Sibeband Inversion: 9 MHz, 5 MHz, and the ARRL Handbook

The 2006 ARRL Handbook had it right.  Jeremiah went back and took a look: 


Bill:

I have a comment about the question of the LSB/USB convention mentioned in the most recent SolderSmoke podcast and the follow up blog post:

I checked the 2006 Handbook and there is a sidebar (page 9.27) explaining the 5/9 MHz connection with the Lower/Upper Sideband convention in use today. It explains that there was a popular rig that used a 5 MHz VFO and a 9 MHZ IF that were mixed to create the 75/20 meter RF signals. This is certainly a reasonable method, but would not result in the inversion. The article then goes on to explain, however, that other rigs used a 5 MHz tunable IF and a 9 MHz local oscillator which would indeed result in sideband inversion and thus the convention we use today. 

73,

Jeremiah, KB0OFF

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GE Ham News -- All of Them! (1946-1963)

Walter, AJ4UM, alerted us to this. Here's yet another treasure trove of ham radio literature.  I'm going to have to retire just to make time to read all the stuff that is coming on line! 
http://n4trb.com/AmateurRadio/GE_HamNews/ge_ham_news.htm


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EDN Article on Performance of Modern Ham Transceivers

Mike, KC7IT, alerted us to a very interesting EDN article about the performance of modern ham transceivers:
http://www.edn.com/article/521690-High_performance_HF_transceiver_design_A_ham_s_perspective.php?cid=Newsletter+-+EDN+Fun+Friday


On the phase noise, how do old fashioned LC or crystal oscillators compare to modern PLL or DDS circuits?


And congrats to Elecraft for the high ratings on their K3.



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In the Shadow of Giants (at Tektronix)

From: Dave Haupt
Subject: Club 465
To: n2cqr
Date: Monday, May 7, 2012, 1:40 PM

I work at Tektronix, in a group that designs, among other things, front-ends for our spectrum analyzers.  In our lab full of gear, the most coveted scopes are the 465, the higher frequency 475 and the ultimate manifestation of the breed, the 2465 (four 350MHz channels).  Yes, we have the more recent higher-frequency digitizing scopes in the lab, and for much of what we develop, we need the higher frequency and superior triggering capability.  But for ease of use, confidence that what's on the screen is the real signal and not some processor's guess, those of us with more gray in our hair than any other color still have warm and fuzzy feelings toward a good analog scope.

What REALLY makes me stand still in my tracks is when I comment to someone at work that I have a 465 at home, and they reply, "Oh, yeah, I remember that design.  I did the horizontal sweep circuit."  Talk about standing in the shadows of history!

Dave W8NF

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Evil Mad Scientist Builds a Heathkit

You guys will get a kick out of this:  An old unbuilt Heathkit is discovered, and is then put together by "Evil Mad Scientist." EMS obviously loves electronics, but is clearly of the digital/IC generation:    "The tubes are gorgeous!  Their exteriors are glass with electrodes extending from the bottom!"  Wow.

The Evil Mad Sci guy fears that the solder provided by Heath will have "gone bad over time" and says that he will use "more modern solder."  Hold your horses Frankenstein! Don't you dare put that Heathkit together with lead-free solder!  That could tear a hole in the fabric of space time!  Also, I dunno about the idea of putting all the components on the lugs and rotary switch terminals first, with all the soldering coming later.  The boys at Benton Harbor wouldn't have liked that.  And you might want to gradually bring the voltage up on that big electrolytic cap up using a variac.  Which brings to mind some needed advice:  BE CAREFUL!  You have moved out of the realm of 12 V DC.  That old Heathkit could zap you good! 

http://www.evilmadscientist.com/article.php/heathkit-part1


Thanks to Mike Butts for alerting us to this.

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USB/LSB Urban Legend DEBUNKED!

Astute aficionados (like Steve --Snort Rosin -- Smith) immediately recognized that I was talking rubbish when, in SolderSmoke 143, I said that the current LSB/USB convention on the HF bands has its origins in the FACT (not!) that when using a 9 MHz filter and a 5 MHz VFO, with a single carrier oscillator crystal you can very conveniently get USB on 20 and LSB on 75, supposedly because of "sideband inversion" that takes place when you switch from the sum product of the second mixer (20 meters) to the difference product (75 meters).  I got out paper and pen and quickly discovered that Steve was right.  No sideband inversion with this scheme.

I was susceptible to this urban legend because when I was building my 17 meter SSB rig out in the Azores,  I used a 5.174 MHz filter from an old Swan 240.  I started out with a VXO running around 12.9 MHz, obviously using the sum output from that second mixer.  Later, I decided to move the VXO up to around 23.3 MHz and take the difference product.  Here I DID get a sideband inversion, and I had to go back to the carrier oscillator and change the crystal so as to get LSB coming out of the filter.  When this 5.173 MHz LSB went to the second mixer, the sideband inversion took place and --Viola!-- 17 meter USB resulted. 


The key factor here of course is that the VFO freq was now ABOVE the filter freq.  


