#296

[@ohaya1]

Thoroughly enjoyed this! I think this video should be seen by every ham in training.

[@andrewlit2202]

Alan, just want to thank you for the years of high quality content. I started watching when I was 12 or 13... Now I’m nearly done my degree in EE, and your videos have certainly been a part of keeping me inspired to follow this path. Keep up the good work!

[@Jan_Talcott_100]

What a wonderful job you do explaining this topic. You drawings and notes are excellent!! Thank you.

[@bobkozlarekwa2sqq59]

I’ve been subscribed to your channel for about a year, and I look forward to very new video you release. I also follow a few pages that you follow such as The Radio Shops page and TRX Workbench. I’ve been licensed since 1970 and have remained somewhat radio active throughout that time. Your videos have taught me some troubleshooting tricks and techniques that have resulted in getting me into a restoration mode. In the past when I attended a hamfest I’d avoid radios and test equipment that were in a visible state of disrepair. Now, I look for them, so I can restore them and give new life to an old faithful piece equipment. 90% of the repair process is usually replacing failed capacitors. Just wanted to say thanks for all your hard work!

[@AcctistaZ]

To every viewer of this video (i assume many are students like me), please remember to exclude w2aew from your ad-block list. If you want high quality content such as this, support and give motives to this guy

[@migsvensurfing6310]

What about disabling it completely so YT stays free ...?

[@DennisSantos]

Absolute quality video

[@rocketryguy]

I just stumbled onto your feed via a google search, and I have to say that at least on this episode you do an excellent job of presenting. This is a distinct skill beyond comprehension of the subject matter (which you obviously also have). Your clear, and most importantly succinct, presentation of this stuff is top notch. Looking forward to seeing what else you've done on your channel.

[@w2aew]

I hope you enjoy my 300+ other videos as much as this one.

[@lalchandra4590]

This person has amazing teaching quality. I worked hard to understand smith chart from class lecture. But Alan's video help me alot.

[@cbradiomizfit7562]

Yessir i agree

[@VK2XXL]

So many people think their rigs are only doing like 30 or 40 watts. The old Kenwood hybrids were very conservative with their PEP which is why they sound so good on the air. More people need to see this. 73 from Andrew VK2XXL

[@paulbaker9277]

As a new ham in VK land with a F licence, thanks for your video, when I can see the process , even though I read the literature, a visualisation helps a lot in seeing it set up as you talk through it.

[@paultomasetti5164]

More please! Things like discerning between good and bad modulation envelopes. What makes them bad,what makes them good. I feel that I don’t know exactly where I should be looking. For example, I here the phrase going into compression. Some people will be pointing to the peaks and some,the troughs. Should I be focusing on the very outer edges? Or the very center where the shaded areas are coming together. I hope my confusion isn’t rubbing off on anyone. If you already have more video on this, I’ll find it and you can disregard my question. You’ve definitely made things more clear. Thank you for sharing your knowledge.

[@rabbibacongrease88]

This is one of the best videos I've seen on this subject.

[@StefanGeets]

While studying my ham radio exam I got confused about these concepts. Your video brought me clarification. Great! Thank you !

[@brianwhelan5093]

Hi Alan, what a wonderfully factual, visual and practical video for all (experienced and the not-so-experienced!!) to use to understand a topic that is not too often discussed. A pleasure and so easy to watch as per usual; well done! Brian EI8EJB

[@octavmandru9219]

Absolutely superb explanation, as always. Thank you Alan for enlightening some aspects I was missing before I watched your video

[@jeffryblackmon4846]

Every ham can learn something from this video. Many thanks and 73.

[@bobgilliland5095]

Excellent video Allen, as you always do. This video answers that big question as to whether the transceiver is putting out proper power levels, as many of us ask ourselves. I would like also to see the addition of the effects of the transmit ALC influence, particularly in regards to digital modes. I really enjoy your videos. Thanks, Bob K3TCT

[@johnclarke2997]

Takes me back to broadcast engineering training when I was training to work on the maintenance of broadcast transmitters which ranged from a couple of watts up to 500kw in all broadcast bands. Transmitters tend to have a duty cycle which says for how long a AM transmitter can run 100% modulation before the power amplifier starts to overheat and shutdown, but as the modulation was fairly low and normally music and voice the transmitters seldom if ever go near the duty cycle rating. Many amateur radio transceivers have a duty cycle figure which for a quality transciever will be shown in the manual or the specification.

