Mid-Atlantic Antique Radio Club - MAARC

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Mid-Atlantic Antique Radio Club - MAARC

The Mid-Atlantic Antique Radio Club (MAARC) is a hobby club for those dedicated to collecting, restoring, and preserving vintage electronics. Join MAARC!

MAARC is a club for those dedicated to collecting, restoring, and preserving vintage electronics, including radio, television, hi-fi, vacuum tube, electronic test equipment, tube audio, and yes, vintage computers and computer games. Collecting antique radio, television, hi-fi audio/stereo, electronic instruments, and test equipment is a fun and interesting pastime that appeals to a variety of folk

s. Members include pure collectors who are looking for their next great find, technicians and tinkerers who like to restore the electronics or refinish cabinets, historians and preservationists interested in the history of the technology, and those who are into it as a small business. Many involved dabble in several of these areas. All enjoy the camaraderie of a shared interest. You will find vintage electronics collectors to be a friendly and honest group who do not take themselves too seriously, while recognizing they are preserving a part of our heritage. How Will MAARC Benefit Me? MAARC meetings and our Radio Age journal provide presentations and articles covering all aspects of our interests in vintage electronics. This covers everything from repair techniques, to cabinet refinishing, to test equipment, to tube collecting, to electronics history. Looking for a little fun? MAARC members enjoy hanging out with techies who share similar interests and pas-sions. We hold a banquet and restored equipment contest at our annual RadioActiv-ity event. MAARC Offers You the Opportunity to Buy or Sell Vintage Electronics. All MAARC meetings feature a flea market tailgating period and an auction. Both provide the opportunity to buy and sell old radios, hi-fi audio, ham equipment, tubes, vintage electronics parts, service equipment, and literature at good prices. Monthly meeting tailgate sales are without any fees. Auction buyers pay no fees, while sellers pay just a small commission. Of course, there is no guarantee that all items will sell, though most do. The monthly auctions tend to be more informal, with no minimum bids and often, no reserves. Because of the prices typically realized, the monthly auctions tend to be good opportunities to buy and sell lesser quality items and parts. Twice a year we offer larger meets with bigger flea markets and auctions. These larger auctions have higher quality offerings and are more likely to garner better prices. They may have minimum opening bids, consignment limits, and other policy requirements to help manage the auction. These two events, RadioActivity and RadioFallFest, are normally in June and October respectively. Guests are invited to our monthly 3rd Sunday meetings in Davidsonville, MD (Feb, Mar, May, Jul, Aug, Sep, & Nov) or Centreville, VA (Apr & Dec). Tailgate sales for these events start at 11:00 AM, with the meeting, including a Show and Tell and a topical presentation at 1:00 PM. This is followed by an auction of a wide variety of vintage electronics. Our October Fallfest in Davidsonville kicks off at 7:00 AM with a huge auction at noon. Other events include our January Winterfest at the National Electronics Museum (NEM) in Linthicum, MD near BWI airport, and our 3-day RadioActivity event held in June at a conference facility within the DC/Baltimore region. MAARC members receive monthly issues of our vintage electronics journal Radio Age (containing interesting and in¬formative articles), on-line access to past MAARC Newsletter and Radio Age copies and to the club's members-only Internet discussion forum. If you are a member of either NEM or the National Capital Radio & Television Museum (NCRTV), you get a onetime first year MAARC dues discount ($20 vs. $24). MAARC created NCRTV, which offers photocopies of service literature at low cost (see NCRTV.org.) For additional information, visit our website:
WWW.MAARC.ORG

06/05/2026

A brief post for this second day of our RadioActivity Vintage Electronics Expo. This one comes to us courtesy the "At The Controls" page and author Sean Brady.

"1924: WLS — call letters that represented Sears, the “World’s Largest Store” — signed on the air for the first time with a train whistle. WES, which stood for World’s Economy Store, would broadcast first on April 9, 1924, from a studio in Chicago on the 11th floor of the Sears-Roebuck tower. The company’s drafting room served as a control room. It moved to the Sherman House Hotel for its inaugural broadcast on April 12, 1924, and became WLS."

Pictured is Curtis D. Peck, radio operator at station WES, which changed its name to WLS after several days of transmission.

