Podcasting since 2005! Listen to Latest SolderSmoke
Monday, September 27, 2021
Lighthouse Larry's GE Sideband Handbook
Monday, September 13, 2021
So Where DID the LSB/USB Convention Come From?
-- Bottom line: I still don't know why ham radio adopted as a convention LSB below 10 MHz and USB above 10 MHz. There are several theories. but so far there is no convincing explanation in favor of any one of them. And almost all of the people involved are probably Silent Keys by now; this makes it more difficult to gather first-hand information.
-- I'm not even sure when the convention began to be observed in ham radio. Many of the early SSB books and articles make no mention of it. We don't see it in early ARRL Handbooks. The first mention of it that I found was in the 1965 issue of the ARRL's "Single Sideband for the Radio Amateur" page 8. This article claims that adding a provision for selectable sidebands would "add appreciably to the cost of the equipment. " It went on to say that, "For this and other reasons there has been a species of standardization on the particular sideband used in the various amateur bands. Nearly all operations in the 3.5 and 7 Mc. phone sub-allocation is on lower sideband, while the upper sideband is used on 14, 21, and 28 Mc."
-- We know that the informal convention was being followed as early as 1958. Jim N2EY reports that in 1958, the manual for the Central Electronics 20A shows that LSB was the "sideband most commonly used" on 75, with USB preferred on 20:
-- There is a widely held belief that this practice originated in the design of a rig that had a 5.2 MHz VFO and a 9 MHz filter. According to this theory such a rig -- due to sideband inversion -- would produce LSB on 75 meters and USB on 20. But, as we have demonstrated, this doesn't work, so this theory has to be discounted.
-- Early SSB activity seems to have been concentrated on 75 meters, and there was a competition for space with AM stations. SSB operators appear to have used the very upper band edge as their gathering spot. Using LSB allowed them to operate very close to the upper band edge -- a lot closer than AM stations could go. This may explain why LSB became the preferred SSB mode on 75. But how do we explain USB on 20 and above? That remains a mystery.
-- It is important to remember that in the early days of SSB, for most hams there were only two important phone bands: 75 meters and 20 meters. 40 meters was CW only until 1952, and even after that was crowded with shortwave broadcast stations. So a design that allowed for both 75 and 20 was twice as good as a monoband design.
-- Early on there were designs and parts for phasing rigs. You could take that ARC-5 VFO at 5 MHz, build a phasing generator around it, and then mix it with a 9 MHz to get on either band. But with just a simple switch, this kind of rig could operate on USB or LSB on either band. So the early popularity of this kid of rig does not explain the convention.
-- There were a lot of surplus 5 MHz ARC-5 VFOs available. There were also FT-243 and FT-241 surplus crystals at both 5 MHz and 9 MHz that could be made into filters. Later in the 1950s, 9 MHz commercial crystal filters became available. If you used a 9 MHz filter with a 5 MHz VFO, there would be no sideband inversion in your rig. If the SSB generator was putting out LSB on 9 MHz, you'd be on LSB on both bands. So if there was a desire to have LSB on 75, why not just also have LSB on 20?
-- But if you built a 5.2 MHz filter and a 9 MHz VFO, you could have LSB on 75 and USB on 20 without having to shift the carrier oscillator frequency. This would save you the trouble and expense of moving the carrier oscillator/BFO to the other side of the passband. This desire to economize and simplify may explain why we ended up with LSB on 75 and USB on 20. But this still begs the question: Why the desire for USB on 20?
-- Both the manufacturers and the hams wanted there to be sideband standardization. With monoband rigs, the manufacturers would be able to cut costs by building for only one sideband. Hams also wanted to cut costs, and they did not want to have to figure out which sideband a station was on when trying to tune him in.
-- By 1962-1963 Swan and Heathkit were selling mono-band SSB transceivers that used the "conventional" sidebands: The rigs for 75 and 40 meters were on LSB while the 20 meter rigs were on USB. There were no provisions for switching to the other sideband. This seems to have reinforced the practice of observing the convention. (Heath later added sideband switching to the HW monobanders -- in view of the growing observation of the convention, they may have been better off sticking with their original design. Does anyone know why they did this?) But again, why USB on 20 and above?
-- In 1963, Swan, by then in Oceanside California, came out with the Swan 240. Swan used a filter centered at 5174.5 kc. The VFO ran from 8953 kc to 9193 kc on 75 and 20. The VFO ran from 12222 to 12493 on 40. This gave the buyer 75 and 40 on LSB, and 20 USB with only one carrier oscillator frequency. (Swan offered a mod that allowed hams to install an additional, switchable carrier oscillator frequency. I luckily acquired one such modified rig.) But again, there is an explanation for LSB on 75, but why USB on 20 and above?
This is an important part of ham radio history. There should be a clear answer. We need to find it. If anyone has any good info on this, please let me know.