[@MattEugene]

this helped me understand my cb radio swr/power meter and why it was only showing an average rated reading of less than 10 watts while talking on ssb. it doesn't mean that the radio is not putting out it's full pep, which is reassuring.

[@rasherbilbo452]

So glad to see a new video from you. Happy new year!

[@DonDegidio]

Hi Alan, You have a knack of making these topics easy to understand with the visuals you use. :-) 73 WB3BJU

[@DucatiMTS1200]

Thank you for explaining. Most appreciated. I have been studying your tutorials and building your circuits to help me better understand. I'm having so much fun since I took up amateur radio. Thanks for your precious time and expertise.

[@ElmerFuddGun]

Interesting how the IC-706 power output meter jumps around with AM (10:05) and two tone SSB (11:00) and isn't constant like the Bird meter. That can add to the frustration when you can't trust the meter. Not just the 706 of course.

[@tommybewick]

Great video, I'm just studying for amateur extra class and on the section of PEP. Great explanation. 73, Tom

[@W1RMD]

Excellent demonstration! I love the Icom 706 mkiig. 10 years of excellent service for me.

[@-Todays-Tom-Sawyer-]

Great video as usual Alan. The single tone method using my frequency counter you taught me is how I tune all my SSB boat anchors. I have told many other hams about you and many use that method. Great stuff. I have a Drake W4 watt meter in my shack. I would like to learn more about adding the peak responding circuit you mentioned. 73s KF6HF

[@w2aew]

You might take a look at the PDC-1 - it might be adaptable to the W4: www.hi-rescom.com/html/pdc-1.html One of the reviewers on eham put one in his W4: www.eham.net/reviews/detail/999

[@berndb.5097]

Of course, the Drake W4 Wattmeter is not a low end part, but the conversion which Peter describes here kzbin.info/www/bejne/g6WTcmSehsSoiJI is also valid for this. In any case, I have rebuilt my W4 exactly the same way and it works flawlessly. 73 Bernd

[@boxingday11]

Excellent explanation, well explained, thank you. Best regards,Carl .

[@DavidS-iw4ei]

Thank you I learned something new today. And you reinforced what I was thinking.

[@josephriffle124]

Great video. It gives me a better understanding of SSB power, and be able to make proper adjustment(s) on my radio. I continuously use a oscilloscope on the Antenna output to see the envelope.

[@prepr8725]

excellent content 73 🎉

[@carldavis8228]

I like that PTT to control keying and SG input. Simple yet elegant. Need to build one myself. Also, I always relearn something old. Your tidbits add chlorine to my old knowledge pool, which over time has become tainted with algae and needs cleaning out. Thanks!

[@archtechgr]

100k congrats

[@AD4MRick]

Excellent explanation and very nice examples. Thanks for the video. R

[@iammrhellohowareyou]

I recently picked up that fancy drawing tablet tech you're using in this video. Took some notes with it on some of your lesson videos earlier too!

[@nickolaosv1397]

Very nice video. Those days i am building an ssb tranceiver and i realised that there arent any videos about that modulation.

[@peterb8387]

Excellent video !

[@Orvulum]

Great illustrations!

[@jorgemaciel9290]

Buenisimo el video bien educativo muy bien explicado y mas tratandose de radios lo felicito hasta me motivo para comprar un osiloscopio para envolverme en reparación de radios hf

[@MBJanus]

Many thanks for your explanation. A lot of "spécialistes" in France try to let believe the owners that their TX need to be adjusted and I saw one who wrote he can increase the power by modulating more than 100% in AM mode.. with no distorsion aso. This one no more let ask pubicly about this kind of claims.. Thx again, sincerly yours

[@MobiusHorizons]

Thanks for the very clear descriptions!

[@TheDefpom]

Nice explanation and demo, as always.

[@rolandosalgado1552]

Very good explanation, thanks for share!!

