Monthly Archives: October 2020

1940 British One Tube Shortwave Regen

1940OctPracWirelessThe plans for this simple one-tube wartime regenerative receiver appeared in the British Practical Wireless, October 1940. The author reports that nearly any triode can be used, and he suggests that if more than one is available, they should all be tried to find the best specimen.

The author reported that he was able to pull in many DX transmissions that evaded his friends. He attributed this not only to the sensitivity of the receiver, but also to his patience and possibly good location.

The author used an aluminum chassis, which he acknowledged might not be available. He noted that perforated zinc might be substituted, as long as good ground connections could be made.

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One Tube Electronic Keyer, 1950

1950OctRadioNews
Seventy years ago this month, the October 1950 issue of Radio News carried the plans for this one-tube electronic keyer. The accompanying article describes the circuit in detail, but the reason for two relays is interesting.  The circuit uses a 117L7 tube, half as a rectifier, with the pentode section serving as the relay circuit.  The length of the dots and dashes is determined by the time constant (R times C) of the resistors and capacitors near the key.  Their voltage is fed to the grid of the tube, which turns the plate circuit on and off.

One of the critical design features is that the next dot or dash doesn’t begin until the previous one, and the space following, are finished. The second relay serves this function, as it doesn’t close until the dot or dash is completed.

The author of the article and designer of the circuit was Donovan V. Geppert, W5KFP, an Assistant Professor of Electronics at the University of Arkansas.  He was the author of the textbook Basic Electron Tubes, which is available online at this link.



1950 One Tube Broadcast Portable

1950OctPMThis young woman is listening to a broadcast program on a “handi-talkie” style radio from the October 1950 issue of Popular Mechanics. The set is a simple one-tube regenerative receiver, with a high-impedance headphone built right into the side of the set’s wooden case. A lead with an alligator clip is used to connected to an expedient antenna. In this case, she is pulling in a station by using the lamp’s metal case as an antenna. A telephone dial stop could also be used, or outdoors, a railing or gutter.

Power is supplied by a flashlight battery for the filament, and a 30 volt hearing aid battery for the B+.

1950OctPM2



COVID-19 Travel

Custer State Park, SD.

Custer State Park, SD.

One segment of the economy that has boomed due to the pandemic is anything involving the outdoors. Americans have discovered that outdoor activities are a safe source of recreation. One industry that has seen a particular boom is the recreational vehicle industry. According to this recent article, RV sales in July were higher than they had been in 40 years. And campgrounds, whether it is state parks or private campgrounds, have been packed.

This is understandable for a few reasons. First of all, I for one, am not about to get inside a pressurized tube with a bunch of strangers, so it’s unlikely that I’ll be taking any commercial flights any time soon. Similarly, it will probably be a long time before the cruise industry rebounds. So the best choice for long distance travel is driving, and an RV allows one to not worry about the cleanliness of a hotel room.

And there’s another factor at work. Millions of Americans are working remotely, and their kids are attending school remotely. Since they don’t have to show up at work or school on Monday morning, many of them realized that they could go to work and go to school from the road, as long as they had an internet connection. That’s exactly what we did recently. We waited until after school started, and then took a working vacation to Yellowstone. I would have preferred to do it in a $100,000 diesel pusher motorhome, but we don’t happen to have one of those. What we do have is an 8 foot popup towed behind our minivan, and we decided to use that.

Staying Connected on the Road

In campgrounds, we saw quite a few people, adults and children, sitting at picnic

Boost Mobile Coverage Map.

Boost Mobile Coverage Map.

tables with a laptop. So I assume that they, like us, were at work or at school. We stayed mostly at KOA campgrounds, most of which have very good WiFi connections. When we were driving, or in state park campgrounds, we used a cell phone hotspot to connect. While our connections sometimes failed, they were reliable most of the time. There were a few occasions when we had a meeting that we absolutely had to attend at a certain time, and

Verizon Coverage Map.