102 years later, WLS is still on the air. A Google search provided this WLS recap: Originally launched as a service for Midwestern farmers, the station transitioned through iconic eras of country, Top 40 rock, and talk radio over the last century. Sears originally created the station to reach rural customers and promote its massive catalog business. Shortly thereafter, still in 1924, WLS launched the National Barn Dance, which became one of the most popular country and western music shows in America and a direct precursor to the Grand Ole Opry. Sears sold the station to Prairie Farmer magazine in 1928, and the station shifted its focus toward agricultural news, market reports, and family-friendly entertainment, cementing its status as a vital voice for the rural Midwest. In 1960, ABC took full ownership of WLS and completely overhauled the format to Top 40 Rock and Roll. WLS became known as "The Big 89," with legendary radio personalities like Dick Biondi and Larry Lujack shaping the sound of Chicago radio. During this time, it was one of the most influential "clear-channel" stations in the country, with a signal that could be heard across much of North America at night. As FM radio began to dominate music broadcasting, WLS shifted its format to News/Talk in August 1989. Today, WLS (AM 890) features a lineup of conservative talk radio, local news, and sports coverage, maintaining its legacy as one of the most historic call letters in American broadcasting.

Anyone ever listen to WLS? Tell us about it.

06/04/2026

A quick post (and then some commentary) today as we kick off our RadioActivity - Vintage Electronics Expo in Annapolis, MD (use this link for more details: https://maarc.org/radioactivity-2026/). The post addresses a similar scenario antique radio clubs are now facing regarding missed opportunities, in this case the 1970's citizen band (CB) radio craze. It comes to us from the Ham Radio 24-7 page.

The FCC was processing 500,000 new radio licenses a month. Ham radio had 300,000 operators total. And we did nothing.

The CB Revolution: Ham Radio’s Greatest Missed Opportunity 📻

The 1970s were electric. Literally. The Citizens Band craze swept America like nothing before or since. At its peak, the FCC was processing 500,000 new CB license applications per month. An estimated 50 million Americans picked up a mic and said “Breaker, breaker.” 🚛

And the amateur radio community largely watched from the sidelines. Those 50 million people were already stringing antennas, tuning standing wave ratios (SWR), and chasing skip (off the ionosphere). They were proto-hams in every meaningful way — they just needed a nudge, a mentor, and an invitation. Instead, many in the ham community looked down on CBers as undisciplined “lid” operators who didn’t belong on the spectrum. 😬

The missed opportunity is staggering. Ham radio had 300,000 licensed operators at the time. A 1% conversion of the CB crowd would have doubled that overnight. A 5% conversion? Millions of hams — and a community with the political weight to defend radio spectrum for generations.

Every generation has its CB moment. Today (in the ham community) it’s software defined radio (SDR) dongles (radios you plug into the USB port on a computer that allow for listening to almost any frequency band used for communications), LoRa (standing for Long Range, in the context of ham radio, it includes low-power, wireless digital radio modulation techniques that allows devices to send small chunks of data over massive distances while using very little power), and YouTube antenna builders saying “huh, that’s kind of cool.” 🔧 The question is whether we reach out — or watch from the sidelines again. The door is always open. We just have to remember to put up a sign. 🚪73 (ham radio lingo for 'have a nice day') 🖐️Was the ham radio establishment’s attitude toward CBers the biggest self-inflicted wound in the hobby’s history?"

So, how does this relate to antique radio clubs? In the mid 1980's on into the 1990's, antique radios were in their craze days. Folks were buying antique radios as investments - buying them for a good price, getting them restored, and selling them for more than they paid for them. The antique radio clubs were growing by leaps and bounds. Within 10 years, by the mid 1990's, MAARC had nearly 1,000 members from all over the United States. Fast forward, MAARC now has just under 450 members. Antique radios that come into our auctions are selling at very low prices, 1/2 to as low as 1/10th what folks were willingly buying them for in the 1990's.

