Going through a phase (on phase noise)

There seems to be a bit of hysteria on the alleged phase noise problems of the Si5351 chip.  The library yields some words of wisdom that help keep things in perspective:

ARRL Handbook (2002) page 14.5: "You would be excused for thinking that phase noise is a recent discovery, but all oscillators have always produced it."

Experimental Methods in RF Design page 4.12 "At first glance, phase noise sounds like a esoteric detail that probably has little impact on practical communications.  This is generally true."  (EMRFD does, however, go on to discuss the problems that arise on both receive and transmit from EXCESSIVE phase noise.)

Our old (young!) friend Thomas LA3PNA e-mailed on this subject noting that the Si5351 chip produces less phase noise than many Hartley or Collpits oscillator designs.   He provides a link to measurements (far better than mine!) of the noise from the Si5351:

http://nt7s.com/2014/11/si5351a-investigations-part-7/

NT7S puts it this way:

I believe that the plots speak for themselves fairly well. If you compare these results to the receivers in the Sherwood Engineering receiver table, I think you'll see that the Si5351 acquits itself quite nicely for such an inexpensive part. Personally, I think the Si5351 is eminently usable for many receiver applications, except perhaps the most high-performance. Certainly for the price, it's going to be extremely hard to beat. I hope this motivates those sitting on the fence to decide if the Si5351 will meet their needs.

Be careful in evaluating statements saying that the Si5351 phase noise is 3-6 db worse than an Si570.  This makes it sound like there is a LOT of noise coming out!  But again, it is important to keep things in perspective:  The noise from one chip might be -156 dbc/Hz while the "worse" chip might be -150 dbc/Hz.  That's still not enough noise to make a lot of noise about.  

The ARRL handbook recommended a very simple check for excessive phase noise:  Set up a very strong signal in the band of your receiver.  Then slowly tune to the signal, listening carefully for any build-up in noise as you approach the signal.  I did this, and I didn't hear any.  As for transmit, well,  as Pete points out, I think the spectrum police on 40 meters would let us know if our signals were broad or noisy!  The ARRL Handbook notes that in a transmitter, "This radiated noise exists in the same proportion to the transmitter power as the phase noise is to the oscillator power..."


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Si5351 Phase Noise? A Tale of 3 Oscillators

Si5351 at 16 MHz

 

There is still a lot of talk about the supposedly horrible phase noise of the Si5351 chip. In a recent episode of a popular (and very good!) podcast about homebrewing, the podcasters talked about this in the context of some megawatt AM shortwave broadcast stations that had oscillator phase noise problems and were wiping out large portions of the HF spectrum.   I don't think those stations were running Si5351s, but the listener was left with the impression that these handy little chips are very noisy with lots of spurs and will inevitably produce horrible dirty, spectrally impure signals. 

 

This has not been our experience.   Following Pete's lead, several of us are using the Si5351 to generate both VFO and BFO signals in our transceivers, with good results. The receivers sound very good and we have not heard complaints of "broad" or "noisy" transmitted signals.

 

I decided to dig into this a bit.  This was also an excuse for me to use the FFT and screen capture features on my Rigol 'scope.  

 

I now have THREE BITX transceivers in the shack.   My BITX17 uses a VXO at round 23 MHz (IF at 5 MHz)/  My BITX20 uses a classic LC VFO running around 3.5 MHz (IF at 11 MHz).  Finally, my BITX40 (DIGI-TIA) uses the dreaded and much reviled Si5351 running at around 16 MHz (IF at 9 MHz).   I thought that these three rigs would provide a good opportunity to test the scurrilous claims about the Si5351.   

 

As a simple first test, I put my Rigol scope in FFT mode and just put the probe at the VFO Mixer's LO input.  The screenshot above is the FFT for the Si5351.  It looks pretty clean to me.  The 'scope is looking at 15 Mhz above and below the VFO signal.    

 



VFO at 3.5 MHz

 

Next I measured the output of the BITX20 VFO at the same point (input to the VFO mixer).  (I had to change the vertical range, but the horizontal was unchanged.)  Here you can see the second harmonic (just because at this low freq it is within the freq range setting of the 'scope).  It doesn't look much different than the Si5351.   



VXO at 23 MHz

 

Finally, here is the BITX17 VXO at 23 MHz, again at the input to the VFO mixer.   It looks remarkably similar to the Si5351, don't you think? 