Saturday, September 11, 2021
Visiting the Site of Marconi's Wireless Station at Wellfleet, Massachusetts
We were in Boston and the Cape Cod area this week. We stopped off at the Marconi Wireless site at Wellfleet, Mass.
This is from the National Park Service web site:
Spanning the Ocean
Impacting Lives
January 18, 1903 the first public two-way wireless communication between Europe and America occurred. With elation, communiques from President Theodore Roosevelt and King Edward VII were translated into international Morse code at the South Wellfleet and English stations, respectively, and were broadcast.Ocean-going vessels quickly adopted Marconi apparatus to receive news broadcasts, and soon ship-to-shore transmittals were a major operation. Business and social messages could be sent for fifty cents a word. The South Wellfleet station became the lead North American facility for this function. The station’s effectiveness was limited however, so broadcasts were made between 10 pm and 2 am when atmospheric conditions were best.
This brought little enthusiasm from local residents, who endured the sounds of the crashing spark from the great three-foot rotor supplied with 30,000 watts. The sound of the spark could be heard four miles downwind from the station. Eventually, the novelty of wireless telegraphy waned. However, the need for communication at sea remained high. Effective communication resulted in numerous sea rescues, culminating in the Carpathia’s wireless-aided rescue of over 700 people from the Titanic in 1912.
For fifteen years the South Wellfleet sparkgap transmitter continued in commercial use. Skilled telegraphers sent out messages at the rate of 17 words a minute, and station CC (Cape Cod) served in effect as the first “Voice of America.”
https://www.nps.gov/caco/learn/historyculture/marconi.htm
Friday, September 3, 2021
1BCG -- 1921 Transatlantic Test and the Upcoming 100th Anniversary
On December 11, 2021 the American Radio Relay League, The Radio Club of America and the Antique Wireless Association will recreate these historic transmissions on 160 meters near the same location that was used in 1921, using a replica transmitter constructed by volunteers at the Antique Wireless Association. This special event is your opportunity to relive a historic moment in amateur radio history.
The operating schedule and frequency for the 1BCG Transatlantic Tests Special Event has not been established.
Additional details will be posted here when they are available.
Wednesday, September 1, 2021
SSB History -- The Tucker Tin 2 (and 3) with a 1961 Recording. Hallicrafters FPM-200 Video by W9RAN
Wednesday, August 25, 2021
Video: E. Howard Armstrong and Early Radio
Sunday, August 22, 2021
Joe Galeski's 1960 "IMP" 3 -Tube Filter SSB Transmitter, and the Spirit of SSB Homebrew
Here is another important bit of SSB history. In May 1960, Joe Galeski W4IMP published an article in QST describing his super-simple SSB transmitter. While Tony Vitale's "Cheap and Easy" rig was a phasing design, Joe came up with a filter rig. He built USB filter at 5775 kc. With it, he ran a VXO at around 8525 kc. This put him on 20 meter USB.
Here is the QST article: http://marc.retronik.fr/AmateurRadio/SSB/A_3_tubes_filter_rig_%28SSB%29_%5BQST_1960_5p%5D.pdf
In discussing how to put this rig on other bands, Joe got the sideband inversion question exactly right:
Monday, July 26, 2021
QST Repeatedly Got Sideband Inversion Wrong
It kind of pains me to do this. These articles are from a long time ago, and the author is an esteemed Silent Key, but the myth about the origins of the USB/LSB convention is still out there, and as a homebrewer of SSB gear I feel obligated to point out these examples of the error that that myth is based on.
Last Friday, Pete WB9FLW and I were talking about homebrewing SSB rigs. I recommended a series of QST articles by Doug DeMaw. "Beginner's Bench: The Principles and Building of SSB Gear" started in QST in September 1985. There were at least five parts -- it continued until January 1986. (Links to the series appear below.) I hadn't looked at these articles in years, but when I did, a big mistake jumped right out at me: In the first installment, on page 19, Doug makes the same mistake that he made in his Design Notebook:
"Now comes the conversion section of our SSB generator. We must move (heterodyne) the 9-MHz SSB signal to 3.75-4.0 MHz. Our balanced mixer works just as it does in a receiver. That is, we inject the mixer with two frequencies (9 MHz and 5 MHz) to produce a sum or a difference output frequency (9 - 5 = 4 MHz, or 9 +5 = 14 MHz) If we are to generate 75 meter SSB energy, we must chose the difference frequency. We could build an 20-meter SSB transmitter by selecting the sum of the mixer frequencies. The RF amplifiers and filter (FL2) that follow would then have to be designed for 14-MHz operation. In fact, many early two-band homemade SSB transmitters were built for for 75 and 20 meters in order to use this convenient frequency arrangement. The use of upper sideband on 20 meters and lower sideband on 75 meters may be the result of this frequency arrangement (the sidebands become inverted when switching from the difference to the sum frequency.) "
Those last two sentences are incorrect. They repeat the "Myth," or the "Urban Legend" about the origins of the LSB/USB convention. Contrary to what many hams now believe, with 9 MHz filter and a 5.2 MHz BFO it takes more than just switching from sum frequency to difference frequency to invert one of the sidebands.
