September 2025

The Superflex

A Publication of the Alabama Historical Radio Society September 2025

NOTE FROM PRESIDENT WAG

Members,

Mark your calendars!

The date for next AHRS Business meeting will fall on the usual 4th Monday, October 27th, 2025, at 7:00 PM. The Exec CMTE will meet in person by invitation only at 6pm.

Join Zoom Meeting
https://us02web.zoom.us/j/86330579924?pwd=ckZLWEJMb0V2ajhBUzh0S2liQnlmZz09

Meeting ID: 863 3057 9924
Passcode: 631140

Everyone should have gotten the news of our treasurer Mike Woodruff’s untimely passing recently. Mike died of complications of heart disease. We express our deepest sympathy to his friend/partner Ann Clarke who is taking care of his affairs, and to family and friends. She expressed a desire to have a celebration of his life at the Society on November 14 at 2:00 PM. All are welcome. Details will be forthcoming. I found his obituary online, a portion of which is copied below:

https://www.dignitymemorial.com/obituaries/pelham-al/michael-woodruff-12524018

Michael received his formal education at Shades Valley High School in Birmingham, Alabama. He furthered his studies at Emory University at Oxford and later at Livingston State College in Livingston, Alabama.

Michael proudly served his country in the United States Army Reserves. Professionally, he worked in banking and insurance as a systems analyst for several organizations throughout his career.

A man of many passions, Michael was a lifelong Ham Radio Operator and had a deep interest in radios and electronics. He also enjoyed participating in the Fuel Exercise class at Vestavia Hills Methodist Church. Michael was an active member of the Alabama Historical Radio Society, where he served as Treasurer, and he delighted in collecting old radios and vintage electronic equipment.

Michael was preceded in death by his father, Richard Woodruff; mother, Gwendolyn Woodruff; and brother, Richard Woodruff.

He leaves to cherish his memory his long-term partner, Ann Clark; his son, John Woodruff; as well as other relatives, dear friends, and members of the radio community who will miss him greatly.

A memorial service will be announced at a later date.

In lieu of flowers, the family requests memorial contributions be made in Michael’s honor to the Alabama Historical Radio Society or a charity of your choice.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Mike was such an integral part of AHRS and will be missed on many levels. As a Society, we must search for a new treasurer, so if anyone is interested in serving in this position, please let one of the officers or board members know. Some knowledge of Quickbooks would be welcome but nothing beyond a willingness to volunteer is required, since the number of monthly transactions we deal with, and other duties, are minimal.

Let me add that our VP and newsletter editor, Steven Westbrook has undergone several tune-ups in recent weeks and is doing well.

Boyd’s next class is Saturday, Oct 4th, 2025, at 9:00 AM in person and via Zoom; he plans to discuss the following:

1. A detailed focus on replacing a totally unknown oscillator coil
2. Demonstration of the NanoVNA in making the necessary measurements in this process
3. Demonstrate a new toy, the 'variable constant current load' for checking wall warts NOTE: Please review the excellent article on wall warts in our last newsletter by Society member Rick Curl.

The following link remains in effect:

Topic: AHRS Radio Restoration Class

Join Zoom Meeting
https://us02web..us/j/88180351990?pwd=N2lucjB3WVhtR05nTSs5S0xGcURadz09

Tom Killian and Ray Giles are looking to host another auction, and this will be announced in advance. In the meantime, we have auction-worthy radios on the table in the shop; if anyone drops in and sees one of interest, consider making a donation and it’ll likely follow you home.

The fully restored Hallicrafters SX-88 is on permanent display on the main level of the shop near the library door. John Green, restorer extraordinaire, completed his 2-part presentation at our September business meeting the other night. Many thanks to him and Boyd Bailey (Zoom facilitator) for making this possible. We plan to have this archived on the website and/or YouTube channel.