In the podcast I said that I "learned" about the alleged origins of the LSB/USB convention from the 2006 ARRL handbook.   I had read it very quickly while in the local library.  I don't think they would have gotten this wrong.  It was probably my quick reading of the article that caused the rubbish talk.  


Maybe it was this:   Could it have been that in the early days of SSB, guys were using a 5 MHz FILTER with 9MHz VFOs?  Maybe from old Command Set surplus gear?  With the VFO above the filter freq you would get the sideband inversion that I was babbling about, right?   Or might this have been the result of the phasing method of sideband generation popular back in the day?   
 

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SolderSmoke Podcast #143

SolderSmoke Podcast #143 is available:


http://soldersmoke.com/soldersmoke143.mp3


Cappuccio the Flying Retriever
Kite Flying (no  injuries this time!)
April 1 getting more and more difficult
Turtle Wax and Telescope Maintenance
Titan's Orbital period
NJQRP's Amazing "Chat with the Designers"
QRP-Tech and A-QRP
Billy's workbench and computer build
Sony Vaios goes toes up (really)
Digi modes make me grumpy
Kick Panel rig gets a receiver
The Joy of Belden 1671A
I want to bulild a BITX 75/20!
Solar Flux when I was born (300+)
SPRAT 150! Congrats!
Jason NT7S and his new OpenBeacon QRSS kit
BONANZA!
MAILBAG


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Hans Summer's Homebrew 'Scope

  

The picture right away gives you a sense of the depth of this project, and of the guy who completed it.  One of my biggest mistakes in the UK was missing the opportunity to meet Han Summers, G0UPL.  Check out Han's Homebrew 'scope project, and be sure to look around his site for other, similar adventures:


http://www.hanssummers.com/tinyscope.html

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Alan Sends Video Through HIs 'Scope

Who needs plasma screens!  Real hams get their video on the screens of Tektronix oscilloscopes! 

Good one Alan!  Glad to see that you made it onto Hack-a-Day with this one! 

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Kick Panel Progress; Podcast Delay

 

I'm kind of behind on podcast production, but once again I have a good excuse:  I've been melting solder.   I decided to finally finish the Kick Panel DSB rig that I started building back in London.  It is built on a kitchen cutting board purchased in a Dyas store in Windsor.  The cabinet is fashioned from an aluminum kick panel for a door (a pub door!).   

I originally intended this to be just a transmitter (for use with my trusty Drake 2-B) but it is so easy to add a direct conversion receiver to a DSB rig that I just threw together a version of the NE-602 LM386 Neophyte receiver and hooked it up to the 75 meter VFO.  It sounds great.  I love DC receivers. They seem to connect you directly to the ether. And now I'll have a complete 75 meter DSB station in one box.

This morning I tested the balanced modulator (singly balanced with two diodes).  DSB is being generated.  All I have to do now is put a little 6 db pad between the modulator and the amplifier chain, then work on the antenna a bit and I should be on 75.  The amplifier chain dates back to the period when Mike, KL7R, and I were using LTSpice to design amps....

I was very pleased to include in this rig a part that Michael, AA1TJ, sent me:  I have a little 10.7 MHz IF can in the front end of the RX.  A cap allows it to tune in 75 meters. Thanks Mike!

I hope to get a podcast out this weekend (if the computers cooperate -- the Sony Vaios "light bulb-repaired" laptop finally gave up the ghost last weekend.) 

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SolderSmoke Lexicographer

Mike, AA1TJ, is the QRPoet Laureate, but I think we can now officially name Steve Silverman, KB3SII, our official SolderLexicographer:

Hi Bill

Here is an interesting possible explanation for the term LID:

'It's a term that goes back to land based telegraphers, before radio was even used. Some say it has to do with placement of a tobacco can or lid to enhance hearing the telegraph sounder. Such things were apparently trademarks of the poorer ops.'

So there you, using a tobacco can sounder "hearing aid" defined you as a LID, as in using the lid of the can to tune your RIT.  But in telegraph location with lots of QRM, such as in a major telegraph office or along side of a noisy train track, the lids enabled an operator to distinguish his sounder from the background clicks and clacks.  The Car Talk guys would love this explanation.

73

Steve

KB3SII





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The Idea Factory

Hello Bill,

I think you will like a new tech history book about Bell Labs. The name of the book is The Idea Factory and the author is Jon Gertner.

Here's a neat example of what's in the book from page 85:

"Atoms within semiconductors bond easily with a number of other elements. Scaff and his colleagues knew that when they cut n-type silicon (atomic number 14) into smaller pieces on a power saw, for instance, they could smell something they were sure was phosphorus (atomic number 15). None of the measurement equipment could pick up the taint, but their noses could."

How cool is that? The book is full of this kinda of stuff and it details the early lives of those involved in Bell Labs.....anyway I find Idea Factory a page turner and I think you will enjoy it.

Another "abstract" from page 38:

"The young Bell Labs recruits had other things in common. Almost all had grown up with a peculiar desire to know more about the stars or the telephone lines or (most often) the radio, especially their makeshift wireless sets. Almost all of them had put one together themselves, and in turn had discovered how sound could be pulled from the air."

73

Herb/WR9H

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