Verizon Coverage Map.

Cricket Mobile Coverage map.

Cricket Wireless Coverage map.

on those occasions, we did need to plan ahead a bit. Overall, we found that Verizon had the best connections in the Western states we visited. For example, in Yellowstone National Park, Verizon had service available near all of the major centers.  Between the four of us, we had three cellular providers, and Verizon was the most reliable where we were.  My phone, which uses the prepaid provider Boost Mobile, which uses the Sprint network, had absolutely no service for most of the trip.  I looked at their coverage map after the fact, and while they have very good coverage in the eastern half of the country (especially along interstates), they have essentially zero coverage in much of the Intermountain West.  My kids both have service with Cricket Wireless, which uses the AT&T network, and they also had good coverage in most areas.  Verizon seemed a bit more reliable, but there were a couple of occasions when they had service but my wife’s Verizon phone did not.

If your work depends on having internet available, the moral of the story is that you should plan ahead.  Between our three providers, we had very reliable service.  But occasionally,  the best provider was unavailable, but another one was available.  One workaround to increase your reliability if you have only one provider would be to buy a cheap prepaid phone from another providers.  If both your primary carrier and that carrier have reasonably good service in the area where you plan to travel, you’ll increase your chances of having a good connection from any given spot.  Phones are available for about $60 or less, and a month’s service is generally about $30.  The inexpensive plan might run out of data, but you can generally buy more.  Having a second cell phone with a different provider could be good insurance if you need coverage.  You can turn either phone into a hotspot and use that for your other devices.

Prior to the trip, we did buy a dedicated hotspot with Verizon service, but it didn’t seem to provide any better service than the Verizon cell phone.  And unfortunately, the hardware stopped working during the trip, and will have to be returned.  Frankly, I don’t think there was any advantage over simply using a cell phone as a hotspot.

Inside Yellowstone Park, there was cellular coverage near all of the major destinations, such as Old Faithful, Fishing Bridge, Mammoth Hot Springs, etc.  On one occasion, we were touring the park when my wife had a Zoom meeting to attend.  We stopped at Fishing Bridge, where she had a good signal, and she worked in the car while the kids and I viewed the sites.  However, when we strayed even a few miles from one of these sites, there was no service. Our base of operations during our stay at the park, the West Yellowstone KOA, had very good WiFi.  So we generally attended school and work from the campground in the morning, and then toured the park without regard to connectivity.

There were a few times when the kids simply missed a class because an internet connection was unavailable.  So you need to be flexible, and if you have an important meeting you need to attend, you need to plan to be in a place with a solid connection.

Social Distancing on the Road

Family dinner at Mammoth Hot Springs, Yellowstone, of buffalo burgers purchased at food truck outside the park.

Family dinner at Mammoth Hot Springs, Yellowstone, of buffalo burgers purchased at food truck outside the park.

We are being very careful with social distancing, and the trip had few challenges. We recognized beforehand that there would be some situations where we would have to go inside buildings to interact with others, although we kept those situations to a bare minimum. When we did need to go inside and/or interact closely with others, we wore KN95 masks, which provide some protection to the person wearing them. I’d feel better if I had an N95 mask that was made in the USA, but those aren’t available yet. Camping does not always allow the opportunity to wash your hands thoroughly with hot water, so we also brought along and used plenty of hand sanitizer. In addition to the N95 masks, we always had with us either a cloth mask or a disposable surgical mask.

I would say that about half of the people we saw were wearing masks when it was appropriate to do so.  Buildings inside the national park required masks, and most were honoring that requirement.  A few people had what appeared to be N95 or KN95 masks. Most had simpler cloth face coverings.

For the most part, other people we encountered respected our social distance. In campgrounds, when we talked to other campers, they instinctively kept their distance. We did have to keep up our guard, however, since others would sometimes decide to intrude upon our personal space. For example, at Old Faithful, my daughter and I were holding a spot at a bench for the rest of the family when an unmasked woman simply came to our bench and sat down a couple of feet away from my daughter. There was little we could do other than move as far away as possible from her, tighten our masks, and try to breathe in the other direction.