Yet, there is still a strong interest in vintage electronics, which I define as the broader realm of electronic devices that are restorable. By this, I mean they have elements with discreate components that can be replaced by the average hobbyist. This interest includes multiple aspects, both technical and historical. What are today's crazes? They include HiFi and music amplifiers, and computers and computer games. The HiFi realm is multifaceted. Vinyl records and vintage record players are hot. Tube-based Hi-Fi and music amplifiers from the late 50's and 1960's are highly sought-after. Many of the HiFi and music amplifiers manufactured today use the same vacuum tubes that were developed in the middle years of the past century (the 1930's through 1960's). Computers and gaming consoles from the later parts of the past century used replaceable circuit boards and integrated circuits that plugged into DIP (dual in-line package) sockets. Getting any of these devices operational requires the same skills needed to restore antique radios, skills that enthuse many hobbyists. Many folks also enjoy the historical aspects of the vintage electronics hobby. This might include the story behind the development of radar, or tube-based computers, or the growth of radio and TV broadcasting to name a few topics.

So where am I going with this? Antique radio clubs need to morph, and most are. They are shifting their focus, expanding it into the boarder vintage electronics realm. Are there still antique radios that are highly sought-after? Yes, and there always will be, either because of their unique styling or sound quality. But in general, the interest in these radios has waned. What may be a turnoff to many is the term 'antique.' This equates to Grandma's living and dining room decor. Yet the same skills needed to restore a mid-1950's All American Five radio are the same ones needed to restore that mid 1980's personal computer. The 'antique' electronics from the 1920's through the 1960's that were all the craze in the 1980's and 1990's are now, 40 years later, the 'antique' electronics from the 1960's through the year 2000, that include HiFi, classic guitar amps, and early personal computers and gaming consoles. Younger vintage electronic enthusiasts just don't like to refer to them as 'antiques.' They prefer 'vintage.' But as William Shakespeare appropriately stated, "A rose by any other name would smell as sweet."

What are your thoughts? We would love to hear.

06/03/2026

Today's post comes to us from the May 1993 "MAARC Newsletter" and addresses the Sparton Nocturne, one of the most sought-after radios ever produced. The article was written by Bill Engstrom.

"Perhaps the most expensive radio in today's collecting world is the Sparton Nocturne (see photo), a 1936-vintage art deco, 46-inch round mirrored console, which currently sells for more than $25,000. It is the dream of most antique radio collectors to see one of these rare specimens somewhere someday. To be involved in the restoration of one of them is something which I never expected when I got hooked on this hobby about three years ago.

As most collectors have found, the search for antique radios to purchase and restore is becoming a real challenge as more and more people join the radio collecting ranks. Like many collectors, I visit antique dealers wherever I find them, both where I live and where I travel. After purchasing a number of table model sets from one of the local antique dealers, I was discussing with him the fact that some of the Sparton mirrored radios of the 1930s were quite valuable. He then mentioned that he knew of a Sparton mirror radio in a warehouse in Portsmouth, VA, where his father (also a dealer) had some antique furniture stored.

He asked me if I could restore it for him, and I said I would take a look at it when he brought it to his store. A few months later he called me to come and check it out. I assumed it would be a Sparton Bluebird (valued at $3,500) or one of the other more common small mirrored Spartons.

When I entered the storage area of his store, I was surprised to discover that it was a Model 1186 Nocturne in fairly good shape (see Fig. 1). It was missing one of the side mirrors, the cabinet needed attention, the speaker was missing, and one of the k***s was missing. But it WAS a Nocturne!

The radio was so bulky and top heavy, I had to remove the chassis from the cabinet to transport it to my shop. The first thing I did when I started on the project was to remove the mirrors and the heavy metal frame from the cabinet. Then I inspected carefully all the various parts of the radio and made a list of the things that had to be done to accomplish the restoration. The list included getting another k**b, reveneering the cabinet, finding a piece of 1/4" blue plate glass to replace the missing mirror, locating a speaker, getting the metal frame parts rechromed, testing and replacing tubes, and getting the mirrors resilvered.

A restoration of this size needed a plan, which I put together with a tentative timetable and a list of possible suppliers for the missing parts. I felt that it should be possible to complete the project in about six months. Little did I realize how difficult it would be to complete the job in that timeframe.

