Money for nothing and the chicks are free.

Those iconic words are from the British group Dire Straits. We have free info available to us from the blog stats and data from you tube. Sorry no chicks but the info is free.

Firstly, the you tube stats were an eye opener for me. There it was telling me all of the time why I am running an inefficient you tube channel. I have 2500 followers (a paltry number) and 368 videos. The single biggest viewing group are those 65+ and the smallest is under 40. Even the group between 40 and 65 is not that big.

Well 1st you would say that the ham population is older and so that would follow. Problem one is that those 65+ today by statistics will become smaller each year. The 2nd piece is the under 40 group is unimpressed with homebuilt stuff. In time they will be the 65+ and so what happens now is not suddenly going to change. If the under 40 group is not looking now, they won't be later.

The under 40 group has to be constantly stimulated with new unboxing video's, new rig reviews, and treks by good looking YL's up a mountain to operate their FT710's from a summit. Couple that with the license requirements that are void of anything technical, the hobby focus is totally shifted to contests and operating.

Very few hams under 65 could care anything about a homebuilt Hybrid SSB transceiver. There is no waterfall, no noise blanker and no identification with the "in crowd" as owning an IC7300 or knowing Menu 27 item three adds presence to your sound. There are no menus in the Hybrid Wireless set. Really significant: no interest in hams who design and engineer their rigs. The standard question what kit is it, shows their ignorance of the connotation homebrew.

The blog stats are another key indicator. Beyond the US viewers the next substantial viewership is from Germany and Vietnam. Combined over a 7-day period these two countries are 1/2 the number of US viewers. I am still scratching my head over that.

Blog viewership is down and I attribute that to content with my focus on older technology like vacuum tubes, projects that are too complex and perhaps my disgust and commentary with how this country is being run. We all are facing higher prices, but folks don't like to be reminded, and this is a turn off. 

The same factors as the you tube stats I would suggest prevails. My blog readers are an older segment of the ham population and little focus on the latest, brightest shining objects does not attract younger hams. 

Gulp a realization that my content is boring!

While putting my thoughts to the digital world is also a schedule filler and a challenge to my creativity, these days the effort exceeds the small number of readers. So, I will be posting less frequently if only to prove I am still alive.

It is like a notice I got in an email from my local Catholic church. No, my Catholic membership card was not canceled; but one of the masses has been eliminated from the schedule. There was a 5 PM Mass on Sunday evening. I think this was originally established for the Saturday night party goers who had a hangover on Sunday morning but by 5PM Sunday they were back to normal. The message was we are sorry, but the mass is cancelled as there were maybe less than 100 attending that mass and the church was empty. The same applies for this blog.

Too bad as I have an exciting project on the bench today that I won't be covering on the blog... too boring for the under 65 hams. 

Them that know will stop letting you know.

73's

Pete N6QW

Yesterday I bought a Yaesu FT710

 Yaesu FT710 with Tax about $1300

IC7300 Mark II with tax about $1600

FLEX 6700 about $3300

Yesterday I got an urge to buy an appliance box as I reached the point of not wanting to engage in building yet another SSB Radio. I wanted to feel the excitement of being the 45 Minute newly licensed Extra Class Awardee and go through the whole schmeer of making the unboxing video and running a BYOTA (Back Yard On The Air) contest for Zip 91320. It was exciting. Lest I forget the operating part, where in every QSO I mention my new radio and how good it works and sounds. Next in line may be a Mercury Amplifier.

As usual I looked at three bids and did a measured evaluation: Scanning You Tube Videos, looking at Groups.io and Discord Servers and in the process created a spread sheet of evaluative factors. The three contenders were the Yaesu, ICOM and FLEX appliance boxes.

I was amazed to find a core (read Pareto Principle) set of factors like 100 watts, good signal handling capability, small footprint, good for BYOTA, good reviews, compatibility with poor eyesight, FFS and diminished hearing and of course price. 

The winner and low bid from this analysis was the Yaesu FT710 coming in at full delivered price with tax at $1300. This is quite a step up for me as the last NIB radio I bought was 30 years ago and that was a Ten Tec Omni VI Plus. Plus, many blog readers know my penchant for rolling my own. If I can do it, then maybe good friend N2CQR will one day follow my lead and buy a NIB SDR radio.

I anxiously await the arrival of the FT710.

