Monthly Archives: January 2016

Stewart-Warner Concert Grand Radio-Phono, 1941


Seventy-five years ago today, this high-quality radio-phono was under a hundred dollars (with trade in of your old radio), at Gimbles Department Store in Milwaukee. This add appeared in the January 31, 1941, edition of the Milwaukee Sentinel.

The set came in a deluxe mahogany cabinet, and featured world-wide reception (presumably meaning that it tuned both standard broadcast and shortwave).  The automatic record changer would accomodate up to fourteen records.  It also had a “built-in antenna and ground.”

Ice Age National Scientific Reserve: ARRL National Parks On The Air

The Ice Age Trail Marker at Interstate State Park.

The Ice Age Trail Marker at Interstate State Park.

Today, my kids (shown in the photos) and I did a little bit more exploration of a nearby unit of the National Park Service, for the ARRL National Parks On The Air (NPOTA) event.  There aren’t many actual National Parks within driving distance of the Twin Cities, but there are a number of units that are part of, or affiliated with, the National Park Service.

Another “National Park” Close to Home

I was suprised to learn that one of them was Interstate State Park in Wisconsin, which is one of nine Wisconsin parks included in something called the Ice Age National Scientific Reserve,  an affiliated unit of the National Park Service (NPS).  Therefore, an activation from this park “counts” for NPOTA, and today, I went to check out the possibilities.  The kids had the day off from school and it gave them a chance to get outside.


Glacial Pothole at Interstate State Park. National Park Service photo.

The “Ice Age” nomenclature for Interstate State Park is very fitting, because the landscape was carved out by the glaciers.  The portion of the trail we were on today is called Pothole Trail, since it is the site of massive potholes carved into the rock by the combined action of glaciers and the rushing water as they receded.  Over the eons, boulders got captured by whirlpools, where they ground deep potholes into the solid rock.  Because of the snow cover, we didn’t see any today, but there are many examples just across the river in the eponymous Interstate State Park in Minnesota.

Good News for Parents of Fourth Graders

But more importantly, I had a selfish motive for bringing the kids along.  One of my kids is in fourth grade.  Under the National Parks Service Every Kid in a Park program, every fourth grader in the nation is entitled to a free pass to all national parks and other federal sites until August 31.  They can bring with them an unlimited number of children, and up to three adults.  Since Interstate Park has a connection with the National Parks Service, this means that I get in free, as long as I bring my daughter.

This represents a huge savings in money.  The National Parks Service normally charges about $80 for an equivalent pass.  And an annual non-resident vehicle sticker for the Wisconsin State Parks is normally $38.  So the fortuitous circumstance of having a fourth grader in the household will represent a big savings.  We buy a Minnesota State Park sticker every year, but don’t usually buy the $38 sticker for the Badger State.  Therefore, free admission to this Wisconsin State Park is a nice added bonus for the NPS permit.

Confirming a NPOTA “3’fer”

The reason why I wanted to scout out the park is because it offers a unique opportunity to activate three NPS units.  I’ve already operated from the St. Croix Wild and Scenic River, which serves as the park’s boundary.  Therefore, any operation from the park within a hundred feet of the water will count as two units.  But the park also serves as the Western terminus of the Ice Age National Scenic Trail.  Today, I had to confirm that there was a location that would qualify for all three.

The National Scenic Reserve activation requires operation anywhere within the park’s boundaries.  And the River requires operation from within 100 feet of the river.  Operation from the Scenic Trail requires two things.  First, the actual operating location must be within 50 yards of the trail, and must be reached using human power.  In other words, it is not permissible to operate from a vehicle.  Therefore, I had to confirm that there was a location within 50 yards of the trail that is also within 100 yards of the water.  And the photos shown here confirm that there is indeed such a spot.


The viewing point just below the trail marker. The frozen river is directly below, as seen in the background.

The first photo at the top of this page is a marker indicating the Western Terminus of the scenic trail.  There’s a parking lot less than a quarter of a mile from this spot, and it’s an easy hike in.  The exact location of this boulder might be slightly more than 100 feet from the water, but the second photo shows an observation area, less than 50 yards from the trail marker, that is directly above the water.  There’s plenty of room for setting up a radio and a small antenna, and I’ll certainly be operating from this spot later this year.