[@Diki58]

Hello Aln, you said : "A peak-reading Bird (or other quality meter) can certainly be used to measure the peak envelope power of an AM signal. PEP can be as high as 4x the dead-key power (for a properly setup 100% modulation." The simplest way to visually measure the modulation power levels in AM/FM/SSB is to use a DIGITAL SWR METER capable of being configured either in "Average power", either in "Peak power ('PEAK'), either in “Direct Power”, either in "Power Before Modulation”. For example, the MFJ 826B DIGITAL TOS-WATT METER allows you to measure these different types of “power”. Do you agree ? Sincerely

[@w2aew]

A meter designed for peak reading should work well.

[@JeffLeites]

Great video. I would have been interested in seeing the watt meter responding to your voice in AM mode. K3OHU

[@stompreaper]

This was a brilliant video. More like this please!

[@legionaire4017]

I really liked this video, thank you for sharing! Are you using just a 10x probe in this example? I'm just curious about what's necessary for input protection. I'd also like to see your explanation of bessel functions in FM modulation, not sure if that is something you'd take the time to create as it certainly would take some effort but I think I speak for most of your viewers here on KZbin, you are an asset to the electronics and amateur radio communities and we are very grateful for your hard work in making these excellent videos!

[@w2aew]

Have you seen my video that discusses FM deviation measurements using Bessel Null? kzbin.info/www/bejne/bnqlgIylfrtoo5o ...and yes, I was using a 10x probe. You'll have to check your probe's ratings to be sure of the safe operating area.

[@pd1jdw630]

Good explanation. Thank you. Could you maybe do a video on the Weathstone Bridge regenerative receiver? As build by N1BYT? I can’t seems to grasp how this actually works. I’ve build it, it works. But I’m still a bit baffled about how.

[@timka880057]

Enjoyed the video! Understandable, you said effective and it reminds me of the root mean squared of AC. effective value of AC.( .707 times the peak or 1.414 the rms) If the meter was quick enough to read it in real time it would be accurate. RF carrier is fast according to what frequency it's tuned to. The lower signal which modulates or rides on the carrier.... I imagine it has an effect on the carrier... like harmonics ( I play guitar so I know about harmonics)..... But both average out mathematically, (I'm sure there is a formula!!!) If it all was converted to DC with a rectifier it'd be double on the top reading on the scope right? Or eliminated to one half the signal on top. And if a L or pi filter, an inductor in series with one or two capacitors to ground, (a resonant filter tuned for that frequency) the carrier would be eliminated. Right? I've been watching you for a while. I enjoy your channel.

[@thomasgerstner8391]

Great video as always Alan. Many TNX for the Time you are spending for this Explanation,. 73s Tom DB1IAT

[@peterb8387]

Can you make a video showing the difference between a swept and real time spectrum of a FM signal sinusoidal modulated signal. I am specifically looking to see if there is always energy at each sideband always despite when the resultant sweeps across periodically.

[@w2aew]

The presence of the sidebands is a function of the modulation index (ratio of frequency deviation to the baseband frequency). Also, note that *no* spectrum analyzer can measure the spectrum at a specific instant. Even real-time spectrum analyzers need to acquire a vector of time-domain data to perform the fourier transform.

[@travised]

I appreciate how you explained PEP on this video. Thaks

[@cbradiomizfit7562]

Another perfect video I've been looking for. 👍👍👍👍❤❤

[@shaundickinson]

Very good video thanks for sharing the knowledge.

[@trevorpeterson8433]

thank you. I now feel better about how my radio is performing lol

[@bommel88]

As usual, a very good video. I really enjoy watching your videos. They help me understand a lot of stuff. Keep it up! 73 de DL6PT

[@MrJef06]

Great video

[@geckoproductions4128]

Hi Alan. GREAT video and explanation. I would like to duplicate your setup to help me retain what I just learned. Could you offer some detail on your RF tap off the back side of the watt meter to the scope? Thanks 73 N5RXP

[@w2aew]

I'm simply using a BNC-tee and a BNC to probe-tip adapter, similar to this: www.amazon.com/Cal-Test-Electronics-CT3655-Oscilloscope/dp/B009QBSKE2 You have to be sure that this fits your particular 10x probe. If you don't care about it being "calibrated", then you can use any number of methods to sample the RF. I have a few videos on RF Samplers that you might find interesting. These will allow you to get the signal to the scope easily. You could then do a simple calibration on your own (measure CW power and then calculate the response on the scope to arrive at an effective RF volts/division).

