on Tube. Thank you.

I just got one of these at a good price but the 50 ohm model. Great to see this video. You gave me the info I need to keep it in good working order. A lot to learn yet, but covering the fundamentals is always good, no matter how much I learn. Thanks for all of your videos.

Thanks a lot for your reply! After watching this video I watched "Use the scope to measure the length and impedance of coax" and I understood what was going on. Thank you for this free knowledge!

Thanks for these awesome videos, sometimes just doing the basics over again is a great fundamentals refresher. I always learn something from these no matter how simple they may seem.

Another great explanation, a very good video as always. Many years ago a colleague had a natural gift for blowing up spectrum analysers. One type of measurement we did at the time was mains borne interference, we used a form of high pass filter that you could connect a measuring receiver to. Of course the merit of using a receiver was that the tuned circuits in the front end effectively integrated out mains borne spikes, and the full transient amplitude did not reach any of the active devices. To my knowledge he trashed the mixers in 3 spectrum analysers, one after the other. For general engineering purposes it is probably good practice to keep an attenuator permanently attached to the analyser, that way you think twice about removing it. My own spectrum analyser would not justify a massively expensive repair if I damaged it so I have to look after it! Thank you again for making some excellent videos.

Great presentation. Thanks, Barry

You are a great teacher. Thanks a lot for your dedication to teach.

Great Informative Video, a critical reminder at the least. thanks for the contribution.

APU. Great video. Thank you for your dedication in teaching (entry level) people like me. Thank you immensely, David

Thank you =) I’m getting my first SA (HP 8560E), and found your advice very helpful. Looks like I need to get a few DC blocking attenuators!

Thank you for such a valuable information.

Great video. Extremely useful! Thank you.

Its really useful video, it helped when i worked in a satellite station as a freshman

Thanks for the good advice sir. Most appreciated.

Thank you! There needs to be a complete series on "How not to blow up your..." for all of the common analysis equipment.

Alan, thanks for another great video. How does the input float voltage limit (+/- 4v, for instance) relate to maximum signal input voltage on a low frequency instrument with high impedance? I can't seem to figure it out. Ken

Have you seen a product called “RF SNITCH”? It’s a tiny device that is powered by USB-Micro power and has a single SMA female connector. The housing is clear and permits viewing of the internal LEDs. There is a green / 2x orange / red.. I believe they are bi-color or tri-color LEDs because upon “alarm”, I recall they all turn red. You are supposed to connect this to the device you intend to connect to a spectrum analyzer or VNA. If the signal is low enough to use safely with the sensitive test gear, it will light up GREEN. and… you can guess the rest of the operation. I’m not sure about signal levels, but it was reviewed and recommended by RU-vidr IMSAI Guy. (around $50 bucks or so.. I bought mine a year ago and can’t remember the exact pricing) Another great video..Thank You!

Good information, thank you! 👍

Cool video, thanks for sharing. Do you know much / could you do a quick video on using a spec an to align a ku band satellite?

Very nicely done. Nothing too techy, nothing too dumbed down (for me at least) Just got a spec-ana. Trying to figure it out. (and un-teach the o'scope view)

Tektronix recently came by our shop and demo'ed an MDO4000. OMG what a machine. have watched all your MDO's. More MDO please lol.

i am glad you provide such a interesting topic from the theory to practices,can you be kind enough to make another movie and show us how to use spectrum analyzer; i like to know the relationship of RBW and VBW; thanks in advance

Thanks for putting this up.

Thanks Alan, answered all my basic questions in one go, another great video, I will add an adjustable attenuator to my shopping list ;) How much attenuation "span" do these things give, and what's a good range for general in the shack amateur usage? i suppose it depends on the input range of the analyser itself? Cheers :)

Be careful with that 30dBm level for maximum input power. That apply to the front end attenuator. If you set 0dB attn and apply 30dBm you for sure will damage the front end amp or mixer. The front end mixer typically should get more than 0 dBm for safety and for optimum measurement of linear amplitudes should be below -10 dBm. For non linear amplitude (harmonics, intermodulation...) the power to front end mixer on most Spectrum Analyzers (including Agilent ESA) should be around -35dBm.

very informative subscribed

Thank you for video.

You see from my previous posts that I am alway talking about internal and external attenuator. The general practice is to always put external attenuator (10 dB typically) as close as possible to you measured device. That specially true if you have to use long cable or the Spectrum Analyzer internal attenuation is set to 0 dB. Such approach will improve matching between your device and Spectrum Analyzer. That very important for measurement of non linear parameters (intermodulation, harmonics).