I had the cabinet reveneered with no problems by a local antique refinisher. Locating another k**b was a greater challenge, since the original k***s appeared to be stainless steel. After trying to get a k**b made locally with little success, I sent one of the k***s to my brother, who is a tool and die maker.

He found that the Nocturne k***s are actually chrome-plated brass, which has the appearance of stainless steel. He was able to make a duplicate of brass and returned both k***s to me for plating.

Locating a speaker was not a difficult task either, since a friend of mine gave me a Hammond organ 12" speaker with an electrodynamic field coil, which I thought would work. The next task was to locate a piece of cobalt blue plate glass, 1/4" thick and about 20" by 40" in size. I found that this shade of blue plate glass hasn't been made since about 1941, and that I would have to locate a piece of used glass somewhere and have it resilvered. That search took about 10 months before I located a radio collector in Texas with a supply of used plate glass of the correct shade and thickness. He agreed to have a piece cut and resilvered for me if I would supply him with a pattern. Three months and two shipments of glass from Texas later (the first shipment arrived scratched), I finally had the glass problem partially solved. The next project was to find a source for having the rest of the mirror sections resilvered. After much searching, located a small firm within 40 miles of my home that was able to perform the work.

The chrome plating of the steel support frame and the k***s was a project which turned out to be almost as difficult as the glass mirrors. The k***s ended up in three different plating shops and the steel support frame in two shops before I finally got that part of the project completed to my satisfaction. It had taken about a year!

The chassis (see Fig. 2) was in very good condition, with no rust, and required only cleaning. I replaced three or four of the tubes, and all of the capacitors. The remaining problem was to locate an audio output transformer to operate the speaker. Since the Nocturne uses 6F6s in push-pull for the audio output stage, I had to find another set with a push-pull (center-tapped) output transformer with sufficient power handling capacity. Another friend came to my rescue and pulled one from one of his parts sets.

Finally, after eighteen months of effort, I had all the parts back and proceeded to reassemble the Nocturne and see if it would work. To my surprise, after minor alignment and testing, I was able to get reception on all the shortwave and AM bands. It is one of the most powerful sets I have ever heard.

Once the Sparton was assembled (see Fig. 3), I was eager to get such a valuable set out of my shop and into the owner's home. But when he picked up the set a few days later, I felt as though I had lost a friend. I doubt if I'll ever work on another Nocturne again."

As you can see, the photos from the original article were a little difficult to see. But we couldn't address such a magnificent radio without getting some better images. My search also uncovered some additional text I need to share.

The introductory color photo came from the Nocturne Radio page from the High art museum (https://high.org/collection/nocturne-radio/). Here is what that page told us about this radio.

"Title - Nocturne Radio

Artist - Walter Dorwin Teague (American, 1883–1960), designer

Maker - Sparton Corporation, Jackson, Michigan, est. 1900, manufacturer

Date - 1935

Medium - Blue mirrored glass, wood body, and chrome-plated and lacquered metal trim

Credit - Purchase in honor of Linda Teetz, President of the Members Guild,1997-98, with funds from the Decorative Arts Acquisition Endowment, Accession # 1998.35

Walter Dorwin Teague’s Nocturne radio is one of the most memorable and remarkable icons of the Machine Age in America. Geometric and classically balanced, the radio is one of the most forwardly modern expressions in American design from the 1930s. The circular reflection of the blue mirror together with precise chrome strips gives the radio a strong aesthetic impact. At the time of its introduction the radio retailed for $350, which put it out of reach for most Americans. It was often used in public spaces such as hotel lobbies; a smaller version called the Bluebird was also available. It was appropriate that this strong machine aesthetic be applied to a radio, which by the mid-1930s was the most advanced and widespread entertainment medium."

The "Radios Past" website also has a Sparton Nocturne page (https://radiospast.com/2019/10/sparton-nocturne/). Here are some excerpts from that source:

"For some collectors, the Sparton Nocturne is the ultimate radio. It came in a choice of blue or peach colored mirrors (see photo).

The practical workings of the chassis and speaker are hidden in a large wooden box behind the beautiful mirror (see photo).