So, OK I didn't buy a Yaesu FT710 yesterday but did spend $1300 for 8 feet of wooden fence that blew down with the Santa Ana winds. The former fence posts made of wood had rotted and the whole structure simply fell over. The replacement posts are 3-inch steel box channel and won't rot. A seasoned crew of two did the whole job in 4 hours and was turnkey. Yes, that is a real orange tree of edible oranges

8 Foot of Fence with Gate $1300

Those prices I quoted for the ICOM and FLEX radios were actual alternate bid prices for the same fence task. It is imperative to get three bids and have a common set of evaluation factors.

I apologize for the bit of a ruse but in fact while I was on vacation in Denver last summer, I stopped at a ham store and twiddled the knobs of the FT710 and I was impressed. BTW the FT710 is #3 on Rob Sherwood's list of receiver test data, thus the low bid is high in performance. So, if N6QW were to buy an appliance box it would be the FT710. But $1300 did blow my budget for radio buys for 2026.

Them that know, now don't care if you know.

73's

Pete N6QW

Switching Sidebands in a Transmitter.

Most commercial built ham SSB radios made during the 1960' often touted as being cost effective (read cheap), provided coverage of the ham bands with only one choice of sideband. The SWAN 240 gave you LSB on 80 and 40 and USB on 20. The Hallicrafters SR-160 and even the National NCX-3 and NCX-200 had the same deal. Today that is viewed as a shortcoming.

It was the uptown radios that gave you a choice of sidebands. Even the venerable Bitx40 had only one sideband choice. I found a way to install USB/LSB on the Bitx40 by switching the LO from 5 MHz to 19 MHz for USB and that did the trick. Obviously with FT-8 you would like USB on 40M.

I had never thought of the way to do the USB/LSB process by using a fixed Mixer oscillator frequency to switch sidebands. This was not apparent to me until I saw the block diagram of the B&W 6100 produced during that time period.

This is really an interesting approach and although two blocks are labeled Balanced Modulator #1 and Balanced Modulator #2, the second one is a Mixer stage.

What happens is the standard Balanced Modulator (#1) with Carrier Oscillator at 3.2 MHz and an Audio signal from the Mic Amp, produces an output that is fed to an Upper Sideband Filter. Thus, all SSB signals start as Upper Sideband. 

From here the USB is fed to the Mixer (BM#2) and combined with the fixed crystal oscillator signal operating at either 12.4 MHz or 6 MHz. This is where the magic happens.

In the case where the Mixer oscillator frequency is at 12.4 MHz a subtractive mix is 12.4 - 3.2 = 9.2 MHz and the sideband is inverted. The signal now passes to a 9.2 MHz IF stage and is LSB.

In the case where the Mixer LO is at 6 MHz then the mix is additive so 3.2 + 6 = 9.2 and the sideband is not inverted thus we have a 9.2 MHz USB signals passing through to the IF stage (ALC).

Two more frequency translations occur with the VFO signal and a frequency translator operating in the 40 to 60 MHz range. The ultimate result was all band coverage (80-10M) with selectable sideband. This was leading edge technology, with vacuum tubes in the 1960's. 

I don't think many ham shacks had a B&W 6100 and in time B&W folded their tent. 

Most Crystal Filters for commercial radios are not USB only filters. However, I know that in the Drake Lines and in some of the oddball Swan gear they have separate USB and LSB Crystal Filters. Some of the homebrew filter topologies favor LSB and so this might be a trick to use with those filters. 

Things I never knew until today. But let us not pass too quickly over what was just presented. Looking at it today, there were some mighty smart designers here in the USA during that time. (Proudly I state that B&W was located in Bristol, PA.)

There is a reason why at that time so much leading-edge stuff originated here in the USA, and it is pure and simple. Our hobby had a strong technical grounding unlike today's 45 Minute Extra Class License awardees. Homegrown in the USA technical innovations in our hobby has been surrendered to the offshore manufacturers. You need only look at the top of Rob Sherwood's receiver test data list, and the radios are from Yaesu and Icom. A tip of the cap to the ARRL. You own it!

Them that know, now don't care if you know. 

73's

Pete N6QW

Magnetic Loop Antennas

 I know absolutely nothing about Magnetic Loop Antennas! The OT's used to say if you want to make contacts then build a dipole, put it in the clear, up 100 feet in the air and you are there. The thought of a 40 inch in diameter copper loop sitting 2 feet above ground does not sound like a DX antenna, or any kind of antenna. 

Gulp! A $2500 Mag Loop from Italy sold by DX Engineering

The best analogy I thought of for those using a loop: Taking your cousin to the prom and convincing yourself... she is a YL; but in truth is sort of unattractive, not a 44DD and your cousin.