I did talk to the Rangers to make sure they were aware of the NPOTA event.  One of them had already spoken to a local ham who planned to operate from the park some weekend.  They confirmed that there were no problems with operating from the park, as long as hams don’t get in the way of other visitors.  I reassured him that “Leave No Trace” principles were an important part of the NPOTA event.

I only had time to do a bit of operating.  While the kids were sledding in the park (no, not near a cliff over the river), I set up my mobile antenna and called CQ.  Unfortunately, this was at an elevation near the river, and it was a very poor location for RF.  Nonetheless, I did work three stations, one in Texas on 20 meters, and two in Colorado on 30 meters.  Interestingly, one of the stations I worked was also mobile.

Taking Advantage of the Reverse Beacon Network

I suspect that if I had been spotted on the DX cluster, I would have had a big pileup of stations looking for this still relatively rare unit, despite my poor operating location.  I had announced the activation, but I suspect that few would be patient enough to wait for me, since I was unable to predict the exact time of my activation.  However, this experience did highlight one tool that could be very helpful in locating weak NPOTA activations, the Reverse Beacon Network, an amazing system in which numerous receivers are constantly skimming the digital and CW bands looking for stations calling CQ.  As soon as they are heard, they are immediately spotted.

Here’s what the Reverse Beacon Network picked up from me today and made available to anyone who wanted to look for it on the Internet:


As you can see, I was 19 dB above the noise at at least one location, and copiable at many others.  In light of this experience, I encourage NPOTA chasers (and those operating similar events, such as Summits On The Air) to make use of this resource.  If you know that someone is going to be activating a park you need, but don’t know the exact time or frequency, simply search for that call at  Even if you don’t plan to work the station on CW, this resource could be very helpful.  Even if you can’t copy CW, you will get the exact frequency, and you’ll be able to hear them.  When they stop, there’s a good chance that they are moving to phone.  You’ll know how strong a station you’re looking for, and you can tune the phone band looking for them.

As an experiment, I did make a CW CQ on the phone frequency where I was frantically calling CQ.  I was hoping that the Reverse Beacon Network would pick up this call as well.  But as I suspected, it did not.  It appears that the skimmers of the Reverse Beacon Network are scouring only the CW portion of the band.  Therefore, the network can’t be used to self-spot in this manner.

However, even if an activator is planning on working mostly phone, it would be a good practice to work CW or digital first, before QSY’ing to phone.  Even if you don’t make any contacts on CW, it will let others know that you are on the air, and they will know to look for you on phone if you plan to operate there as well.

When conditions for outdoor operation get better, I encourage other activators to take advantage of the “3fer” status of this particular park.  The spot I located was on the “Pothole Trail,” which can be found on the park map.  For mobile activation of only the park, the best location is probably the parking lot of the Ice Age Interpretive Center, which appears to have the highest elevation of any of the parking lots in the park.  It also contains a number of interesting exhibits regarding the nature and geology of the park.  And it’s absolutely free, as long as you have a fourth grader willing to accompany you!

Missionaries Martyred in Ecuador, 1956


This month marks the 60th anniversary of the death of five American missionaries in Ecuador, Jim Elliot, Nate Saint, Ed McCully, Peter Fleming, and Roger Youderian. The five were taking part in Operation Auca, an ultimately successful attempt to evangelize the Huaorani, a tribe of about 700 spread out over about 7000 square miles of jungle.

Despite the initial setback, the effort was successful, after the Huarani realized that the Creator, with Whom they were acquainted through His creation, wanted them to abandon their warlike ways.

Sixty years ago today, the incident was featured in a prominent story in the January 30, 1956, issue of Life Magazine, entitled “Go Ye And Preach the Gospel: Five Do and Die,” from which the photo above is taken.

Much of the news of those events came to the attention of the world through HCJB radio.