There are two conditions needed for sideband inversion to take place:
1) You have to be taking the difference product (DeMaw got that right)
2) The unmodulated (VFO or LO) signal must be larger than the modulated signal. (DeMaw and the ARRL obviously missed that part. Repeatedly.)
This is another way of stating the simple, accurate and useful Hallas Rule: Sideband inversion only occurs when you are subtracting the signal with modulation FROM the signal without modulation.
For DeMaw's claim to be correct, one of the SSB signals going into the balanced mixer would have to invert, and the other would have to not invert. Let's see if that happens: He has the sideband signal being generated at 9 MHz and the VFO running around 5 MHz.
9 - 5 = 4 But we are not subtracting the modulated signal FROM the unmodulated signal. SO NO INVERSION
9 + 5 = 14 We are not subtracting at all. SO NO INVERSION.
Thursday, July 1, 2021
Summer Reading for Homebrewers: Frank Jones and the FMLA by Michael Hopkins AB5L (SK)
I read these stories when they were first coming out and I really liked them. Here are all the FMLA episodes. Don't try to read them all in one sitting. Spread them out. Savor them. Think about the message that Frank was sending us.
All of the FMLA episodes: https://tomfhome.files.wordpress.com/2019/12/frank_and_the_fmla.pdf
--------------------------------------
Related articles, books and links:
Frank's obit: https://www.pressdemocrat.com/article/news/frank-jones/
Frank's book "5 Meter Telephony": https://w5jgv.com/downloads/5-Meter%20Radiotelephony%20by%20Frank%20Jones.pdf
Frank's 1937 Antenna Handbook: http://rfcec.com/RFCEC/Section-3%20-%20Fundamentals%20of%20RF%20Communication-Electronics/23%20-%20RADIO%20ENGINEERING%20DATA/1937%20-%20Jones%20Antenna%20Handbook%20(By%20Frank%20C.%20Jones).pdf
About the author, Michael Hopkins AB5L: https://www.rantechnology.com/index.cfm?key=view_resource&TransKey=615604E8-9DAA-40A3-9E48-4160806D893D&CategoryID=8E884CE4-9CED-4957-872B-5EBDB058D540&Small=1
The World's Largest Heathkit Collection (Video)
Thursday, June 17, 2021
The Stubborn Myth about USB and LSB
It has been repeated so often and for so long that many of us have come to believe it. I myself believed it for a while. Like many myths, it has a ring of truth to it. And it is a simple, convenient explanation for a complex question:
Why do ham single sideband operators use LSB below 10 MHz, but USB above 10 MHz?
Here is the standard (but WRONG) answer:
In the early days of SSB, hams discovered that with a 9 MHz SSB generator and a VFO running around 5.2 MHz, they could easily reach both 75 meters and 20 meters (True). And because of sideband inversion, a 9 MHz LSB signal would emerge from the mixer as an LSB signal (True), while the 20 meter signal would emerge -- because of sideband inversion -- as a USB signal (FALSE!) That sideband inversion for the 20 meter signal explains, they claim, the LSB/USB convention we use to this day.
Why this explanation is wrong:
There is a very simple rule to determine if sideband inversion is taking place: If you are subtracting the signal with the modulation FROM the signal without the modulation (the LO or VFO) you will have sideband inversion. If not, you will NOT have sideband inversion.
So, you just have to ask yourself: For either 20 or 75 are we SUBTRACTNG the Modulated signal (9 MHz) from the unmodulated signal (5.2 MHz)?
For 75 meters we have: 9 MHz - 5.2 MHz = 3.8 MHz NO. We are not subtracting the modulated signal from the unmodulated signal. There will NOT be sideband inversion.
For 20 meters we have 9 MHz + 5.2 MHz = 14.2 MHz. NO. No subtraction here. No sideband inversion.
So it is just arithmetically impossible for there to be the kind of happy, easy, and convenient USB/LSB situation described so persistently by the myth.
---------------------------------
We discussed this several times on the podcast and in the blog:
https://soldersmoke.blogspot.com/2015/05/sideband-inversion.html
https://soldersmoke.blogspot.com/2012/05/usblsb-urban-legend-debunked.html
This myth shows up all over the place:
We see the myth here:
http://n4trb.com/AmateurRadio/Why%20The%20Sideband%20Convention%20-%20formatted.pdf
Here the web site owner warns that this is "highly controversial." Really? Arithmetic?