 

More on this to come.  The ARRL Handbook (2002) has a good discussion on phase noise. I am digging into this and hope to do some more tests.   For now, I think we should reserve judgment on the utility (for us) of the Si5351.  



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An Enthusiastic Recruit for the Color-Burst Liberation Army



Hey Bill and Pete

Man, I am loving the podcast! 

It is absolutely what I need, and what ham radio needs today!!!

I am at about episode 168 trying to catch up.

I would really like to build a Mighty Mite.

In fact, going on the record,  

I AM GOING TO BUILD THE MICHIGAN MIGHTY MITE.

If you have any crystals left could you please send me one.

I've got a 9 year old boy that's home schooled and I want to make this electronics hobby a stepping stone to a higher learning experience. 

I got in to ham radio to learn electronics and somewhere along the line I just learned how to send and receive CW and how to pass multiple choice question tests. Somehow along the way I lost my love of radio. I still have a nice modern day rig, but it has no "soul". I heard that comment in one of your episodes and it really rang a bell with me and when it rang I said,

 "Oooh, that's Awesome! "

I want a radio experience with soul!

I think that maybe why folks still use CW. It's a mode with soul. I know you champion SSB, but home brewing a CW transmitter and receiver has got to be a truly soulful experience.  And its one I intend to have as one of my own.

 I too want to enjoy the "Joy of Oscillation ".

With you guys inspiring me, I am sure this will be a wonderful adventure. 

THANK YOU! THANK YOU! THANK YOU!

For your guidance and inspiring work in the field of homebrew radio.

Sincerely,

Paul Hodges

KA5WPL 

P.S.

The chemistry of you 2 guys on the show REALLY remind me of Click and Clack. You guys really work well together! 

PLEASE DON'T STOP!

73

---------------------

Paul:  Consider yourself inducted.   There are, however, some conditions:

1) You MUST build the MMM and make it oscillate (thus experiencing the JoO).

2) You MUST send a picture or (better) a video of your MMM in operation.

3) You have to give me permission to put your e-mail (below) on the SS blog.

4) You have to send me your address so I can issue you a for-real SS 3.579 crystal (with mojo).

Deal?  73  Bill

-----------------

Deal,

I'll do my best to get video, at the very least I'll get pics.

As for making it actually oscillate, well if the "radio gods" let it be then I'll be having some good vibrations going on in the shack. Hope to have it going before first snow...of 2015...

Also, being inspired as I am, I made a CW contact with 5 watts since I emailed you last. 

Thanks for helping me get the fun and excitement and the adventure back in to ham radio!

Sincerely,

Ka5wpl

P.S.

Please send a card if you have one with the crystal. 

PPS  Also why not initial it if you've got a small enough pen :)

73

----------

Paul's Knack Story is here: http://www.qsl.net/ka5wpl/

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Star Trek Propagation Prediction

Thank you Brad Smith.  Live long and prosper OM.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Another BITX DIGI-TIA -- AC9JQ's (video)

Wow, Dean's BITX with Termination Insensitive Amplifiers (3 of them) sounds really nice. And this is with a homebrew ladder filter (see below).

 

I also like the way Dean makes his enclosures -- he uses scrap aluminum and 1/2" angle.  This might cause me to abandon the wooden cigar boxes.

  



Dean will now add the driver and PA stages and plans on following Pete's suggestion by making this a 20/40 rig. 

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VK3ZZ's Magnificent Rigs

 

Oh man is that beautiful or what?   Thanks to Peter Parker for the alert.   This is yet another reminder that Australia remains a bastion of homebrew enthusiasm and expertise. 

 

This is the work of Ross, VK3ZZ.   Read more about this rig, and the other creations of this Electronic Wizard (including an impressive AM rack), here:

 

http://www.qrz.com/DB/VK3ZZ

 

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The KJURKN Receiver (video)

Shell, WA6KJN, has built some really cool homebrew rigs.  And an airplane. 

On his QRZ page Shell writes: "I have saved all my old homebrew gear. This is a tube SSB exciter using a pair of 6146's in the final. It has a Collins mechanical filter. Built in the 70's. It had a matching receiver also with a mechanical filter in the I.F."