The main reason there are not many Nocturnes is because they were very high priced for 1935. The $350 price tag was about the same cost as an automobile. These radios were meant as lobby displays for high class hotels, not for use in typical homes. The other thing is that it’s likely many of these radios ended up with broken mirrors. After 84 years, it would be interesting to know how many of the surviving Nocturnes still have their original glass.

Today, that $350 price doesn’t seem very high when you consider that the value of one of these radios is closing in on $100,000. A Sparton Nocturne sold for $95,000 in 2017. (Update: The highest known auction price is $149,000.) The cheapest one I’ve heard about was $40,000. Of course condition is a key factor, along with whether two really serious buyers are at the same auction.

Most Sparton radio buyers in the 1930’s opted for the much smaller table radio (about 14-inches in diameter), the Bluebird (see photo - Spartons from the collection of Hugh & Jane Hunt). It sold for about $40. The Bluebird was also designed by Walter Dorwin Teague. They’re highly collectible, and normally sell for $2,500 to $5,000.

The chrome & glass Sparton radio models reflect industrial art at its best, and certainly deserve to be in museums."
As I was researching something else, I tripped across this Tidbit from the November 2003 issue of “Radio Age:” “Wow, Mom. Just as this was being put together for the printer, along comes an eBay spectacular. Someone put a Sparton Nocturne up for auction, with a $9.99 initial bid. By 26 October, when I wrapped this issue up, the final bid came in, at $35,000. The Nocturne, of course, is a floor model mirrored set; this one had one broken mirror section, and the other sections needed resilvering. All the metal finishes were rusted, as well, so this set would need some careful restoration. It is still regarded by those in the rare deco radio market as a bargain at $35,000, as some semi-restored units have fetched up to $70,000.”

Anyone have a Sparton Nocturne? How about a Sparton Bluebird? Send us photos.

06/02/2026

More catchup for today, but first, a reminder that our Vintage Electronics Expo - RadioActivity 2026 starts in just 2 days. Don't miss out on the fun (see photos). For more details, visit our website at https://maarc.org/radioactivity-2026/

On 24 May we had the International Electronics Quiz, with one of the so-called voltaic pile identified as the earliest battery known, attributed to inventor Count Allesandro Volta of Italy in 1800. Ed Lyon pointed out there may have been an earlier battery, and pointed me to the Tidbit article from the November 2003 issue of "Radio Age".

"We had always thought that Alessandro Volta was the first to build a "Voltaic pile," in the 1793-1800 period. He dipped two dissimilar (copper and iron) metals into a weak acid solution, and obtained a sustained current flow when they were connected into a circuit. But in 1936, at Khujut Rabu'a, near Baghdad, an archeologist named Wilhelm Koenig claimed to have found an apparatus shown in Fig. 2, described by him as a silver jar containing a copper cup with an insulated iron rod in its center. But later examples, also found at the same location, have the jar made of clay or ceramic. The copper is insulated from both the iron rod and silver (or clay) outer jar by means of pitch or asphalt. If the jar and cup are filled with any acid, or wine or fruit juice, it forms a 2-Volt Voltaic cell. Koenig, helped by the Baghdad Museum staff, had dated the jar to the Sassanides dynasty, around 400 A.D. (plus or minus 200 years), but other archeologists date the copper and iron "electrodes" to a period nearer 200 B.C. This primordial battery was described by W***y Ley in a 1939 issue of La Nature, a French journal, and it was described briefly in Radio-Craft for July 1939; the battery (or whatever it is) is also now seen on the web at www.unmuseum.org/ bbattery.htm. Now, I'm sure the conspiracy theorists see this as definitive proof of the invasion by highly advanced aliens back in those good old days, one of whom probably dropped some Martian Energizer cells from his transistor radio while looking for the spaceship one night. The radio has not been found." Thanks Ed for setting us straight, but glad we call them volts rather than baghdads, much easier to spell.

On 26 May we had a post on Amateur Radio Emergency Services. Ed Lyon passed this on: "My late wife, Millie was for a good many years the “Secretary” or sole office support for MARS, the Military Affiliate Radio Service, located at Ft. Detrick, MD. She worked with the state Army and USAF MARS groups for all the states east of the Rockies to coordinate their support of emergencies and practice exercises, coordinating with the Hams. The MARS operating frequencies are next to the Ham bands, in general."