117L7GT One Tube Transmitters, 1941

117l7xmtr75 years ago this month, the January 1941 issue of QST contained the plans for two one-tube transmitters, both using the recently introduced 117L7GT tube. The tube was ideal for a simple transmitter, since the filament ran directly off line current, and the envelope contained a rectifier and beam-power tetrode. Thus, the set could operate directly off line current, with no transformer required. The set shown above was made by R.T. Lawrence, W8LCO, of Dayton, Ohio. The schematic below is the similar set made by Keith Hayes, W9ZGD, of Milwaukee, Wisconsin.


Either set could be easily reproduced, with minimal part substitutions, from readily available components.  It should be noted that neither of these transmitters has much in the way of output filtering, so it would probably be necessary to add an output filter to comply with modern regulations.

In his article, W9ZGD reports what many modern QRP’ers have rediscovered:

Although 4 or 5 watts doesn’t sound like much input, it is surprising what one of these little transmitters will do, particularly to one who has never tried anything like it before. Possibley, according to tradition, I should list the stations worked but, since the antenna, receiver and operating ability affect the statistics as much as the transmitter power, I’ll just mention the fact that 5 watts give a signal about one “S” point lower than 20 watts and 2 “S” points lower than 80 watts. And, anyway, it’s more fun to fish with barbless hooks!

The W8LCO QSL card shown here is from the builder of the transmitter shown at the top of the page. The QSL was for a contact a few years earlier, in which he reports running 24 watts input.

National HRO Receiver, 1936


While interestingly not mentioning the name, 80 years ago this month, the January 1936 issue of Popular Mechanics contains a glowing review of the National HRO receiver. It stressed the set’s sensitivity and selectivity, and pointed out that the unique tuning dial represented a dial scale twelve feet long.  Without revealing the manufacturer or model name, the review simply describes the set as a “Short-Wave Receiver DeLuxe.”

The set was reportedly designed by Herbert Hoover, Jr., W6ZH, and Howard Morgan of Western Electric, with the design work done in Hoover’s garage. The set first hit the marked in 1935, with a price tag of $233, not including the speaker and power supply. Band switching was accomplished by changing the coil module below the tuning dial. Each coil came with an individually prepared calibration chart to show frequency, since the dial was simply calibrated between 0 and 500.

1966 Analog Computer


Fifty years ago, you would probably be the only one on your block with a computer if you built one of these. The January 1966 issue of Electronics Illustrated contains the plans for building this analog computer, suitable for addition, subtraction, multiplication, division, squares, and square roots.

Each dial is calibrated from 0-10, and there is a small ammeter.  For an addition problem, you set the switch to +/-, and adjust the two left knobs to show the numbers you want to add.  Then, you adjust the right knob until the meter is at zero.  Subtraction problems are done in the same fashion, except you set the right knob to the larger number, the middle knob to the smaller number, and the answer is shown on the left knob when the meter reads zero.  A similar procedure is used to do multiplication and division.  In the image shown above, the computer confirms that 5 times 4 does indeed equal 20.

For squares and square roots, a second section of one of the dual potentiometers is used so that both have the same resistance.  That dial shows a number, and the dial on the right shows its square.

The article points out that the device is basically the electronic equivalent of a slide rule (and probably much less accurate).  And like with a slide rule, you were on your own when it came to figuring out where the decimal point went.

I do remember in the elementary school library a book showing a similar contraption, which was wired up only for addition.  Instead of having three potentiometers and a meter used only for zeroing, it had two potentiometers and a meter from which the answer was read.  Despite thinking about how much easier that would make my math homework, that setup was probably much less accurate than the one shown here.

1966JanEI2Shown here are simplified schematics showing the circuit used for addition and multiplication.  The combined wiring diagram showing the switches is, of course, also included in the article.  But the simplified diagrams give a good idea of how the thing works.  Both merely take advantage of Ohm’s law.  R1 and R2 are one tenth the value of R3.  As might be guessed, the parts list calls for linear tapered potentiometers.

Click Here For Today’s Ripley’s Believe It Or Not Cartoon

Cuba-U.S. TV Broadcast Aircraft Relay

1956JanRadioElecSixty years ago this month, the January 1956 issue of Radio Electronics carried this item about a relay of a telecast from Cuba to the United States.  The program, carried by NBC, originated with CMQ in Havana.

Cuba was the first country in Latin America with television, and by 1954, it had a national network, with CMQ as its flagship station.