Flood (but thankfully not of Biblical proportions!) A few weeks ago, several members working on Saturday noticed water on the floor of the basement storage room under the vault. Items at risk were moved and members on hand vacuumed up gallons of water. Alabama Power came over to dry out the area. A special thanks to Benjy Thomas who did much of the remediation and used his thermal app to identify wet spots; he went outside and noted a water main leak on the Rev Abraham Woods Blvd side of the shop. The leak has apparently been repaired, and we sustained no long-term damage we know of, but will remain vigilant.

Several of our members attended the Gadsden Hamfest and if anyone wishes to comment about their experience, please send it on for inclusion next time.

Save the date! The Montgomery Hamfest (Nov 8^th, 2025, at Alcazar Shrine Temple, 555 East Blvd, Montgomery AL 36117, 8:30 AM-1:00 PM). AHRS is planning to attend! https://w4ap.org/hamfest

And another pair of events: Saturday October 25, 2025 will be the date of the annual Magic City Classic Parade. The staging area and route are around the Shop and overlap our Saturday opening times. Historically, we have NOT opened that day due to the streets being closed and crowds participating; accordingly, the shop will NOTbe open that day.

The Helena (Shelby Co) Tailgate/Hamfest is the same day from 8:00 AM-12:00 PM PM; this is a relatively informal event so check the details on its website. https://www.helenahamfest.com/

We recently received a request for informationfrom Sam Badger, a PhD candidate at the University of South Carolina, who earned his BA and MA from the University of Alabama (“I am Roll Tide for life! “) :

He is interested in recordings and transcriptions of speeches from “…key politicos in 1946, like James Folsom, John Sparkman, Richard Rives, Hugh DuBose, James Simpson, Frank Boykin, Joe Poole, Handy Ellis, et cetera. As far as songs go, I am trying to identify the political undertones in the music that Alabamians were listening to in 1946. For instance, I know two country songs from that year that were very political: "Filipino Baby" by Ernest Tubb and "No Vacancy" by Merle Travis. But I would like to see a DJ setlist or something like that to confirm that these songs were actually played on the radio in Alabama...”

We have given him some contacts and let him know what we have in our library and collections. If any of our members feel you might have something relevant to share with him, let Steven or me know and we can get you in touch with him.

Dave Cisco is working on a presentation about the History of AHRS, including pivotal individuals who are no longer active or with us. Hopefully, this will be available at an upcoming business meeting and become a potential forum for the 2026 BirmingHamfest.

It is getting into flu and other respiratory illness season with many of us being at an age where these could be potentially dangerous. That said, I (wearing my doctor hat) will not enter the vaccine controversies or presume to give medical advice but rather ask you to consult your trusted primary care and/or relevant specialist physician(s) about what you should do this fall, if anything, to help you and yours remain healthy.

Respectfully submitted, enjoying college football, and still looking forward to cooler temps, I remain,

President Wag, AHRS

Magic Eye Tube

A magic eye tube or tuning indicator, in technical literature called an electron-ray indicator tube, is a vacuum tube which gives a visual indication of the amplitude of an electronic signal, such as an audio output, radio-frequency signal strength, or other functions. The magic eye (also called a cat's eye, or tuning eye in North America) is a specific type of such a tube with a circular display similar to the EM34 illustrated. Its first broad application was as a tuning indicator in radio receivers, to give an indication of the relative strength of the received radio signal, to show when a radio station was properly tuned in.

The magic eye tube was the first in a line of development of cathode ray type tuning indicators developed as a cheaper alternative to needle movement meters. It was not until the 1960s that needle meters were made inexpensively enough in Japan to displace indicator tubes. Tuning indicator tubes were used in vacuum tube receivers from around 1936 to 1980, before vacuum tubes were replaced by transistors in radios. An earlier tuning aid which the magic eye replaced was the "tuneon" neon lamp.

History

The magic eye tube (or valve) for tuning radio receivers was invented in 1932 by Allen B. DuMont (who spent most of the 1930s improving the lifetime of cathode ray tubes, and ultimately formed the DuMont Television Network).