I personally benefited from MARS. As a young Ensign/LTJG in the U.S. Navy, I would find my way down to Radio Central on lonely in port duty nights while in the Mediterranean on a 6 month deployment, and ask a radio operator to call into a MARS affiliated ham who offered phone-patch capabilities to talk to my then sweetheart back in Virginia. It always took her a while to remember to say 'over' as she concluded her portion of the simplex conversation.

On 27 May we had a brief post about a British Spy Radio. Ed Lyon filled in the blanks, posting this: "It was a Mk-III transmitter that the N**i troops captured in Czechoslovakia upon the N**i take-over of that country. They displayed the set and all its associated gear in a popular storefront window in Prague with a big sign that bragged how clever the N**is were to capture this “criminal wireless setup…” but they had the actual transmitter unit on display upside down, as they didn’t understand what it was, exactly, but guessed it was evil and shameful. I think that I showed that storefront picture in a "Radio Age" article. Oddly, most of the wartime British spy radios used US tubes, probably to imply that the British were enjoying imports of such gear from the US, possibly in limitless quantities.

The Mark III was followed by the Mk V, built into a suitcase, or in two separate boxes, depending on where and when they were used by French underground. It had a four-tube receiver, (all US tubes, 3-6SK7s and a 6X5 rectifier) and a three-tube transmitter, 6V6 crystal oscillator and an 832 squat dual beam tetrode, with the tetrodes tied in parallel. An alternative design, also called Mk V, had TX and RX in the same case, the receiver using two 6SK7s and the transmitter using 6V6 an 832 again, with a 5T4 rectifier.

The British also had several versions of the Mk VI, another suitcase set, and they also made the most used model, the Mk VII “Paraset” about which I had a "Radio Age" article.

I have a complete four-piece US spy set called RS-6. The four pieces are a transmitter, a receiver, and a power supply, and another case with power supply filters and miscellaneous components. They were re-issued after the war for use by the Air Force, specifically the B-47 bomber fleet. Each B-47 had a complete RS-6 setup stowed in the back of the pilot’s seat, in case the plane had to land somewhere in the middle of Russia while on a mission. The KC-135 tanker aircraft were not to enter Russia on any mission, so that the B-47 might not have enough fuel to get there, drop its load, and get all the way back out to where the Tanker could refuel the Bomber so it could get home again.

Meulstee’s Wireless for the Warrior, Volume 4, has all these and many many more such sets described."

What a wealth of knowledge. Thank you Ed.

And that wraps up our catchup. Thank you all for your comments. They enrich our understanding of the vintage electronics hobby.

06/01/2026

Today's post provides the answers to yesterday's Capacitor Circuit Quiz. Here is a good quiz on calculating total equivalent capacitance for circuits containing various combination of series, parallel, and series-parallel connections. It appeared in the June 1968 issue of Popular Electronics magazine. To help in calculation, all of the individual capacitor values are the same. Many of them you can probably solve in your head, especially if you mentally rearrange the circuit into a more readily recognizable configuration. For instance, circuit #1 can be redrawn having two parallel branches across the source. One branch has just a single capacitor while the other has two parallel capacitors in series with one capacitor. The equation is then C + (2C2/3C) = C + 2/3C = 5/3C. For C = 6 pF, Ctotal = 5/3*6 pF = 10 pF.

Capacitor Circuit Quiz - by Robert P. Balin

Capacitors are not only used as single units in electronic circuits, but are often combined in series or parallel with other capacitors. When connected in series, capacitors add like resistors in parallel. The exact formula for adding any two out of any number of capacitors in series is: CT = C1 x C2/C1 + C2. When connected in parallel, capacitors add like resistors in series, so that the total capacitance is equal to the sum of the separate values. To test your skill at working capacitor problems, try to find the total effective capacitance available in each of the circuits (1-10) shown below. Each capacitor is rated at 6 pF. Hint: Beware of capacitors that might be shorted out.

And the answers are:

1) 10 pF
2) 6 pF
3) 12 pF
4) 9 pF
5) 16 pF
6) 8 pF
7) 5 pF
8) 3 pF
9) 15 pF
10) 4 pF

How'd you do? Did you get Honorable Mention?