So, why Mag Loops? I did do a bit of research on Mag Loops and found in truth they do work and are good in high noise environments and where hams are subject to space limitations or HOA's. They are not a one for one substitute for dipoles in the clear, at 100 feet so don't get too excited!

Basically, a Mag Loop is really two loops with the outer loop being in the range of 10 to 15 feet in diameter with the better performing loops being at least 0.5 inch in diameter copper tubing with the ends connected to a HV Variable Cap. The best caps are vacuum variables. More on that.

The second loop is 1/5 the length (20%) of the main loop and this connects to your transceiver or transmitter. Now the configurations seem to vary but most common has the smaller loop at the top dead center of the larger loop, and the feed point at the bottom of the smaller loop. The Variable loop tuning cap is at the bottom of the larger loop. The larger Loop is supported at the bottom typically on a small stand or tripod often only a few feet above ground. One feature of the Mag Loop not easily done with a wire dipole at 100 feet... it is rotatable for nulling out noise.

Now for the shocker: the loops are Hi Q with a limited tuning range once set... like 20-30 kHz (or smaller range). So, if you QSY (move frequency for the BTE's) outside that range you need a retune. 

The other big shocker if you run 100 watts into the small loop, the circulating current in the big loop might be 10 to 15 amps and the voltage across the Variable Capacitor might be the close to 3500 Volts. That is the why of the large transmitting cap or vacuum variable. The reason is that the two loops form a step-up transformer where magnetic coupling (the Mag part of Mag Loop) connects the two loops.

VK3YE, Peter Parker had a good solution for the HV capacitor problem and that is a chunk of LMR coax. Coax cable has a certain capacitance per foot. His trick: Find an approximate length of coax to resonate the loop and solder each conductor at the ends of the outer loop and at the other end of the coax it is open. Two feet is maybe like 50 to 60 Picofarad. But this limits you to one band and one small tuning range.

Below are two you tube videos. I must have sampled about a dozen how to make it You Tube Videos and for someone unfamiliar with how to build one, these two seemed to hit the mark.

The second one answered a question for me. So, you got the expensive copper tubing, and now the problem how you make it into a perfectly round circle? His answer was he covered his dining room table with newspaper that was taped down. Then using a stick as a radius went around the newspaper with a felt tip pen forming a visual template. The final step has the tubing follow the pattern. Nice. 

Bozos has 0.5-inch copper tubing in a 10-foot coil in the $50 range. A 40 Inch in diameter loop is 40X3.14159 in circumference or 125.7 inches. Divide that by 12 and you get 10.47 feet. The open ends of the outer loop are connected to the capacitor, so you make that opening 5.64 inches (use an insulated spacer) and you have a perfect 40 inch in diameter loop.

Reference #1

Reference #2

So after watching the two videos most hams conclude that it is too hard to build one (only 1% of hams homebrew) and so what can you get for less than $2500. Here is one commercial loop that is about 20% of the Italian offering.

Here is a link to the Alpha antenna website. By the time you are done adding in everything to make it work likely you will have spent close to the cost of an ICOM IC7300 (earlier version). But the Mag Loop may be the only solution for those who have significant noise issues and where other antennas may be impossible to install, such as an apartment or where there are prevailing HOA restrictions.

Safety Precautions: That circulating current can cause serious RF burns. Keep your hands off the loop while transmitting. One install caused me to shudder. The loop was made of large diameter copper > 1 inch in diameter and was installed on the ceiling of a shack centered over the operating position. I saw a high risk of frying the operator's brain... well, I think he WAS from the W5 call area.

Them that know, now don't care if you know.

73's

Pete N6QW

The Regen Receiver

Predating the Direct Conversion Receiver was the "Regen" (Regenerative). Invented by E H Armstrong in 1912, it was a staple of ham shacks from then up to even today. Hams have described the "Regen" as evil, possessed by the Devil, a cause for alcoholism, diabetes, loss of hair, insanity, jock itch, infidelity, divorce and even pes planus. 

How can a marvel of electronics be described in such terms that serve to be like the highway traffic accident... as we pass by we all look for the dead bodies. The answer is while the Regen is simple in terms of circuitry, they are finicky to get operating. A special coil with a Tickler tap seems to be the critical path.    

There were two notable regens sold as kits by Allied Radio known as the Knight Kit Space Spanner and the Knight Kit Ocean Hopper. You can find these two on eBay today in rough shape, missing critical parts and rusted for about $150. The Space Spanner originally sold for $13.95 and the Ocean Hopper $10.95. In 1958, my dad bought me a Space Spanner.