The RCA 6E5 from 1935 was the first commercial tube.

The earlier types were end-viewed (EM34), usually with an octal or side-contact base. Later developments featured a smaller side-viewed noval B9A based all-glass type with either a fan type display or a band display (EM84). The end-viewed version had a round cone-shaped fluorescent screen together with the black cap that shielded the red light from the cathode/heater assembly. This design prompted the contemporary advertisers to coin the term magic eye, a term still used.

There was also a sub-miniature version with wire ends (Mullard DM70/DM71, Mazda 1M1/1M3, GEC/Marconi Y25) intended for battery operation, used in one Ever Ready AM/FM battery receiver with push-pull output, as well as a small number of AM/FM mains receivers, which lit the valve from the 6.3 V heater supply via a 220 ohm resistor or from the audio output valve's cathode bias. Some reel-to-reel tape recorders also used the DM70/DM71 to indicate recording level, including a transistorized model with the valve lit from the bias-oscillator voltage.

The function of a magic eye can be achieved with modern semiconductor circuitry and optoelectronic displays. The high voltages (100 volts or more) required by these tubes are no longer in modern devices, so the magic eye tube is obsolete.

Method of Operation

Schematic diagram of a magic eye indicator tube: a = anode, k = cathode, g = grid, b = deflection

A magic eye tube is a miniature cathode ray tube, usually with a built-in triode signal amplifier. It usually glows bright green, (occasionally yellow in some very old types, e.g., EM4) and the glowing ends grow to meet in the middle as the voltage on a control grid increases. It is used in a circuit that drives the grid with a voltage that changes with signal strength; as the tuning knob is turned, the gap in the eye becomes narrowest when a station is tuned in correctly.

Internally, the device is a vacuum tube consisting of two plate electrode assemblies, one creating a triode amplifier and the other a display section consisting of a conical-shaped target anode coated with zinc silicate or similar material. The display section's anode is usually directly connected to the receiver's full positive high tension (HT) voltage, whilst the triode-anode is usually (internally) connected to a control electrode mounted between the cathode and the target-anode, and externally connected to positive HT via a high-value resistor, typically 1 megaohm.

When the receiver is switched on but not tuned to a station, the target-anode glows green due to electrons striking it, with the exception of the area by the internal control-electrode. This electrode is typically 150–200 V negative with respect to the target-anode, repelling electrons from the target in this region, causing a dark sector to appear on the display.

The control-grid of the triode-amplifier section is connected to a point where a negative control voltage dependent on signal strength is available, e.g. the automatic gain control (AGC) line in an AM superheterodyne receiver, or the limiter stage or FM detector in an FM receiver. As a station is tuned in the triode-grid becomes more negative with respect to the common cathode.

Use in Radios

6G5 Magic eye tube

The purpose of magic eye tubes in radio sets is to help with accurate tuning to a station; the tube makes peaks in signal strength more obvious by producing a visual indication, which is better than using the ear alone. The eye is especially useful because the AGC action tends to increase the audio volume of a mistuned station, so the volume varies relatively little as the tuning knob is turned. The tuning eye was driven by the AGC voltage rather than the audio signal.

When, in the early 1950s, FM radio sets were made available on the UK market, there were many different types of magic eye tubes with differing displays, but they all worked the same way. Some had a separate small display to light up indicating a stereo signal on FM.

The British Leak company used an EM84 indicator as a very precise tuning-indicator in their Troughline FM tuner series, by mixing the AGC voltages from the two limiter valve grids at the indicator sensing-grid. By this means accurate tuning was indicated by a fully open sharp shadow, whilst off-tune the indicator produced a partially closed shadow.