Check out the QRZ page for meore inspiration (and some good ideas on towers):

https://www.qrz.com/db/WA6KJN/


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Knack Story: Rupert Goodwins -- SolderSmoke in the Old Smoke (London)

Rupert with some sort of SDR rig

 

In addition to having a very cool name, Rupert Goodwins, G6HVY,  is a for-real tech guru:

https://en.wikipedia.org/wiki/Rupert_Goodwins

I was delighted when Rupert posted some sage advice about how to deal with my recalcitrant amplifier.   He managed to include a reference to Mr. Spock in his message, helpfully noting that some of these amp problems would challenge the Vulcan's logical powers.  That made me feel better.  I sent a few words of thanks to Rupert and got back this really great "Knack Story":  

Hi Bill,

 

Well, all I have on HF amp instability is anecdote and half-remembered theory. But I do like the sort of challenges that building RF on the bench brings up - a problem worthy of one's attention proves its worth by fighting back! 

I've enjoyed Soldersmoke (or should I say Soddersmoke) for years now, and even if I haven't bought the T-shirt, have bought your book. I first inhaled the demon fumes when I was barely into double digits, and the addiction kicked in hard - I fixed my first radio, a valve (tube!) FM 1950s broadcast receiver using a soldering iron that was actually one of my father's wooden-handled screwdrivers heated on the gas ring of the cooker in the kitchen. My parents were mystified but supportive...

London is indeed a hard place to play radio. But that makes it doubly pleasurable when it works: it rather feels like you're operating under cover, a special forces op sneaking the signal out under the noses of the regime. I once had a birthday picnic on Hampstead Heath where I brought my SOTA beam and fishing-pole mast: the local constabulary turned up and were also mystified but not quite so supportive... "What if everyone did it?" they asked. "Oh, if only..." I thought but did not say. 

 

I do hope you can pacify your errant amp. Sometimes these things can be fixed by brainpower, sometimes by just mucking around until they get bored before you do. But normally I find that I've learned a lot when the problem's solved. RF isn't black magic, it's a gateway into another world that's marvellous and enthralling, but ours to know. I read a really good paper by Freeman Dyson, where he said that Maxwell invented modern physics, because his equations were the first to show that the real world of how things work is both beyond our natural experience, but accessible through thought and logic. The real entrancing thing about radio is that it proves this - we can talk across the world by translating our knowledge into a tiny handful of otherwise inert bits and pieces that tap into something utterly beyond our senses. And it's open to anyone who cares enough to try. 

 

How cool is that? (I had to go and find that Dyson paper again - here it is, if you're interested:  http://www.damtp.cam.ac.uk/user/tong/em/dyson.pdf )

 

(I also have an unshakeable and unhelpful addiction for obscure but interesting radios, as my QRZ page confesses. And things I helped design and build when I was an engineer are now in the NSA and Bletchley Park cryptologic museum collections. That, as they say, is quite another story...)

 

Anyway, thanks again for emailing - I'm thrilled to hear from you, and perhaps, who knows, one day we may make contact the way God and Maxwell intended - via QRP on a lively band while dodging the noise and bouncing our photons off the Heaviside Layers. 

Best 73s,

Rupert, G6HVY

------------------------

Rupert's QRZ.com page contains additional evidence of his Knack affliction and International Brotherhood of Electronic Wizards membership:

 

Other equipment here includes a Wireless Sets No 19 Mk III, an R1155, a Barlow Wadley XCR-30, an ICR-73, some PMR stuff on 4 metres, some old CB kit (shhhh!) and other obscurities. I like kit that has something different about it the 19 set, for example, is of course famous for its wartime role, but it was also the very first transceiver. The XCR-30 is really interesting, not only for being a high tech product of 60s apartheid South Africa (so a morally complex thing to own), but for having a very esoteric design that provides 0-31MHz coverage without bandswitching, very high stability and accuracy (you can generally pre-tune an AM broadcast station anywhere on the bands from the dial and be within 1KHz on switch-on, and all from a handful of transistors. There are stories to tell about all of my radios. 

Started in radio when I was too young to get my ticket, so was forced - forced, I tell you - onto CB radio, in the days when it was very popular and very illegal. Had a couple of crystal-TX, super-regen RX walkie-talkies (QRPp and RX so wide I could pick up Radio South Africa on the BC 11m band) to start with, thence bought a 'for conversion to 10m' populated CB PCB from a batch at Plymouth ARC Rally and just bunged a set of toggle switches on the PLL-02 divider inputs. This was the mid-late70s, when skip was high... Did the RAE ASAP after my 16th birthday, first legal amateur rig (I may have built things with 6V6s that may have made odd noises on the local Top Band AM Sunday morning net) was an Icom IC-2E. My richer friend, who was a G6E, had an FT-290R, which was obv. nicer but obv. deafer. "FT-290. IC-2E. I can hear him. He can't hear me." Used 19 sets at school, so have that addiction too. Since then, the hobby has been in and out of my life (like QTHs, wives, jobs and money), but the love of radio never has. 