At Mount Rushmore, I was sitting minding my own business when an elderly woman, in an apparent effort to impress her granddaughter, started hopscotching toward me. I held my breath, quickly got up, and found another place to sit.

Buying Supplies on the Road

Cody, WY, Walmart. Google Streetview.

Cody, WY, Walmart. Google Streetview.

Without exception, when we bought gas, we paid at the pump and didn’t have to go into the store.  Since the process did require handling the pump and entering a zip code on the display, I made a habit of slathering my hands with hand sanitizer when done.

For an almost two week trip, we did have to buy groceries. To avoid having to go into the store, we placed an online order at Walmart, and picked up our order at the Walmart in Cody, Wyoming. In most cases, it’s necessary to place an order about two days in advance, so this requires some advance planning. But we placed the order from a cell phone while driving, and later added some items we thought of.

One good resource for buying things on the road without direct contact is Walgreens. The Walgreens website allows you to order a limited selection of items, and pick those up at the drive-thru window. In one case, we needed a charging cable for an iPad, which wasn’t listed on the website. But when we called the store, they were happy to leave it at the drive-thru, and we were able to pick it up a few minutes later.  For staples like bread and milk, you can place your order online, and then pick it up and pay at the window.

Most (but not all) major supermarket chains have online ordering for in-store pickup. In many cases, the service is through InstaCart, and their website will show available stores in the area where you are travelling. Walmart’s ordering is done directly through their website, and as far as I know, all Walmart stores offer curbside pickup.

Sanitation Resources

As the song goes, “it’s a problem to be faced, what to do with human waste.” This is one great advantage of traveling in a larger RV with its own toilet. In our case, we have a small portable toilet in the camper, like the one shown here, which is really best for emergency situations. And it also needs to be emptied by going into the bathroom.

In some cases, the only option was a public restroom, which meant using the KN95 mask. After using the bathroom, I washed my hands thoroughly, but I usually had to touch the doorknob before leaving. So my routine was to stop outside the restroom, apply hand sanitizer, and then remove my mask.

One advantage of state and national parks is that they often have what are euphemistically called “vault” toilets, or pit toilets. To the squeamish, these might seem to be less than ideal. But in general, they are kept clean. And they have the great advantage of providing automatic social distancing. You are isolated from everyone else, so there’s no chance of breathing in a virus exhaled by the person in the next stall. In general, if I had the choice between a “vault” toilet and a “modern” restroom, I opted for the vault, since I believe it is safer. At one of our campgrounds, the campground had a “modern” restroom, but there was a picnic area about a mile away with a rarely used vault toilet.  I made the short drive to take advantage of the added safety.  I also took advantage of the vault toilets to empty our portable toilet, a job that for some reason always devolves upon me.

In many cases, such as state parks, a vault toilet is available in the campground.  So even if you’re not camped there, a drive into the campground will allow you to find this facility.

Many locations, such as Mt. Rushmore, had a bank of portable toilets set up, even though the modern restrooms were in operation.  Again, even though it sounds counterintuitive, it seems to me that the portable toilet, where you are isolated, is safer than a public restroom.  I did notice that this toilet was out of hand sanitizer, so you do want to carry a small container with you at all times.  I kept mine stored in a fanny pack, along with my KN95 mask, stored in its own paper bag.  (Here is CDC guidance on re-use of “disposable” masks.)

To avoid public showers, we did have a solar shower and shower tent which we used a couple of times.  The shower is designed to be hung from a tree, although we found that the most convenient option was usually to put it on the roof of the car.  (For more information about solar showers, see my earlier post.)  It did prove to be an inexpensive and convenient option.