Hi there would it be possible to do a tutorial on scale fidelity measurements on a spectrum analyser or could you direct me to a video?

Great video. However I think there should be mention that dbm measurements will differ depending on the load. Measurements in 50 ohm, 75 ohm and 600 ohm (telecomms) will be different particularly with respect to the voltage. For instance a 1mW reference power level corresponds to 0.224V in a 50 ohm system, 0.274V in a 75 ohm and 0.775V in a 600 ohm system.

Great video!!

Nice video, very informative. Now I can play with my Rigol DS815TG

Do you know how to test RF devices, such as a Bluetooth device, WiFi device? Are you familiar with FCC testing procedures or ANSI C63 procedures?

Excellent videos :)

Superb videos many thanks, How about a tutorial on the accessories that maybe needed, as this is a bit confusing for the newbie like myself.Im taking delivery of my first real spectrum analyser in a few weeks, so i have gone out a bought a few items like you suggested - DC Block, and a few 10GHz JYE BAO N Type attenuators. But a sampler?, whats this used for exactly? and bias Ts, Splitters, Combiners, Loads, this stuff has got me, when and why to use,

thanks please put more videos it is very helpful Thanks .

I GOT IT! LT Spice has been the only one I've had luck with so far but I did use a *.cir file.

I have a question around spectrum analyzer safety, power levels and preselection: Must the Reference Level always be selected according to the strongest input signal (to not potentially cause damage)? Even when its currently sweeping a different frequency range on a much smaller signal? (my gut feeling is "yes", because 1st mixer will still get everything, so the attenuator should not allow too much of the strongest signal to the mixer - which would also mean that a "peak zoom" function may be dangerous to use on smaller signals - because it'll adjust the overall reference level to that small signal's power) Thanks!

Excellent! Thanks!

Thank's for this video, i have a question about the input power, since there is an internal attenuator, does +30 dBm of the maximum input RF power refers to the maximum power when internal attenuation is set to 0 dB, or whatever internal attenuation these +30 dBm should not be exceeded ?

That unit was made for CATV/MATV. Line amps are phantom powered at 60 volts and on 75 ohm coax.

Are there any books you recommend that explain exactly what you described as far as setup and taking basic measurement using a spectrum analyzer?

More! More! ... :) Can you do a video on typical Amateur Applications / ... like 'full spectrum' info. (sorry for the pun). Thank you & 73, Neil, K7WK

Just bought an Agilent E4411B and I wanted to know where you got the 75 ohms to 50 ohms Minimum Loss Pad. I have seen them cost 200-300 dollars and more. I'm on a budget. Oh BTW, great video. I am so glad I found it.

Good video ... thank you

Great video. Wanted to know if I can relate the span nob on the spectrum analyzer to the LO frequency range that will be selected

Thanks for the video. Quite informative. couple of questions: 1) if signal is close to Noise floor do we still need to move the whole spectrum up on the Y axis so that the signal peak is just below the reference level? 2) for default attn of 10dB i get some power levels (say -60dBm) but when i increased attn manually to 20dB and beyond the power level moves to-74dBm. Does this mean the 20dBm is optimum attn.? which power level and which attenuation i should trust? Thanks

Thank you very much for your useful video. I am going to measure the frequency of composite by vibration techniques(impulse frequency) for mechanical properties evaluation. I would like to know I can use a spectrum analyzer for this problem. could you please introduce me a portable or handheld spectrum analyzer? Best Regards,

Could you explain to me what it's for 50 ohm terminator at the entrance to the spectrum analyzer? I do not understand why they put 50 ohm terminator on the input of the oscilloscope too? Anyway, thank you for these wonderful tutorials!

Hi Sir, you mentioned about setting the reference level causes the attenuation to be adjusted (under auto mode). Let say the attenuation is auto set to 10dB. So does that mean the peak value reading we take from the screen is already attenuated by 10dB? If that is the case, we need to add back this lost in our final value of the power received?

Can you recommend any videos or video courses for learning the basics (and even more advanced topics) related to of spectrum analyzers? Also .. can you use an Anritsu MT8820C for the channel? ( 30 MHZ - 2.7 GHZ Radio Communications Analyzer) It’s fully functional and was give to me by a friend’s wife after his passing. I initially wanted it for spectrum analyzer use but discovered it couldn’t be used as a standalone SA. So.. it’s just gathering dust.