---------------------------

I also understand that he once worked at a dodgy TV repair shop in the back streets of Plymouth and can still swap out a gassy PL509 with the best of 'em.

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W1JSB's Very Cool Portable Rigs -- RadioSet-Go!

Brad Smith alerted me to this.  Very cool.   Hanz W1JSB is churning out some amazing trail-friendly rigs.   I really like the tinted-translucent front panel. 

Here is the site for Hanz's company:  http://radioset-go.com/

Here is his YouTube Channel:  https://www.youtube.com/user/w1jsb/videos


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Amplifier Woes! Instability at Low Drive Levels! (Video)

I have to keep reminding myself:  This is not "plug and play." These are not appliances. 

After I got my 40 meter problems squared away,  I was doing some testing on my beloved 17 meter BITX.   I noticed something weird:   With the CCI EB63A amp feeding my 17 meter Moxon antenna, as I raised the output of the BITX17 driver, at one point (at about half the max input power) the SWR would suddenly spike. Then, as I raised the drive level above that point, the SWR would go back to normal. 

I looked at it on the 'scope.   I can see the signal go very ugly at the mid-level drive point.  In the FFT display, I can see that there is a strong signal at around 435 kHz.  The 18 MHz signal seems to be riding along on top of it.  Take a look at the video above.

Additional clues: 

I see no signs of the 435 kHz signal at the output of the BITX 17.  It seems quite clean.

This problem disappears if I replace the Moxon with a dummy load. 

This problem does not show up if I feed the EB63A with my almost identical BITX20.   And I use the same LP filter on both 20 and 17 in the CCI amp.

Any suggestions?  Has anyone had this kind of problem? 

Allison and Pete have been helping me with this.  Thanks to both of them.  

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The 1Watter

There are currently only 2 in the universe.  And they have been talking to each other.  Soon there will be more.  Many more.

http://www.kitsandparts.com/1watter.php

http://www.1watters.com/

http://www.k7qo.net/onewatter.html

Chuck Adams explains (via the qrp-tech mailing list):
 

Aug 3 at 7:07 PM

 

Gang,

I and Diz have been playing on 20m with 1W.
OK, I've been playing. Diz has been working night
and day.

He has a kit coming out in two weeks or so. Don't rush
him. 

He has S/N 0001 and I have S/N 0002. These are the
only two 1Ws in the Universe. Yesterday (local time)
but 0000UTC today, I went to the lab to put a WWV
atomic clock above the desk for logging purposes.
I turned on the rig to listen while I put the screw into
the side of the shelf to hang the clock on. No warmup
drift. I'm tuned to 14.059MHz, the freq both Diz I start
out on and low and behold I hear him calling CQ. I pound
the paddle to call him and he went back to AF5XF in NTX.
Darn.

At 0031UTC I call him and I get a 229 and later a 339 and
he was a 539 here in AZ. So all the 1Ws in the Universe
have talked to each other. :-) The race is on, when and if
you get one to work us all. Or work us with the rig of your
choice and the power level of your choice....

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Amateurs and the Search for Extra-Terrestrial Intelligence

Interesting article.   The author mentions a connection between SETI and the Homebrew Computer Club:

http://motherboard.vice.com/read/aliens-in-the-backyard-how-amateur-astronomers-will-help-find-et

We had a SolderSmoke "SETI at Home" team.  Anybody know how are we doing?   

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Video of Curiously Strong Altoids Tin Frequency Counter

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Pete is Having Antenna Project Problems -- Can you Help?

Our friend Pete, N6QW, has run into some difficulties in his antenna project.   The push-up/tilt-over mast he is working with doesn't seem to be up to the task.  Just look at what this is doing to him!  

Does anyone out there have suggestions on how Pete might easily get his 2 element beam up to about 30 feet without spending kilo-bucks?

The project is described on Pete's blog:

http://n6qw.blogspot.com/

You could leave suggestions or ideas on Pete's blog, or in the comments section here, or e-mail them to soldersmoke@yahoo.com

Thanks.