One of the most popular topologies today for the Regen is from a seminal QST article in September 2000 known as the Kitchin's Regen (N1TEV).

Sept 2000 QST

Of course, in typical QST fashion you have to have the article to find out how to build L1. This is all part of the evil aura surrounding Regens. I will try to find the info on L1. The follow-on text suggests a film can is the base for L1. You know like 35mm film cans --- that was before smart phones.

"A Simple Regen Radio for Beginners 

 Notes QST September 2000, pp, 61-64 

By Charles Kitchin, N1TEV  

Some readers have been asking for a more detailed circuit explanation for my beginner's regen radio project in the Sept 2000 issue of QST. This should answer most reader inquiries.  

A Detailed Circuit Description for "A Simple Regen Radio For Beginners" Project in the September 2000 Issue of QST.  

Although this circuit uses very few components, its design and operation are NOT simple. This project evolved through several (less effective) earlier versions and is the result of many years of experimentation and testing.

  

Coil L1 and capacitor C1 tune the input signal from the whip antenna. Regenerative RF amplifier Q1 operates as a grounded base Hartley oscillator. Its positive feedback provides a signal amplification of around 100,000. Selectivity is also increased as regeneration introduces negative resistance into the Q1 regenerative loop which reduces the positive resistance in L1 (and also the losses in C1). Since the Q of L1 is equal to XL/R, selectivity increases as regeneration is applied. The combination of the very low operating power of this stage, only 30 microWatts, with the use of a simple whip antenna makes this receiver extremely portable and prevents it from interfering with other receivers in the area.  

Q1 is a very high gain bipolar transistor. While it offers extremely high sensitivity, smooth regeneration control would not be possible without taking special precautions in the design. First, diodes D2-D4 are a simple voltage regulator that keeps the voltage powering Q1 very low, so that Q1 transistor operates at the bottom of its curve. I avoiding using a Zener here as I needed only 1.4V and I also needed to keep power consumption as low as possible (and silicon diodes are cheap and easy to find). Second, Resistors R1 and R2 provide a very large amount of negative bias which also helps to soften Q1's normally abrupt transition into oscillation. Finally, Potentiometer R2 controls regeneration and as R2 is adjusted to a lower resistance, Q1's gain increases (less bias) but at the same time R2's reduced resistance decreases regeneration by more heavily shunting the bottom portion of L1. These two opposing conditions help to linearize the otherwise highly exponential increase in regeneration as R2 is adjusted to a lower resistance. The resulting very smooth regeneration control is something not normally found with bipolar transistor regenerative circuits.  

Several important features of this design permit this circuit to have very good selectivity and also help preserve the high gain of the regenerative RF stage. First, a simple whip antenna is used. This does not load down the collector of Q1 and it also does not add any significant capacitance across C1 (which would otherwise reduce the tuning range of the receiver). Diode D1 and capacitor C4 are a "floating" detector that provides very high sensitivity with very little loading on Q1. Note that the relatively low back resistance of the 1N34 diode provides the necessary DC return path for the detector. The combination of a very high gain regenerative RF stage with a very sensitive signal diode provides a sensitivity equal to that of many superheterodyne receivers while only consuming about 16 microamps of power supply current (with R2 at mid position which is typically the threshold of oscillation).  

Volume control R5 sets the level of detected audio driving IC1, an LM386 audio amplifier. Capacitor C7 operates the LM386 at a gain of 200. In order to prevent any significant loading of Q1, both the bottom of the volume control, R5, and Pin 3 of the LM386 "float" above ground so that both inputs of the IC are AC coupled. This is very important. The LM386's output is internally biased at mid-supply. However, if the 100k Ohm volume control was DC coupled to the LM386 (bottom of R5 and pin 3 of the LM386 both grounded), the high input bias currents of a marginal LM386 device could cause a very large output offset to occur.....several volts of 

offset could easily occur as the LM386 has 50k input resistors referenced to ground and the LM386 has a typical input bias current of 250nA...250nA times 50,000 Ohms times a gain of 200 equals 2.5V (0.000250mA times 50k times 200). By floating the bottom of the volume control and pin 3 of the LM386, both inputs are now at the same DC potential regardless of the magnitude of input bias current (and both inputs "see" 50k to ground).  