Brilliant information, after rf attenuation should the spectrum analyser proceed the osciioscope or doesnt it matter? Cheers Andrew

Love your videos. I have a question on the video. I see you are using a 75 to 50 ohms pad. How does this effect the output? Also could you use the pad on say on a sweep generator? Thanks and keep up the great work.

Thinking of purchasing an analyzer soon. I kept up with ya on most of the video, however at the end you started pullin' ahead...lol.

Great info! Think you could do one on measuring channel power?

Yes thats what it is. The repeater is for a particular cell carrier but it needs higher power because off the building where the phones are being used and is shutting down another adjacent phone carrier, can a band reject filter be used in this case? Because the repeaters dont have any internal attenuation nor gain controls.

Fast Fourier Transforms. Could you recommend some material for my level having not yet gone all the way through Calc. got in a fight with the book due to misprints.

Is there anything you don't know LOL! Awesome video!

Alen can you use a basic spectrum analyzer to see interference caused by a cell phone repeater and if by reducing the power of the repiter can all the interference be totally eliminated also what types of interference can the cell phone repeater cause? thanks.

What I marvel at is your command of knowledge in using such instruments. I wonder how did you learn to use such instruments to the level you know how to use them? Did you study the owner's manual or were you taught by someone and learned your way through that?

Hi, is there a certification we can get online for Spectrum Analyser Operations?

It was Carl Hanck. I could really use it for Quam & CODM investigation. Do alot of that. Few months later I see Tek is selling the same box for $7,000 on ebay. Wish I could afford it personally. But I already own a alot of test equipment.

Is it Radio Frequency Interference if I hear an unusual "Hum" sound in a video. (This sound is heard as clear as if it was part of the video, but the first time I saw that video, it wasn't there)

Following my previous post: Spectrum Analyzer optimum measurement power apply to the internal mixer not the the front of the Spectrum Analyzer. So if you power from the device is let say +10dBm and you measure fundamental frequency amplitude than the reference should be set to +10dBm and the total internal or external attenuation should be more then 20dB. If you measure intermodulation that internal or external attenuation will need to be set to 45dB.

👍Thank you sir.

Howdy!, I recently won a Tektronix Model 491 Spectrum Analyser, from eBay, which appears in perfectly serviceable condition, (though I have never powered it up, yet), but I have had zero hits searching for manuals on it: even Tek's website gives no joy. Have you any clues to acquiring manuals for this piece of exquisite T&M aparatus, or hints I can use to bring this puppy back into service? (The listing said it had been recently used, by the owner, and worked satisfactorily, at least up to 2.5 GHz) I would appreciate any hints you could offer. Your tech vids are among the very best I have EVER watched! Keep on Keepin' on (from a 60 YO fossil engineer). Cheers, Dave

I've been binge-watchingh some of your stuff lately, I'm a noob in RF and electronics. My question is can I get these kinds of adjustments (span, center freq., resolution bandwidth...) out of the FFT spectrum analyzers built into cheap scopes (say $500 to $750)?

I hope that you please will answer this question. I can read that Spectrum Analyzer often goes from i.e. 9KHz and up, but what if I want to look at an audio signal at 22Hz?

picked up a used Rohde & Schwarz CMU200 off ebay for $800. RF input safely supports up to +47dbm, pretty unbelievable. and a nice safety margin for me! also means i don't have to worry about non linear response through any attenuators for most of my work.

HI W2AEW. I am planning to buy a service monitor for two radios but I would like one which would have a scope, spectrum analyzer. As I would like to use it for service the two way radios and to tune duplexers. What would you recomend. Also that it is not so expensive.. I will be waiting for your response. Thanks

Hi there, I wanted to ask if it’s okay with you if I show some of these videos as part of my own twitch stream. I just received my first analyzer and I think it would make an interesting stream to show my „first steps“ with the device, using your videos as a guide. So it would be watching/reacting to a part of your video and then trying it out myself. Thanks in advance, and many greetings from germany :)

Question: just got a RIgol Spectrum Analyzer with tracking generator. Tuning ham radio duplexers, I noticed that when I manually change from say 550 ms to 5 sec sweep time, the point of tune changes. Is there an optimum setting that is best for this kind of work? Also noticed than there's not much change from 5 seconds to 10-15 seconds, but I want accuracy, not speed....suggestions?