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An Earlier Use of "Basta!" (MUCH earlier)

It turns out that Pete and I may not be the first homebrewers to make use of the word "basta!"  At lunch time, while sitting near the Einstein memorial in Washington, I found a short article in SPRAT 83 (Summer 1995).  In it, Robert PA3BHK presented some ideas for reverse polarity protection, and noted that his friend Peter PE1MHO had discovered an interesting phrase from antiquity:

"SPIRITUS TRANSISTOR BASTA"

According to Peter this was the diagnosis of a classical Roman engineer when checking a transistorized PA that went dead after an accidental reversal of the polarity of its supply. Above we see that same engineer, obviously setting up a 2 meter Moxon.  

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Pete Noodles a New Antenna

Big doings at the Newbury Park Lab of N6QW.  A new antenna is in the works.  Lots of noodling underway.   Much tribal knowledge is being dispensed (FREE!) via Pete's blog:

http://n6qw.blogspot.com/

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A "Curiously Strong" Frequency Counter

I got a six digit San Jian frequency counter for use with my BITX20.  I was trying to figure out how to put it in a box and mount it on the rig when I realized that the counter fits almost perfectly in an Altoids tin.  THE RADIO GODS HAVE SPOKEN. 

I found the counter on Amazon.  I use an eight digit version with my BITX17.  But I think the six digit version is better (it fits in an Altoids tin!)

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Pete has a Blog!

Check out the new blog from Pete, N6QW.   We hope he continues to post.   Please link to his blog and help spread the word.    Here it is:

http://n6qw.blogspot.com/

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Mikele's Croatian Belthorn Transceiver

Mikele's rig is a real "International Brotherhood of Electronic Wizards" kind of project.   The Belthorn design is out of England.  N6QW has added a lot of California influence.  The Nokia screen adds a bit of Finland.  And of course Mikele's excellent construction makes this a profoundly Croatian rig.

We love seeing rigs in their "out in the open " phase.   Thanks Mikele!  


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Dongle Update -- Dongles, FUNcubes, Meteors, QRP, and SPRAT

Hi Bill, Pete,

Ken Marshall G4IIB here the guy that wrote the SDR Primer in Sprat 162. I have been listening to your excellent podcasts. You guys cover a lot of ground in the May issue and touched on to the SDR dongle, its potential for future developments etc. I noted that you where going to buy another to cover VHF. Well if it ain't too late consider this New version by Newsky they are already getting difficult to get a hold of and are only available in the USA. It uses an R820T2 tuner (better LNA) an upgraded and stable crystal oscillator, a reinforced antenna coax and socket. The one I managed to get hold of also had a modified PCB with solder pads for the the Q channel (pins 4&5) to connect the toroid. Incredable at 22 of your Bucks. See the pictures and read all about it on amazon.com.

http://www.amazon.com/gp/product/B00QFCNNV0/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00QFCNNV0&linkCode=as2&tag=rsv0f-20&linkId=VNHED72IVHA5O2KT

All we need is for them to slot a 12 or 16 bit ADC in and we could have a truly great SDR receiver.

I noticed in your podcast you mentioned radio astronomy and satellite reception. Ironicaly back in 2013 this is how I started with SDR dongles. I read an aticle on the web on meteor scatter and started experementing with a dongle. Meteor scatter hunting is a bit like watching paint dry unless there is a known storm. So this led me on to the Funcube satellites. The signals from which although QRP 200mW are very stong and you can receive them on almost any antenna. The funcube dashboard software is available for free from AMSAT and alows you to download telemetry. You can also listen to amateur SSB an CW transmissions. There are lots of satellite tracking software available too. This then led onto weather satelite picture reception I built a 4 ele turnstile antenna for this but I found that I needed an LNA for reception at my location. I then started to listen to the amateur bands. Like you Bill I became interested in radio at the age of 11 and got licensed in the early 70's but work commitments  meant I had a 30 year absence from Ham Radio until I stumbled on these SDR Dongles. They got me back into the hobby and I joined the GQRP Club. I noticed that almost no one in the QRP fraternity was talking about RTL SDR hence I started writing the Primer  and submitted it to George in late 2014 for publication in Sprat. As you know it appeared in the Spring Sprat and seems to have generated lots and lots of interest in the QRP community. I am delighted by this response and look forward to lots more interesting articles and podcasts. Have fun with your dongle.

Ken G4IIB

PS I wrote another article on getting these dongles to work under Linux. Linux uses completely different architecture so that the software used is completely different to windows. I notice that the software I use for Linux is also available on Mac OS which uses similar architecture (UNIX) so in theory it should also work on a Mac. Quite a few people have expressed an interest in getting a dongle to work on a Mac. As I do not poses a Mac I have not tried this out.

Funcube Dashboard

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