Capacitor C5 provides low pass filtering that keeps RF out of the audio amplifier. Without it too much RF passes through the LM386 and into the headphones or speaker wiring then feeds back into the antenna circuit and causes motor boating on strong signals. C5 also improves the audio quality and slightly increases audio selectivity. Resistor R4 isolates the low pass filter from the detector circuit when the volume control is at the top of its range. Otherwise, the circuit would detune when the volume control was turned all the way up.  

Capacitors C10, C12 and C13 decouple the power supply line and isolate the RF and audio stages. Due to the long-time constant formed by R7 and C12, the detector will take approx. 7 seconds to start operating after the power switch is turned-on but operationally this is no big deal.  

Diode D5 protects the receiver if the battery is connected backwards. The coil, L1, is wound onto a standard 35mm plastic film can or 1 inch diameter pill bottle. I did not use a torroid here partly because it might saturate (and therefore detune) the receiver at critical regeneration but mostly because beginners want something that's easy to find and won't scare them off. Note that the selectivity is more than adequate (for a beginner's radio) using a film can coil form and therefore it is doubtful that a torriod would add any significant improvement here anyway (but it still might be interesting to try though).  

Capacitor C1 can be any air variable capacitor with 100pF to 365pF maximum capacitance.

Frequency coverage will vary with the capacitor used but all should cover the 40 meter Ham band plus several international broadcast bands. Note that using a capacitor with a large tuning range (such as a 10 to 365pF) will make it more difficult to tune-in a station than using a smaller capacitor (such as a 10-150pF). Therefore, the optional fine-tuning control is recommended when using large tuning capacitors.  

By increasing C1's capacitance (or increasing the turns on L1), this radio will operate all the way down to the AM broadcast band (and probably long wave as well). But it is important to limit the total tuning range, so that it is still easy to tune-in a station. That is why I am specifying the max. capacitance of the air variable to 365pF. Operationally though, a 100pF or 150pF value is best. You can always just switch-in extra capacitance to move down to a lower band.  A fine tuning control may be added to the receiver using diode D6 which functions as a poor man's varactor. As the voltage from fine tuning control R7 is increased, the diode is reverse biased and its capacitance decreases. This fine-tuning control is cheap and easy to add but its added capacitance will somewhat reduce the maximum frequency range of the receiver. You can compensate for this by removing turns from L1 (but keep the same ratio of turns for the tap if you reduce the total turns by 25 percent reduce the tap turns by 25 percent etc.).  Note that an audio taper control is specified for R8. This should be connected so that turning up the control causes an increase in voltage driving D6. The use of an audio (logarithmic) control helps to linearize the otherwise exponential decrease in capacitance as the voltage across D6 is increased. Note that capacitor C15 should be kept very small: 10pF MAX. Large values will give a greater capacitance (fine tuning) change but D6 will then start to load down Q1 and decrease gain and selectivity.  

With a whip antenna and weak stations (during the day etc.) this receiver is easily detuned by hand capacitance changes. There are several simple cures for this. A one- or two-foot length of wire can be clipped to the metal front panel or an external antenna (any random length of insulated wire) can simply be wrapped around the whip antenna. Be careful not to overcouple the external antenna as this will also cause loading on Q1.  

73  

Charles, N1TEV " [Found on the Internet.]

Now you know, direct from the author. He seems to be telling us that it took him a long time to arrive at this configuration and hopefully did not endure pes planus in the process.

Or for $50 you can buy a Regen Kit from a supplier in the UK. (Spectrum Communications.)

Regen Kit from the UK

The website for Spectrum Communications is here and Antony sells many hard-to-find components like 9 MHz and 10.7 MHz SSB Crystal Filters. The 10.7 MHz Filters are an interesting find for use with a 10.245 MHz mixer stage (a standard computer crystal) where one of the outputs is 455 kHz. Here you could use a Collins Mechanical Filter in a 2nd IF. Dual Conversion BTE's. To see that scheme check the N6QW QRZ.com page and look for the KWM-4 rig. 

Them that know, now don't care if you know.

73's

Pete N6QW

Multus Proficio MKII, A QRP SDR Transceiver

Meet the Multus Proficio, a 5-Watt QRP SDR Transceiver from the USA.

The MK II sells for about $425 and I have the MK I which was a bit cheaper. I have had my radio for a couple of years now operating with HDSDR. It does a pretty good job. (Regrettably it will not operate with Thetis or SDR Console.) Add a 100-watt amp and a laptop and you have a nice functional POTA station ready to operate from some park.