So a Signal Analyzer can view the frequency base of a signal as a Spectrum Analyzer does but it needs to convert it from a time base first. So a Signal Analyzer would be more useful in Electronics?

Hello W2AWEW! What happens in the case that I have two tones, assuming that both are 5MHz apart and where the tone of interest is much lower than the other. Does setting a narrow span perform a filter behind to suppress the higher tone? This is important for me because I want to measure the lower tone accurately without over ranging. In general, when we set the reference level, is the gain applied to every tone the spectrum finds or only confined to the span of interest. Thanks alot

Hello. first of all, thanks a lot for your knowledge condivision about this amazing equipment as a SA is. My question: a 75ohm input impedance equipment is suitable for learning or you misadvise to buy it to a beginner as I am. You are right when you say that you could get it as a really bargain, but due to it would be sure the first but the only one, I would like to buy something which could be useful at all, not only for some nice intelligence game and to leave it off for unsuitability at all. Thanks. Danilo

Thank you

I would like to reproduce the graph in my AC book. I know I've probably gotten a little off the path for an electronics student but the Spectrum Analyzer relates to so much science and physics I had to try it out. I'm probably not setting it up properly though to start out with. I've tried 5 Spice and Tina 9 with no results. Any suggestions would be helpful. 3H |----------nnn-------------- ~ 1V 60Hz RL 1k ------------------------------ Thanks.

I see the small spectrum analyzer you have only accepts -30dbm or 1 milliwatt, is there a way without a power meter to measure the 1 milliwatt before you attach it? Could you use a multimeter on ac amps?

Hello, I am looking into getting my first spectrum analyzer for transmitter tuning and repair. I have my Bird43, the 4275 line sampler, 2205 scope and dummy load. What I would like to do is add my frequency counter and a spectrum analyzer, could you describe how to do it? Perhaps one of your great diagram layouts.Thank your channel has inspired me.

What do you think of using a general coverage HF receiver and modifying it with a swept VCO and also sending the output of the ramp generator to the horizontal input of an oscilloscope. If not where can you get the RF/IF plug in lke you have thanks Jim KD7TU

How can we test nonlinearity of a spectrum analyzer for L1/L2 band?

If you don't know the frequency you are measuring, what is the quickest way to determine the frequency? Do you just widen the span and adjust the reference level as necessary to detect any weak signal?

thanks for the video...please can anyone give me a link and/or tips on how to measure 1/f noise using a signal source analyzer?

need your advice I bought a used HP 8981a Vector Modulation analyzer without any manual hoping to use it on audio tuner debug. Did I buy the wrong piece of equipment and it looks like I need to purchase a high freq generator. First time i've purchased this kind of equipment and need some help. Thanks

Hello I have a complaint... these Agilent SA make froze when use GPIB, is a good instruments but in my experience works better oldest HP, I was worked in some electronic labs and I prefer old HP SA, the model of these video works fine but manually not in remote mode like latest models, guys if you know how to prevent these please tell me what I can do, regards!

When you lowered down the RBW, the noise floor dropped down. When the noise floor dropped down, what is its effect on the peak of the signal? Did it change as well or did it stay at the same reading?

Can this spectrum analyser detect GSM signal boosters? If yes... Please, explain and how it works. If no, please tell me the equipment for detecting GSM boosters in an environment. Thank you all for your input.

excellent.

good video

Cal you make cheap rf spectrum analyser using crt tunner and Arduino ?

So, if I build a 2m Ham Radio at an output of the typical 5 W, I would use the external attenuator to reduce that input power (voltage) down to 0 V? How does a spectrum analyzer be designed to only handle a 0 V input when RF in the air is typically in the micovolts range (I do understand that wave forms above and below 0 V cancel themselves out to 0 V. Is that the theory here?) Frank Frank Reiser Video/Audio Service

Hello W2AEW, is it possible to measure phase of a signal on a signal analyzer, if so could do a demonstration of the measurement.

Thanks nice Video

How can you use a spectrum analyzer to measure CCTS? Somehow you can calculate the Crew Curve of the audio signal by knowing the resonance frequency and the speaker frequency start and stop range. I'm not sure what the crew curve is used for

what happens if you connect a spectrum analyzer in parallel?

I paid $500 for my 8565A from my neighbor who used to own a Wireless Internet company. Best $500 I ever spent! very handt piece of gear too.