This 1955 program was relayed from atop a 35-story apartment building in Havana to an aircraft doing figure 8’s halfway between Havana and Miama.  It relayed the program to NBC’s receiving equipment atop the Fontainbleau Hotel in Miami Beach.

For more discussion of the use of aircraft to relay TV signals, see my earlier post about Stratovision.

POTUS to Military: Read The Bible


Imagine the outrage that would ensue if the President of the United States penned the following words, knowing that they would be distributed to most members of the Armed Forces:

To the Armed Forces:

As Commander-in-Chief, I take pleasure in commending the reading of the Bible to all who serve in the armed forces of the United States. Throughout the centuries men of many faiths and diverse origins have found in the Sacred Book words of wisdom, counsel and inspiration. It is a fountain of strength and now, as always, an aid in attaining the highest aspirations of the human soul.

But on this day 75 years ago, the Commander in Chief did exactly that.  This personal message by FDR was included in a pocket Gideon Bible (New Testament, Psalms, and Proverbs) distributed to military members.  And apparently no outrage ensued.

National Parks On The Air: Saint Croix Boom Site


Installing the antenna.

I rarely get a chance to experience a “pileup” on the radio, but today I was able to.  As I recounted in an earlier post, the ARRL is sponsoring an event called National Parks on The Air in which hams are encouraged to operate from units of the National Park Service and to make contact with those stations.  In addition to the 59 National Parks, this includes other units of the National Park Service.  Two of these are located within a few miles of my house, the Saint Croix National Scenic Riverway and the the Mississippi National River and Recreation Area.  Under the ARRL rules, as long as the station is within 100 feet of one of these rivers, it qualifies.

My assistant operator.

My assistant operator.

A close examination of Google Maps revealed that most of the parking lot of the Saint Croix Boom Site near Stillwater is within 100 feet of the river.  In addition, it’s at a high location above the river, which is better suited for radio transmissions.  And until today, nobody had activated this unit.  So this afternoon, along with my daughter, I set out for this location.  As with my previous activation, my station consisted of my Yaesu FT-817into a Hamstick mobile antenna mounted with a trunk mount.  The antenna, about six feet long, is shown in the photo at the top of this page.

Today, I operated for only about a half hour, but was almost immediately confronted with a pileup.  In just over thirty minutes, I worked 36 contacts:

Since I was on 20 meters, I had few, if any, contacts within a few hundred miles.  On that band, those close-in contacts are within the “skip zone,” meaning that the signals are reflected by the ionosphere only much further distances.  I believe my closest contact was Colorado, but I had contacts with locations such as California, Alberta, and New Hampshire.  The amazing thing is that I was using only five watts of power.  I was getting the power from the car (which I kept running for heat), but I could have just as easily made all of those contacts with the radio’s internal 8 AA batteries.  And my antenna, only about five feet long, is grossly inefficient.  In addition, as you can see from the photo, it was partially blocked by the car itself.  But it goes to show that if hams really want to make the contact, they’ll listen for the weak ones.

Google Street View of my operating location.

Google Street View of my operating location.

Living in the city, it’s easy to forget how close some of the natural wonders of the area really are.  and Saint Croix National Scenic Riverway includes a lot of gems.  In addition to the National Park facilities, at least four Minnesota State Parks border the river:  William O’Brien Interstate, Wild River, and St. Croix.  I’ve already identified several sites in their campgrounds that are within a hundred feet of the water, and I will almost certainly make more activations later in the year from one of these spots.

The site from which I was operating today is the Saint Croix Boom Site, which is just north of Stillwater on Highway 95.  In fact, downtown Stillwater is visible as you look down the river.  But as you look upstream and at the Wisconsin side, it’s clear that you’re at the beginning of the wilderness.

The historic marker at this site commemorates the St. Croix Boom Company, which was chartered by the Minnesota Legislature in 1851.  The St. Croix River Valley was a major logging area, and the loggers floated the logs down the river to mills.  Each logging company’s harvest was marked with a timber mark, and the St. Croix Boom Company was granted its charter to collect all logs and deliver them to their owners.  At the location where I operated today, the company operated a series of “booms”–logs chained across the river, to catch the lumber as it floated downstream.  Workers gathered logs and formed logs of each company into rafts, which were steered downstream to the correct mill, some as far south as St. Louis.  In exchange, the company was granted the right to charge 40 cents per thousand board feet.  The photo below shows the Boom Site in operation in about 1886.

