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Thursday, September 16, 2021

The HBR-13C Receiver and the Poetic License of Homebrewers

I've been hanging out on 17 meters with my homebrew VXO-controlled BITX transceiver.  The antenna is my 75 meter doublet fed with window line through a homebrew tuner made from dead ( I swear) DX-40s and DX-60s. I can tune it up just fine on 17 meters, but I realize I probably have lots of nulls and lobes in the radiation pattern.  Apparently one of the lobes is over my old stomping grounds in Panama.  Almost everyday I talk to either HP9SAM or HP3SS. 

Robby, HP3SS, is using SDR gear now, but he was a real homebrewer back in the day.  Years ago he built an HBR-13C receiver. That's quite an achievement. 

Robby -- formerly VY2SS -- told me that he sold his HBR-13C to none other than Joe Walsh, the rockstar from The Eagles.  FB. 

As I was talking to Robby yesterday, I came across this wonderful web page about the receiver: 


Robby told me that his receiver looked almost exactly like the one on the SPARC site, but he didn't recognize the small box with what looked like a speaker on the chassis.  I told him that my guess was that this was a crystal calibrator in an oven. 

I also told Robby that I feel an affinity with the HBR project, not just because I like homebrew superhets, but also because my call in the UK was M0HBR.  

There are some great quotes in the SPARC pdf: 

The SPARC page led me to the amazing website of Kees K5BCQ: 


Here is Kees's QRZ page: 


Wednesday, September 15, 2021

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A thing of beauty. 

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:

-- Some cite a 1959 ITU recommendation on commercial multiplexed radiotelephony as the reason for the convention.  But I don't think this obscure and long-ago ruling explains the convention.  If this were the case, we'd  see follow-up FCC regulation, and at least some discussion of the ITU recommendation in the amateur radio literature.  But we see none of this.  And, as noted above, by 1958 hams were ALREADY -- on their own -- opting to use LSB on 75 and USB on 20.   The 1965 ARRL SSB book refers not to some hard-and-fast rule, but rather to  "a species of standardization" on LSB and SSB.  That ARRL book said nothing of the 1959 ITU recommendation. 

-- 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.  

Sunday, September 12, 2021

Simple SSB Success in Northern Virginia -- "The Radio Does Not Build Itself...."

Dean KK4DAS and the Vienna Wireless Society (VWS) Builders Group have had some remarkable success with Pete Juliano's Simple SSB design.  Sixteen of the rigs have reached the point where the receivers are fully functional.  Eight more have gone the final (!) stretch and have the full transceivers working.  This week Dean and two other VWS builders met up on 40 meters for the world's first multi-SSSB QSO (see Dean's video in the link below). 


Here's Dean's presentation to the club describing the project and Pete's rig: 


As Pete says, "The radio does not build itself..."   Indeed it doesn't!  The VWS builders made these rigs.   FB! 

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

For Marconi the ‘great thing’ was to transmit wireless signals across the Atlantic. He built stations at Poldhu, England, Glace Bay, Nova Scotia, and South Wellfleet, Massachusetts. At this stage of wireless technology relatively long electromagnetic waves were used as signals. Transmitting great distances, therefore, required great sensitivity of receivers and tremendous power. Originally, huge rings of masts were installed to support the needed antennas. When storms destroyed them, they were replaced by sets of four wooden towers, 210 feet in height. Power requirements were tremendous. Keroseneburning engines produced 2,200 volts. When fed to a Tesla transformer, the voltage was stepped up to 25,000 volts – the energy needed to transmit longwave signals so far. It was from the Glace Bay station that the first successful two-way transatlantic wireless test message was sent on December 17, 1902.
A black and white photo of a man and two women standing in an open area facing a building next to a tall circular array of thin antennas.
The original wireless array.

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.”


Wednesday, September 8, 2021

SST -- QRP On The Beach

Up in a beach house on Cape Cod Bay in Massachusetts, I put the SST on 20 meters using an End-fed Half Wave antenna and QRP-guys tuner.  Conditions were pretty bad, with solar storms causing disturbances in propagation, but I did manage to get picked up by RBN skimmers in Iceland, Germany and Italy (see below).  And I had one nice QRP-QRP contact with DK4AN.

I was having trouble getting out until I used the oar to raise the central portion of the half wave antenna -- that's where the current is. 

Thanks again to Bob KD4EBM for sending me the SST.  

Saturday, September 4, 2021

Cosmic Rays, Bit Flips, and Computer Vulnerability

Here is a very interesting video about a problem that many of us have been blissfully unaware. 

You can see the role played by the solar cycle.  This is the subject of some on-going research by the folks who put out the SpaceWeather.com web site.  They have been flying balloons to measure high altitude cosmic rays: 

I've been meaning to build a cloud chamber for a long time.  I recently discovered that my local 
supermarket sells dry ice... 

Thanks to Dave, K8WPE for alerting us to this video.  

Friday, September 3, 2021

1BCG -- 1921 Transatlantic Test and the Upcoming 100th Anniversary

In December 2021 we will reach the 100th Anniversary of the famous Transatlantic Test that marked the first crossing of the Atlantic by radio amateurs.  The video above provides a really excellent description of the momentous event. A few things struck me: 

-- Even then they struggled with amplifiers that wanted to oscillate. 

-- Armstrong should have gotten more credit for the transmitter design.  After all, it was his regenerative system that gave rise to the kind of oscillators that allowed for CW (vice spark) and that formed the basis of the MOPA transmitter that these fellows used. 

-- The info on the Superhet receiver used by Paul Godley in Scotland was really interesting:  It used   "resistance-coupled amplifiers without transformers," similar to what we have today in Farhan's BITX transceivers. 

-- Wow, Harold Beverage himself! And his antenna was used at the Scotland receiving station. 

-- "It was a miracle that no one got mixed up with the high voltage."  Indeed.  

The Antique Wireless Association has built a replica of the 1921 transmitter.  The video below shows it being tested. 

The 1BCG website announces that: 

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.


Thursday, September 2, 2021

A Public Service Announcement


Only YOU can prevent reverse polarity accidents! 
Thank you Jeff Murray.

Wednesday, September 1, 2021

SSB History -- The Tucker Tin 2 (and 3) with a 1961 Recording. Hallicrafters FPM-200 Video by W9RAN

There is so much important SSB history in this video from Bob Nichols, W9RAN.  I liked all of it,  but the on-the-air recording of a 1961 transmission from a Tucker Tin 3 was really amazing.  Check it out. 

Here is the 2014 SolderSmoke blog post about the Tucker Tin 2. You can see the 1961 schematic here: 

As you can see this is a very simple phasing-type SSB rig.  The SSB generator is crystal controlled at the operating frequency.  

Thanks to Bob W9RAN, and thanks to Peter Parker VK3YE for posting about this video on the SolderSmoke Facebook Page. 


The Chatham Islands

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column