05/31/2026

Last Sunday in May, so, time for another quiz. But first, an update on our upcoming Vintage Electronics Expo - RadioActivity, starting on June 4th in Annapolis, MD. As of Saturday, there are still 9 open spots for outdoor vending, 3 indoor vendor tables, and 10 seats available for our Friday night banquet, Need more details? Click on this link: https://maarc.org/radioactivity-2026/

Now, back to the quiz. This one is entitled the Capacitor Circuit Quiz, and is a good one for practicing the art of combining capacitors to get that unique value you are seeking when using parts on hand. The quiz involves calculating total equivalent capacitance for circuits containing various combination of series, parallel, and series-parallel connections. To help in calculation, all of the individual capacitor values are the same. Many of them you can probably solve in your head, especially if you mentally rearrange the circuit into a more readily recognizable configuration. For instance, circuit #1 can be redrawn having two parallel branches across the source. One branch has just a single capacitor while the other has two parallel capacitors in series with one capacitor. The equation is then C + (2C2/3C) = C + 2/3C = 5/3C. For C = 6 pF, Ctotal = 5/3*6 pF = 10 pF.

On to the quiz:

Capacitors are not only used as single units in electronic circuits, but are often combined in series or parallel with other capacitors. When connected in series, capacitors add like resistors in parallel. The exact formula for adding any two out of any number of capacitors in series is: CT = C1 x C2/C1 + C2. When connected in parallel, capacitors add like resistors in series, so that the total capacitance is equal to the sum of the separate values. To test your skill at working capacitor problems, try to find the total effective capacitance available in each of the circuits (1-10) shown in the photo. Each capacitor is rated at 6 pF. Hint: Beware of capacitors that might be shorted out.

Hey, give it a shot and post those answers with an Honorable Mention goal.

05/30/2026

More catchup for today, all on crystal sets.

On 23 May we had a post on home-brew crystal sets that brought back some memories. John Foell posted " When I was a kid in the 1960s my brothers and I built "Foxhole" Radios - essentially a crystal set with a rusty razor blade and pencil "lead" (graphite) detector. The blade had to be at a certain level of rustiness for it to work. These radios are variations of a simple receiver built by POWs and soldiers in WWII and on. We lived in upstate NY about two miles from the local 1,000 watt daytime only station so that one came in loud and clear and once in a while we got "DX" from nearby (20-50 miles) town stations. There is a certain "magic" in picking up stations for "free" with the simplest of apparatus. Just google "Foxhole Radio" and numerous references will list."

Ed Lyon shared "From 1938 until 1940, all I had was a series of home brew crystal radios based on the Boy Scout Manual designs, as it wasn’t until Christmas 1940 that I got a pair of 8000-ohm Cannonball headphones (as a Christmas present), and could actually hear radio stations with the crystal radio. I made that crystal set from a Quaker Oats box wrapped with enameled wire that I tapped every five turns (actually 5 ⅛ turns) by stopping the winding and twisting a tiny loop in the wire before continuing with 5 ⅛ more turns, then another tiny twisted loop, etc., for a total of 70 or 80 turns. The tiny loops became taps which could be contacted by a clip on the end of a wire that went to the antenna, a 50-foot-long insulated wire that ran under the window to a tall pear tree in the back yard. My headphone bypass capacitor was made from tinfoil from one of my father’s cigarette packs and waxed paper. In those days, the foil was actually made of tin, not aluminum as it is today, so I could solder it into the breadboard circuit. For alligator clips I used the springs from old mouse-traps, in order to connect to the coil taps. Soldering was done using pine sap gathered in the spring-time and saved in a small jelly-jar (as rosin solder flux), plus solid solder from Dad’s tool-box. The iron was a plain wood-handle small plumber’s iron heated on a gas two-burner hot-plate in Mother’s basement laundry area. I got a galena chunk from the science teacher’s mineral display board and made a holder for it from thin copper flashing. I got the enameled coil wire from an old electric motor whose bearings had long disappeared. We lived on a farm and did not have household electricity at the time (and wouldn’t get it until 1948) and the motor was a relic from a washing machine from a previous home that did have power. I continued to make and use crystal sets from age 8 until age 12, by which time I had graduated completely to the vacuum tube era, basing the upgrade on the wagon-load of old three-dialers given to me by a nearby “butter, milk, ‘n’ egg” customer of ours when they got lucky and “got on the grid.” Bottom line was that the crystal set needs a very good pair of high-impedance headphones to be effective, except in the Pittsburgh area, where KDKA’s 50,000 watts and hilltop-antenna mast in Allison Park was hearable on crystal sets with even cheap headphones. Of course back in those times there were far fewer sources of AM hash-like noise to compete with AM radio signals than there is today, with all the digital equipment running everywhere."