[@russellwillmott5637]

Wish the overmodulated splatter box idiots would learn from this, by far the best explanation of real power vs "bird watts " thanks!

[@Eduar-d-o]

Alan, awesome pre-COVID video Sir. I want to run the two-tone test in one of my radios but I wonder what each tone should be set in each generator in my service monitor. I was thinking one tone at 500hz and the other at perhaps 1200hz. I use 1000hz when performing single tone (AM modulation adjustment). Thanks!

[@billmoran3812]

Excellent video Alan! This shows exactly why so many so-called techs horribly mess up CB radios in the attempt to make them put out more power. I’m a firm believer in using a monitor scope to set the modulation level of a transmitter on AM and SSB. Also, a lot of hams don’t really understand that much of the transmitted signal in an AM station comes from the modulator in the form of audio power. A similar video regarding power measurements for FM and RTTY/ data modes would be good also.

[@w2aew]

FM and RTTY are both constant amplitude modes (both modulate the frequency, not the amplitude), so the RF envelope is constant.

[@johnblake4503]

Another interesting video thank you, can I ask how do you connect your scope to the output of your transmitter, would this likely effect the SWR / impedance seen by the transceiver ? In one of your videos you spoke about not connecting the output of your transmitter directly into your scope, on this video I am guessing this is what you were doing as you were seeing 200v 100w. Many thanks.

[@w2aew]

I was definitely NOT connecting the RF output directly to the scope. If you look carefully at the image at the 7:00 mark, you can see what I'm doing. The transmitter is connected to the input of the Bird wattmeter. The output of the wattmeter goes into a Tee connector. One side of the Tee is connected to another piece of coax that runs down to my dummy load (under the bench, out of view). The other end of the Tee has an adapter that accepts the 10x oscilloscope probe, and the probe is connected to the scope. i describe this over the next minute or so in the video. At 7:50, I zoom in a little more and you can see the probe adapter more clearly.

[@kevingray707]

Fantastic video. Give us more!!!

[@celsojunqueira]

Good morning Alan, what are the two tone frequencies you use for signal verification? is there a pattern in these tones or not? Thank you for your attention, Merry Christmas and a Prospero New Year with great health and peace. Bom dia Alan, qual ´são as frequencias do dois tons que você utiliza para verificação do sinal? existe padrão nesses tons ou não? Desde já agradço atenção, feliz Natal e um Prospero ano novo com muita saúde e paz. Celso Junqueira - PY2CEL

[@w2aew]

The actual frequencies are not critical - they just have to be in the audio passband of the radio, and can NOT be harmonically related. The ARRL uses 700 and 1900Hz.

[@baghdadiabdellatif1581]

@@w2aew harmonically related you mean, they have the same fundamontal?

[@ilanyacobi2918]

Beautiful explanation

[@tonyalmeda8220]

Hi Alan, thanks for this video at a perfect time for me as I'm trying to align SSB on a radio of mine. Can I ask, is the mic gain on your radio at maximum for this two-tone demonstration? I presume I should I have the mic gain at maximum whenever following an SSB alignment procedure? On the radio I am working on I get the SSB RF envelope pattern as shown in your video, but only with the mic gain on my radio turned barely a quarter of a turn. From this I have assumed the radio has been previously set up with too much gain and I need to back it off to show the two-tone RF envelope at mic maximum - would that be correct? The service manual states 30mV for both tones, which I've set, but i presume that if I lowered the level of each tone I'd be able to get the RF envelope pattern where I want it at maximum mic gain - but then I guess the audio output from the mic over SSB would be too low? Just a bit confused right now. I'm using a Marconi 2955B for the two-tone signal and wattmeter and separate 100MHz scope .

[@w2aew]

The audio and mic gain settings should be set such that the ALC is just barely starting to show deflection. You also need to be sure to adjust the levels of each tone so that they result in the same modulation level (sometimes the frequency response isn't flat in the audio path, so the levels have to be set independently).