Common types

In U.S. made radios, the first type issued was the type 6E5 single pie shaped image, introduced by RCA and used in their 1936 line of radios. Other radio makers used the 6E5 as well until, soon after, the less sensitive type 6G5 was introduced. Also, a type 6AB5 aka 6N5 tube with lower plate voltage was introduced for series filament radios. Type number 6U5 was similar to the 6G5 but had a straight glass envelope. Zenith Radio used a type 6T5 in their 1938 model year radios with "Target tuning" indicator (resembling a camera iris), but was abandoned after a year, with Ken-Rad manufacturing a replacement type. All these types use a 6-pin base with two larger pins for filament connection.

Several other "eye tubes" were introduced in U.S. radios and also used in test equipment and audio gear, including the octal-based types 6AF6GT, 6AD6GT and 1629. The latter was an industrial type with 12 volt filament looking identical to type 6E5. Later U.S. made audio gear used European tubes like EM80 (equivalent to 6BR5), EM81 (6DA5), EM84 (6FG6), EM85 (6DG7) or EM87 (6HU6).

Other applications

Magic eye tubes were used as the recording level indicator for tape recorders (for example in the Echolette [de]), and it is also possible to use them (in a specially adapted circuit) as a means of rough frequency comparison as a simpler alternative to Lissajous figures.

A magic eye tube acts as an inexpensive uncalibrated (and not necessarily linear) voltage indicator, and can be used wherever an indication of voltage is needed, saving the cost of a more accurate calibrated meter.

At least one design of capacitance bridge uses this type of tube to indicate that the bridge is balanced.

The magic eye tube appears on the cover of My Morning Jacket's 2011 album Circuital. The tube is shown almost fully lit.

-Wikepedia

Quotes of the Month

“I did turn 75 today - but remember that is only 24 Celsius.)

- Ronald Reagan

“Reality is just a crutch for people who can not cope with drugs.”

- Robin Williams

“We owe a lot to Tesla – If if wasn’t for him we would be watching television by candlelight.

- Milton Berle

We meet every Saturday (unless a Holiday weekend) at 8:30 A.M. until around 11:30 A.M., at the one-story AHRS Shop at the corner of 8th Avenue North and 18th Street, (1801 8th Avenue North, Birmingham, AL 35203). Please use the rear (Southeast) entrance.

The Shop is open on Tuesdays at 8:30 A.M. until around 11:30 A.M. Note that parking can be a problem on Tuesdays, so you may have to find street parking occasionally.

Regular monthly members meetings are on the fourth Monday night starting at 7:00 PM with the Executive Meeting starting at 6:30 PM

Please come join us!

The electronics classes are generally on “Zoom” and “in-person” at the AHRS Shop, typically the first Saturday of each month (except when something special is taking place, then we agree on an alternative Saturday)

Check your emails for the schedule and how to participate.

We start from the beginning Ohms Law, inductors, resistor and Capacitors color codes, as well as what each component does within the radio circuits. We also teach how to use test equipment used in the repairing of radios. We teach troubleshooting radio troubles, as well as how to read a radio diagram.

Currently the class is studying advance topics relating to troubleshooting and project radio repair. We are retooling our website in hopes of archiving prior classes for those who may have missed a prior class. Email will provide timely details on date, topics & links.

There are coil winding classes, and one-on-one repair help. Come join these classes!

Membership dues are $25.00 a year, payable beginning in January. If you have questions about your dues, you can contact Treasurer Mike Woodruff at 205-823-7204. Dues can be mailed to AHRS at P.O. Box 131418, Birmingham, Alabama 35213 or paid on-line at https://alhrs.org

Be sure and check out our website at https://alhrs.org, which has copies of all newsletters from 2006 to the present (click on News), videos, photo galleries, museum, Old Time Radio columns, Projects, Reading Rooms, Archives, and Contact Information. Within the next few months we hope to update our website and add additional content and new capabilities

President – Richard “Wag” Waguespack

(205) 531-9528

drminims@aol.com

Vice President – Steven Westbrook

(205) 305-0679

spwestbro@bellsouth.net

Recording Secretary – Grady Shook

(205) 281-3007

gshook@bellsouth.net

Treasurer – Mike Woodruff

(205) 823-7204

woodruff_michael@hotmail.com