Robert Lozier shared this: "My location makes crystal set DX no fun. I'm right between two AM stations 0.9 and 1.6 miles away running 4 & 5 kW (and less at night). The last time I checked, both stations only go off-air from Midnight to 6 AM on Mondays. I have several 20s to 50s vintage crystal sets... Plus a few I've built. Maybe my favorite is this Penberthy set. If anyone is interested, Gary Alley loaned me a sales brochure for this set that I was able to restore to make a perfect graphic you can laser print. Here is some commentary I made many years ago.

Ugly but also Elegant - The Penberthy Injector Co. Detroit, Michigan Model 4R - 1925

In early October of 1996, Brad Jones and others organized a one day informal fleamarket for us in Greensboro, NC. After the trading had just about “wound down”, the little crystal set pictured here was still sitting in the back of Ed Bell’s van, dirty, rusty and neglected by just about everyone.... I had found a few small items at the market and was happy I had made the trip with Ron Lawrence and Ted Miller up from the Charlotte area. But !!! I still had way too much money in my pocket and I felt I just had to buy somethin’ more. When Ed told me this dirty, ugly little guy was available for only $20.00, I just could not pass up such a deal !

I did not think much more of my purchase until a day or so later when I decided to see if this set was pictured in Maury Sievers’ two volumes of “Crystal Clear”. Yep, there was a photo (minus the base my set has) but not any more of a description than you see in the title of this article. And that’s all I’ve been able to find out about this set to date.

It was so dirty and rusty I just could not leave it in the shop without giving it a quick clean-up. As I removed the case and inspected the construction, I was immediately taken by the near perfect symmetry of the design and amazed by how so many parts were engineered to provide double duty. Here are some of the things I found to be really elegant....

1. I don’t recall ever seeing moving contacts made by brass rods formed into one-turn spirals as on this set. (I do have a WW-I vintage rheostat that uses this same idea for a moving contact but the one-turn spiral is inlaid into a supporting fiber rod shaft. The leaf springs at the end of the spiral maintain contact pressure and connect the moving contacts to the circuit.

2. The “phone condenser” not only performs the electrical function but also, by making one plate of thick aluminum provides a support hub for the top of the tuning coil. The other plate of the PC is a die stamped part that provides tabs for two of the dual headphone connections. (eliminates wires)

3. The nuts used on the top of the panel each have two V notches cut into them so that phone tips will stay securely attached as well as ordinary stripped wires.

4. The top fl**ge of the tin case provides three of the circuit connections. And the threaded rods that hold the base, which is a cast aluminum part that supports the bottom end of the tuning coil, also mount the PC and are positioned so that the acorn nuts for these rods provide rotational stops for the tuning k***s!
5. There is only one wire in the set necessary to connect to one side of the crystal detector which is mounted in the cartridge on the top of the set. The other crystal connection is made back thru the mounting bracket and thru screws that just happen to connect to the center of the thin plate of the phone condenser..

So, while this little set is still ugly even when its cleaned up, and probably this design is more lossy from a radio frequency energy standpoint than other designs; I am still very much impressed by the absolute elegance of the mechanical design. It just goes to prove that the guts of some of these old sets are just as interesting as the outsides of the cabinets. Think about it the next time you are cleaning up an old set.

Note: At a 1997 meet, Craig Smith pointed out a set of Penberthy headphones he was trying to sell.... He had an instant sale! These phones must have been offered at the same time as the crystal set and show unusual features of their own.

Thank you John, Ed, and Robert for sharing your earlier vintage electronic experiences.

More catchup next week.

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