Minnesota Historical Society photo, via Wikipedia.

Today, the site consists of three stops on Highway 95.  In addition to the historical marker from which I operated today, there is a stairway leading down to the river, a modern rest area just to the north, and a public access boat launch just to the south.  The site also marks the transition between the federal and state zones of the river.  Upstream to the north, the river is under the jurisdiction of the National Park Service.  Downstream to the south, the river is still designated as the  Saint Croix National Scenic Riverway, but is under the jurisdiction of the Minnesota and Wisconsin Departments of Natural Resources.

The Regenerative Receiver Turns 100


True to our name here at, we frequently feature one tube radios.  And more often than not, they are regenerative receivers.  The regenerative receiver was popular in the early days of radio because it could deliver so much performance out of a simple circuit.  The single tube, in addition to serving as the detector, had some of its output fed back into the tube to amplify.  If there was too much feedback, the receiver would break into oscillation, which would result in a squealing sound from the headphones, as well as those of other nearby receivers.  The anti-squeal campaign featured in an earlier post showed how this could be the bane of other local listeners.  But this oscillation also allowed the reception of CW (and later SSB) signals by simple receivers.

As far as I can tell, the regenerative receiver was first introduced to the public a hundred years ago this month in an article in the January 1916 issue of Electrical Experimenter.

An article by Frank J. Collins entitled “Regenerating Audion Circuits for Wireless Receiving” includes the circuit diagram shown above. If the circuit looks familiar, it’s because it’s the same circuit, with minor variations, used in most of the one tube radios shown on this site.

The details given in the article are for the construction of a longwave version of the set. “As most of the high-power transatlantic and transpacific stations use wave lengths of from 5000 to 10,000 meters [30 to 60 kHz], dimensions are given to cover these wave lengths only.” The author reports that with an aerial 500 feet long at least 10 feet above ground, reception of strong stations 2000-4000 miles away was possible, day or night, but that the set would work well with an antenna of 100 feet.

Drawing from Armstrong patent.

Drawing from Armstrong patent.

While this seems to be the first popular construction article showing how to make a regenerative receiver, it was a couple of years old by the time this article was written. It was invented by Edwin Armstrong in 1912 and patented in 1914 (US Patent 1113149).

The article warns that “while the coils described herein may be constructed by experimenters, they are not permitted to sell them to others for the purposes described, as the invention is patented.”

The author concludes by noting that “this type of apparatus and connections are well worth constructing and using, as it constitutes the most advanced means known at the present time in the reception of both damped and undamped radio signals.”

Because of the relative simplicity of the circuit, a regenerative receiver is an ideal project even today.  I have featured numerous examples in this site, most of which can be easily constructed using the vintage plans, although some parts require a bit of creativity to replace with modern equivalents.  Sets designed for the AM broadcast band will give immediate gratification, since there’s guaranteed to be something that can be tuned in immediately after making the last connection.  Shortwave sets are surprisingly good performers, and will pull in signals from around the world with little difficulty.

For those wishing to bypass the parts procurement process, a number of good kits are available.  For example, the kit shown in the illustration here is available at Amazon at a reasonable price. It’s a two-tube set that tunes both standard AM and shortwave.  For those who don’t mind substituting modern transistors for the tubes, puts out an excellent kit, the Scout Regen Receiver, It tunes only shortwave, but covers enough territory to almost ensure that you’ll be able to tune in something interesting, day or night.  At night, the dial will be packed with amateur, commercial, and shortwave broadcast signals from around the world.

My son and I put together the Scout Regen a few years ago, and it is an excellent performer for such a simple design.  One that appears to have similar performance, but probably a bit easier to put together because of its wide-open layout, is the Ozark Patrol receiver designed by David Cripe, NM0S and distributed by the Four State QRP Group.  If you build any of these, you’ll have a very sensitive receiver capable of pulling in many interesting signals, and you’ll also be working with the same circuit employed by experimenters a century ago.