[@tonyalmeda8220]

@@w2aew Ah! Got it - thanks.

[@gordonwedman3179]

Hi Alan. Thanks again for another great video. I have just started reading the section on PEP and ERP in the new ARRL handbook so this will undoubtedly make things clearer. Gong to try and read through the whole book over the winter☺️. What would you recommend for a scope adaptor? I actually have a 706 Mk2G sitting on my bench that I am going to install in my Land Rover, mainly for VHF but will also try HF. I might try repeating some of your video. Thanks again.

[@w2aew]

I have a few videos on RF Samplers that you might want to review.

[@gordonwedman3179]

@@w2aew thanks. I will carry out a search.

[@gordonwedman3179]

@@Willam_J Hi William and thanks for the recommendation. I have put that on my eBay watch list. Always good to know someone else has tried something and found it to work before buying. Cheers.

[@bobvincent5921]

Thanks for the lesson. Is the Bird meter a thermoelectric thermocouple type of movement as it seems to display a lagged response?

[@w2aew]

It is a diode detector type meter, but the meter movement has a fair amount of inertia and damping on it's own.

[@tormodberg6342]

Nice demo!

[@andrewverran3498]

Fkn brilliant video..is the input at scope attenuated or sniffed? Cheers. Blown scope

[@w2aew]

The RF is measured via a 10x passive probe.

[@andrewferg8737]

Question: How do you get a 100V envelope when Vcc is just 12V ? Is that accomplished using a step-up transformer?

[@w2aew]

Essentially yes.

[@combatwombat71]

Hi Alan, to make an real (actual) power measurement I assume I'd need to couple the 'scope directly to my RF, and not via some sort of pickup system eg. unused port on transmatch. Or if I did use some form of RF 'sniffer' method, how could it be calibrated? Tnx de Rob.

[@w2aew]

You can calibrate a 'sniffer' by putting a constant output signal (key down, unmodulated carrier, etc.) into a dummy load and measure it with a good power meter. Then you'll know how big the signal is on your scope for that power level. Of course, the scope measures volts, not watts, so the power reading won't be linear on the scope. A signal that is half the size (vertically) is actually 1/4 the power, etc. Remember too that the 'sniffer' response will most certainly be frequency dependent - so a calibration done on 20m won't hold true for 40m, etc.

[@soothcoder]

I love your diagrams BTW. The ones in this video were especially good but I also mean in general.

[@Frisky0563]

I learned a lot there watch this video. I appreciate the video so much I wish you lived near me!

[@azav8raa]

Alan, thanks for another awesome video. I had fun replicating the demo in the shack and discovered some interesting two-tone envelopes on one of my rigs. Do you have a reference of how to diagnose distortion seen in the two-tone SSB envelope output? Thanks again. -Andy KB7ZUT

[@w2aew]

No additional references at this time. Make sure to adjust the tone amplitudes for equal modulated response.

[@jbravovideos]

Very Professional Sir

[@athousandprojects]

Good to see a ReMarkable tablet being used - I love mine though just can't write a neatly as you seem to be able to! As always. great video :-)

[@w2aew]

The notes you see are usually the fourth or fifth iteration - or more!

[@dralive007]

Hi Alan, do you know what J2D transmission looks like on spectrum analyser? - are you able to upload a video?

[@w2aew]

www.sigidwiki.com/wiki/CLOVER_2000

[@vencentbauer]

Great video. So when iam checking audo..with my scope td.320 I would hook up to my antenna???

[@vencentbauer]

Ok I see throw the mic that spectrum analyzer i see very important or can u just use a scope ???

[@SmokeyWire56]

Take a look at the light i made. Is the RF too much?

[@plentygood422]

How do you get that to look so good on a scope mine is just one filled color

[@w2aew]

Your scope would have to support intensity graded waveform display - so it really depends on your scope.

[@emylrmm]

Very nicely done!