One thing that I noticed, particularly in Yellowstone National Park, was the huge number of rental RVs. We must have seen hundreds of motorhomes with a prominent ad for CruiseAmerica.com. They aren’t exactly cheap, but the cost is comparable to a hotel room. If one doesn’t own an RV and wants to travel, this seems like a viable option.

I’ve never been to Yellowstone National Park in the fall, but it did seem to be quite crowded for the off season. The crowds weren’t an issue, but I believe they were higher than usual, since others probably had the same idea we did. For most of the nights of our stay, we did have campground reservations, and most of the campgrounds where we stayed appeared to be full or almost full.

My experience with the Minnesota State Parks is that if you want to go camping, you’ll find many options available during the week. If you’re flexible, you’ll find many interesting places to camp. On weekends, there are fewer options. Previous years, I’ve almost always been able to find a weekend camping spot on very short notice. This year, that might not be possible on a weekend, but it still is on a weekday. I suspect other states are the same. The campground host at Custer State Park in South Dakota said that this year, the campground is full almost every night, whereas in previous years, there were often spots available.

Every segment of the industry seems to be at its limits.  We had recently purchased a new vehicle and had to have a hitch installed.  The dealer who installed it (Bauer’s Custom Hitches in Minnetonka, MN, which did an excellent job) was unable to get the hitch from their normal supplier.  I eventually found one at O’Reilly Auto Parts, which had the right hitch in stock locally.  The dealer was so surprised that I found one that they bought them retail for the other customers who were waiting for the same part.

We were gone for about 12 days, and traveled from Minnesota first through North Dakota and Montana to Yellowstone, and then back through Wyoming in South Dakota. In retrospect, we should have stayed put at some of those sites a few more days, rather than driving so much. Since we can, we’ll probably take more similar trips this year, but probably put in fewer miles. The $100,000 diesel pusher would probably provide more convenient options for four of us to be working or going to school. But since we don’t have one of those, the 8 foot popup seems to work almost as well.



Navy Navigation System, 1920

WashHerald100720This wire service article is dated a hundred years ago today, October 6, 1920. Although the headline says “radio,” it appears that the system actually used an AF signal. The cable lying in the channel was the primary of a large transformer, and the coil in the ship was the secondary.

RADIO GUIDES ‘BLINDED’ SHIP FIFTEEN MILES

Dots and Dashes of New Invention Thwart Ambrose Channel Perils.

FIRST TEST AMAZING

Navy Proves Value of Device Young Californian Has Developed.

(By Universal Service.)

New York, Oct. 6.

With the glass front of the bridge completely covered with heavy canvas, rendering him blind to all intents and purposes, Commander H. H. Norton, U. S. N., this afternoon piloted the I destroyer Semmes through the narrow, devious ways of Ambrose Channel from the Ambrose light to Fort Lafayette, a distance of 15 miles.

The only thing he had to guide him was the monotonous click of a few dots and dashes repeating over and over again, a million times, the one word, n-a-v-y. But as long as he heard it, he knew I he was on the-right course.

If the sound grew slightly faint, he would turn a little lever right and left which accentuated or diminished the sound. That would show him that he was going either to the right or left of the center of the channel. Then he would turn the ship’s nose in the proper direction again.

Past the dangerous bend in the channel just off Roamer shoals, where many a pilot has met disaster, Commander Norton guided the Semmes as straight as a die along the center of the ships’ roadbed. Then, approaching Fort Lefayette, with hundreds of ships of all descriptions on every side he continued triumphantly on his sightless way.

Pilot System’s Flrst Test.

The occasion was the first test by the government of the radio piloting cable system, the invention of Earl C. Hanson. 28 years old, of Los Angeles. The test was arranged by Comdr. R. F. McDonnell, in charge of the government’s radio system
and was witnessed by a score of other naval officers, expert electricians and engineers.