Multus has a custom (homebrewed) Software Suite and also has tagged on to QUISK with a special CW Suite. Multus traces its roots back to the Peaberry SDR board which featured an on-board codec. No external sound cards were needed for the I/Q encode or decode for the Peaberry.

True you are 1/2 the way to an Icom IC7300 (non MKII, 7300) but the radio will give you lots of capability for 1/2 the price.

St. Louis

I did two tours of duty in St Louis totaling 11 years and it was all about the job. I was paid well and it was a good place to raise kids, but it had an unmistakable terrible mindset. That mindset was the basis of my saying St. Louis is a great place to retire from not to! In between tours was a job assignment in Mesa Arizona where the same saying applies.

The McDonnell Douglas plant was physically located at the Lambert St. Louis airport. I lived in St. Louis County and that meant a 35-mile commute one way. In wintertime it was a dangerous drive.

So back to the mindset. During the Gulf War, I used my drive time listening to the news. My thoughts were always with our troops and remembering my time in the Seabees. That was the problem: the local news (mindset). 

The local news program on FM radio would start out: There was a major battle today outside of downtown Kuwait and now for the ball scores! The rest of the program was dedicated to baseball, football and hockey stories and/or including sports injuries and trades. Satellite radio would have cured that but not available in the early 1990's.

I am not a sports fan but am sure interested in world events. My interest peaked as two of my boys were draft age at that time. What a vacuum it was. Arizona followed a similar template with the overemphasis on sports.

We have the same issue today with the focus on old what is his name with stories like he spent two hours on X after midnight ranting about revenge and fair elections. Do we really care about cankles and suggested cognitive decline. What really is involved is his shifting the focus from the economy and people out of work to dribble about subjects that cause agita like renaming buildings. 

The media is to blame for the lopsided reporting on the latest antics. Stop reporting on the trivia and ask why so many layoffs in January. Big question: While shooting Americans seems like a new ice (ICE) sport what is the long-term path to citizenship plan? 

As Michael Douglas said in the movie The American President: "These are serious times for serious people." (This is not The Monty Python Clown Show!) Time to get serious and make your vote count in the Mid-terms. 

Them that know, now don't care if you know.

73's

Pete N6QW

BC-348 Receiver

 

BC-348 WWII Receiver

A ham friend who also grew up in Western PA shared his recent BC-348 video with me. He too dabbles in Boat Anchors... he has had more pass through his shack than me. I am in awe. He also reads the blog.

But three pieces of information for other blog readers and the 1st is the power supply. Many WWII vintage radios on eBay lack power supplies as the source of power especially those used in airplanes was a dynamotor. 

For those with a question mark on their face, a dynamotor was a small motor generator set running usually off of 24VDC that supplied all the operating voltages. Read noisy. 

The small ARC-5 receivers had a space on the back where the dynamotor attached. Often the filament string (transistors weren't invented as yet) was series/paralleled to operate from 24VDC.

The BC-348 had an internal space to install the dynamotor. The 1st important point the video shows how a $30 switching power supply from BOZOS can power the BC-348 and fits in the space where the dynamotor would attach. This power supply could be used for many other WWII surplus receivers.

The second point is the radio itself as it was as much electronic as mechanical assemblies (to switch bands). Keep in mind these radios were designed in the late 1930'w... No Internet, No Computers, No Nano VNA's and no Transistors or IC's. I marveled that the VFO had set points for various bands. In other words, you can calibrate the VFO at 5 MHz WWV and then a separate set point for 10MHz WWV.

The third point and that is radio tuned from 1.5 to 18.5 MHz, operated AM and CW and no band spread. Dial markings could be as much as a 100KHz apart. It struck me that the BC348 could be the principal receiver on a B-17 traveling across the Pacific and was the sole piece of long-distance communication receiving equipment. Good Luck!

Today's hams have no clue about WWII radios like the ARC-5, BC-348, HRO or ART-13's where 30 Hertz off frequency was routine. They have no clue that these radios were manufactured without using AI, Computers, sans solid-state devices or Nano VNA's. I guess the answer from this BTE set... who cares. 

Well in fact somebody cared as it was the shortcomings of these earlier radios that formed the basis of the designs we have today. 

Think about in the video how the 5MHz WWV set point was done. Now the military radios (SDR) have BITE (Built In Test Equipment). When the radios are placed in this mode there is GPS Disciplined Oscillator at 10MHz that readjusts all oscillators to that standard. A flick of a switch and in 1 second you are on frequency. 

Them that know, now don't care if you know.

Here is what Mr. Carlson did with a BC-348.

73's

Pete N6QW