[@wa4aos]

Hi Alan, Always enjoy your well explained videos. Bob Allison, the test engineer for the ARRL came out with a book a few years back titled, "Amateur Radio Transceiver Performance Testing;" I suspect you have seen it. Some videos covering more detailed rx alignment and procedures would be great. 73, Glenn WA4AOS

[@w2aew]

I've got Bob's book. Good idea to produce some videos using these procedures.

[@rickvia8435]

Very good, presentation.

[@ElmerFuddGun]

Any suggestions for an inline sub watt power meter? SWR would be nice but isn't required.

[@electronic7979]

Useful video 👍

[@andrewferg8737]

Thanks for the education! Great video as always.

[@jangoofy]

Would this be a case where the scope function of envelope would be used ?

[@w2aew]

It could be, but not absolutely necessary.

[@jangoofy]

@@w2aew Interesting, as I have yet to find a real use for it :) - Thanks for the great videos.

[@davidedwards5461]

Just discovered your channel by chance, it's brilliant. Smith charts are awesome. Thank you for all the hard work. GM4GLG

[@radiostuff1026]

Very very good video. Thank you. !!

[@user-su5sq5ib3i]

Allan, I own a Siglent sdg1032x function generator and want to test my flex radio and Icom AM linearity and symmetry. How many mV can I safely inject from my generator? What would be the max voltage I would want to inject? I want the test to be realistic. Ive been trying to find this info in the ARRL handbook but cant seem to find it, I should add that I send audio into the line level input (100 to 600 ohms?) and the same to my 7300(acc port on back of radio). Thanks Allan!! 73

[@w2aew]

Typical audio signal levels will depend on the radio - but most are in the range of 5-10mV for most, a bit higher for rigs that use electret mics. You can start with something like 20mVpp and then adjust the mic-gain on the rig as needed.

[@user-su5sq5ib3i]

@@w2aew thanks I did some more research and found anything from what you said to 100mV depending on the input impedance etc. I do all line level inputs to my rigs so 4dbv

[@earleclemans4836]

Awesome channel 👍

[@MrFittyTucker]

Great video as always but I would like to see a video better explaining how these CBer's are taking a hundred watt AM carrier and reading 400 watts on their peak meters claiming that is the actual output power when the transistors aren't even rated any where near that by the manufacturer! At best you could expect maybe 10% more power because they were under rated to begin with!

[@eddyane67]

Great video! Thanks

[@hitechrr]

How did you make the box to inject the tone into the mic.?

[@w2aew]

It's pretty simple. A normally-open pushbutton switch for the PTT, and a resistive voltage divider to bring the signal generator output down to just a few mV, and then AC couple that to the MIC line.

[@robingist6666]

Hi Alan -- K4VU here. big fan (i binge watch your videos late at night). any chance you might be able to do a video on push-pull amp design and theory?

[@FXGreggan.]

Great video as always... but how in the *** did you manage to cut a probe in half? :) I hope it was intentional

[@w2aew]

Someone gave me the damaged probe for parts.

[@pirate959]

Where is the right place to connect the oscilloscope

[@w2aew]

To monitor the RF output, you would use some sort of RF Sampler. I have a few videos on that: kzbin.info/www/bejne/ZnzOkIGVidV3m9E kzbin.info/www/bejne/aHWbZKumaK1oeNE

[@Superzvision]

Greetings Alan, Thank you for your videos, electronics is always an interest to me and you do a great job of making it a comprehensible subject. I got a question for you if you have time. On an Oscilloscope, when do we use AC coupling or DC coupling and what does it do and Mean? Thank you in advance. 73. KD9JMQ.

[@w2aew]

I did a video on that. Excuse the video quality, it was done 7 years ago, before I had refined my video skills and had a HD camera: kzbin.info/www/bejne/fpzUXpmsl5pghKs

[@PaulZuhlke]

Which oscilloscope probe were you using?

[@w2aew]

It is a Tektronix MDO4000C series.

[@PaulZuhlke]

Thanks, but I'm referring to the probe, is it a standard High Z or something different, looked like an older probe connected to the tee adapter. @@w2aew

[@w2aew]

@@PaulZuhlke Oh, sorry - yes it is an older passive 10x probe, connected to the tee with a BNC-to-probe-tip adapter.

[@AcctistaZ]

This is useful for optical communications as well in some parts.