During the war there was much comment as to just how the warships were able to move through the mine infested waters. Just recently it has become known that they operated by a system of audio frequency sound waves. Young Hanson, who is connected with the Navy Department, decided that the idea could be made practical for guiding ships through narrow channels when fog rendered them useless and tied up all shipping. The Navy Department thought so well of the idea that a year ago it took over Hanson’s idea to complete its development.

For months past they have been busy laving an insulated electric cable along the entire length of Ambrose Channel. It required 87,000 feet of cable. One terminal of the generator producing the alternating current is connected at the shore and to a ground current. The other terminal is grounded at the bottom of the channel. Although the cable is fully insulated, it is a fundamental law of electricity that any conductor carrying an electric current produces a magnetic field around the conductor.

Copper wire on Board.

Aboard the Semmes (the only ship yet equipped to use the new invention) are two coils of copper wire on the bow.

These coils pick up the electric current and transmit it to a small set of amplifiers. Attached to these is an ordinary set of telephone receivers. From the shore end at Fort Hamilton is an automatic device which spells out “Navy.’

When a ship reaches the mouth of the harbor it picks up the sound within a thousand feet on either side of the actual location of the cable. Then, if the fog be so thick that the pilot cannot see ten feet on either side of him, he follows the sound, which gets louder and louder as he approaches. When he is astride the cable, all he has to do is to follow it, as simply as a blind man would follow a string stretched along the length of Broadway. Commander McConnell declared yesterday that if the system had been in operation during the dense fog which held up hundreds of ships outside the harbor last week, every one of them would have made their docks without an hour’s delay.

This clipping is from the Washington Herald, October 7, 1920.



Eclipse of June 10, 2021

The photo above was taken in Bavaria at sunrise during the eclipse of May 31, 2003.  That was an annular eclipse, meaning that the sun is never entirely obscured by the sun.  Because the moon is slightly too far away, there remains a ring of sunlight.  It’s essentially the same as a partial eclipse, in that the world does not get appreciably darker.  It’s an interesting phenomenon, but not particularly amazing.  In most places, if nobody told you it was in progress, you might not even notice.  For example, I drove to Springfield, IL, to see the annular eclipse of May 10, 1994.  It was somewhat interesting, but there really wasn’t much to see.

There are two exceptions however, one of which is shown in the photo.  At sunrise and sunset, the disc of the sun is visible.  So if the annular eclipse (or a partial eclipse) is happening at sunrise or sunset, it will be quite apparent.

Path of June 10, 2021, eclipse. NASA image.

Path of June 10, 2021, eclipse. NASA image.

There will be an annular eclipse in North America on June 10, 2021.  It’s drawn little attention, since most of the path of annularity will be over unpopulated areas in Northern Canada, Greenland, and Siberia.  Much of the Canadian path is over Hudson Bay and James Bay.  So unless you’re one of the few thousand Canadians living in the path, the event will be of little interest.

However, the one exception where the eclipse is visible over inhabited areas is also the one place where the phenomenon will be most interesting:  The partial or annular eclipse will be visible at sunrise in Northwestern Ontario, near the city of Thunder Bay.  In Thunder Bay, the sun will be about 70% covered by the moon at sunrise, and the sunrise should clearly show the partially eclipsed sun.  Just a few miles northeast of Thunder Bay, there will be an annular eclipse at or near sunrise, which should result in a view similar to the one shown above.

I have two viewing locations in mind.  I’ve already made a hotel reservation in Longlac, Greenstone, Ontario, which is 305 km from Thunder Bay along the Trans-Canada highway.  The lawn in front of the hotel seems to have a good view of the sunrise.  From my home in Minnesota, it’s about a 9 hour drive.  That’s actually my backup plan, since I was already able to make a refundable hotel reservation.  My primary viewing location is Macleod Provincial Park, where the campground is next to a lake, which seems to have a good view of the sunrise.  Camping reservations, however, are only available five months in advance.  So in January, I plan to make reservations, and after they are secured, I’ll cancel the hotel in Longlac (and I’m sure it will get snatched up quickly, since it’s one of the few hotels in the path of annulaity.)

It should be a spectacular view, but there are two possible problems.  The first is the possibility of cloud cover, since there appears to be cloud cover about 60% of the time in this part of Ontario.  As we did in 2017, we’ll just have to hope for the best, and perhaps plan to drive a few miles to a break in the clouds.

The other potential problem, of course, is COVID-19.  Since March, the U.S.-Canadian border has been closed to non-essential travel, and this trip is clearly non-essential.  Again, I’ll have to hope for the best.  If the border remains closed, there will be about 16% coverage of the sun at sunrise at home in the Twin Cities.  So it won’t be particularly spectacular, but it will be worth getting up to view.

But as one heads northeast, the coverage gets greater. For example, in Duluth, MN, there will be about 40% coverage of the sun as the sun rises over Lake Superior. Just south of the border at Grand Portage, the coverage will be about 70%.  Anywhere along the North Shore of Lake Superior between these two points, the view should be spectacular as the sun rises over the lake.  So if the border is still closed, that’s probably where I will be.

Other cities in North America will experience a spectacular sunrise that morning. In Toronto, for example, the coverage will be about 72%. Philadelphia, New York, and Boston will all have coverage of more than 70%. Winnipeg will have about 40% coverage at sunrise, and much of Saskatchewan will have at least some coverage at sunrise. Further west, Fairbanks, Alaska, is the only other North American city with anything to see, with about 24% coverage at sunrise.

 

 



1940 Three Tube Broadcast Receiver

1940OctPS1940OctPS2This gentleman is pulling in a program on a three-tube set he built for only $4.06, following a design from the October 1940 issue of Popular Science.

The chassis for the set was an aluminum cake pan. The article noted that this had the advantage of being able to be cut with a normal pair of scissors. The handsome cabinet was made from scraps of wood from the author’s workshop. The coils for the regenerative set were made “honeycomb” style on cardboard forms. The set covered the broadcast band, but the author noted that by tweaking the size of the coils, it would be possible to pick up stations slightly above and below the standard broadcast range.1940OctPScoils

The efficient circuit provided loudspeaker volume, driving a PM speaker.

1940OctPSschematic



GE Model JB-410 Portable, 1940

1940OctRadioTodayThis young woman is pulling in a program on her new personal portable radio, the GE model JB-410.  The set weighed in at just 4-1/2 pounds and sold for $19.95. The photo appeared eighty years ago this month in the October 1940 issue of Radio Today.

The superheterodyne set featured a tube lineup of 1R5, 1T4, 1S5, and 1S4, and ran from a 67.5 volt B battery and two 1.5 volt A batteries. There is an example of the set in the collections of the Smithsonian.  There is no photograph available, but presumably if enough people click on the link and then click the button to request a photo, the museum staff will oblige.



Miss America’s Portable Radio: 1940

1940OctRadioRetailingShown here is Frances Marie Burke (later, Kenney), Miss America 1940,  tuning in a program from Atlantic City on her portable radio.  The photo appeared in the October 1940 issue of Radio Retailing, which didn’t identify the brand of radio, but reminded that beach portables would be popular the following summer.



October 1, 1940 Eclipse

1940Oct1WashEveStarToday marks the 80th anniversary of the total solar eclipse of October 1, 1940, which was visible in Colombia, Brazil, Venezuela, and South Africa.

One focus of research for this eclipse was its effect upon the ionosphere and radio propagation. As shown from the clipping above (Washington Evening Star, Oct. 1, 1940), scientific teams from the National Geographic Society and Brown University had travelled to Patos, Brazil, and had photographic equipment at the ready. Unfortunately, however, a thick layer of clouds prevented visual study. Other experiments, however, focused on radio propagation and were presumably unaffected by the clouds.

In preparation for the radio studies, the National Bureau of Standards had previously published data regarding normal ionospheric conditions on the date of the eclipse.