The myth is very old. Here is a clip from a 1966 issue of "73" magazine:
https://worldradiohistory.com/
Finally, to my disappointment, I found the myth being circulated by the ARRL, in the 2002 ARRL Handbook page 12.3:
Saturday, June 5, 2021
Thursday, June 3, 2021
Remastered! The Secret Life of Radio -- With Updated Comments from Tim Hunkin
Tuesday, March 16, 2021
A REALLY Cheap Receiving Rig
-- Has anyone actually made a diode out of a light bulb in the way described?
-- The antenna coupler on the table leg is not much different from the tuner that I have attached to the wall of my car port.
-- Note that when our hero finishes the receiver, he is able to pick up signals from Mars! FB OM.
Who will be the first to recreate this 1921 receiver?
Monday, March 15, 2021
Aladdin's Lamp == The Vacuum Tube (aka The Thermatron) (Video)
Saturday, March 13, 2021
Making Transistors in 1957
Tuesday, January 26, 2021
SolderSmoke Podcast #228
Of course, no travel.
But vaccines are here so maybe soon we can leave our shacks.
In the meantime:
I’ve been playing chess against AI bots on chess.com.
Netflix recommendation: The Bureau. From France. A review from NPR:
A reading from "Conquering the Electron." Germanium vs. Silicon.
Bill’s Bench:
The KLH Model Twenty-one II.
Acoustical Suspension. First receiver
WITH A PILLOW! Bad speaker? Blown AF amp
finals. Hot heat sink. VBE Multiplier. Desitin.
Tony Fishpool’s recommended LM386 boards. 10 for 11 bucks. Nice. They
work. Pictured in the Amazon ad at the
upper right of the SolderSmoke blog page.
Putting a digital display on the Lafayette HA-600A
Test gear trouble. My
Radio Shack multimeter getting flaky. I
many need something better. Auto
ranging? My beloved Maplin AF generator died – will have to fix. I need that
thing. Probably a bad chip. Good thing they are socketed.
I almost forgot about SKN!
But I remembered and I made one contact with the HT-37 and Drake 2-B.
Pete’s Bench:
Presentation to RSGB on Homebrew.
TenTek Troubleshoot.
Swan 240? Looking
nice.
SDR adventures.
MAILBAG
Bill N8ET sent me some really nice Showa 9 MHz 8 pole
crystal filters.
Kevin AA7YQ Smoke jumper!
Building a hybrid SDR.HDR rig.
Launched blog. FB
Nick M0NTV working on similar HDR/SDR project. Great video.
Grayson KJ7UM Hollow State Design – Launched a new
blog. Very FB!
Thomas K4SWL of SWL Post blog. Kearsarge Mountain Transmission system. And recent events.
Peter VK2EMU Poetry.
CW poetry.
Pete WB9FLW looking at DSB rigs…
Drew N7DA Feels not
like a real ham because he hasn’t built a quad from bamboo. Which type of
landscape bamboo is best for antennas?
Ryan Flowers of MiscDotGeek.Com blog is also watching the
Tally Ho YouTube videos of Leo Sampson. Wants to put a WSPR beacon on the Tally
Ho.
Joe KF5OWY Working
with diode ring mixers, trying to see the mixer action on his ‘scope. 1 and -1!
Jim AB9CN sent a cool idea about how to do a 20/17 Moxon.
Roy GM4VKI – I thanked him for his article in SPRAT about
putting a 2n3904 on the output of an NE602 10P mod. Brilliant.
Roger Hayward Told him that I really liked his Dad’s recent
web site updates.
Farhan – Jokingly cursed me for showing him the Oscillodyne
regen of Hugo Gernsback and Jean Shepherd. “Now I will have to build this!”
Tuesday, January 19, 2021
"The Transistor" 1953 Video from The Bell System
Sunday, January 17, 2021
STOP. LISTEN. Shep on Building a Shortwave Receiver
Monday, January 11, 2021
KLH Model Twenty-One II -- Is My Speaker Dried Out?
A few years back Rogier PA1ZZ very kindly sent me a box of electronics parts. Included was an FM table-top radio with a nice walnut case. Thanks Rogier!
I hadn't looked at the receiver in years, but this week I dusted it off and looked it up on the internet. Turns out that it is kind of famous. It was produced by the KLH company. The K stood for Henry Kloss, one of the giants of Hi-Fi audio gear. Henry appears in the picture below.
I got the receiver working, but it sounds awful. It sounds much better with an external speaker, which is disappointing because the internal speaker was the main attraction of this receiver. It even has a little badge on the front panel trumpeting(!) its "Acoustic Suspension Loudspeaker."
I'm wondering if the problem is in fact the speaker. The cone looks intact, but it seems very dried out. It has been more than 50 years... What do you guys think? Picture above. Any other suggestions on what to do with this thing, or how to make it sound better?
Some KLH history:
https://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm