May 2024
NOTE FROM PRESIDENT WAG
Members,
Remember our next monthly business meetingat the Shop and via Zoom is scheduled for Monday, June 3, 2024, as usual at 7:00 PM; The date was moved to avoid conflicting with Memorial Day. Thereafter, we will revert to our usual schedule of the 4th Monday of each month: The following meeting is June 24th. The link remains:
Join Zoom Meeting
https://us02web.zoom.us/j/86330579924?pwd=ckZLWEJMb0V2ajhBUzh0S2liQnlmZz09
Meeting ID: 863 3057 9924
Passcode: 631140
We continue to monitor for internet outages at the Shop; hopefully, this has been corrected remotely.
The newly created Executive Committeewill meet for the second time prior to the upcoming monthly business. It is functioning as planned between formal meetings, although still in diapers. (Please do not let that image form in your minds!)
Boyd Bailey’selectronics class was held on Saturday, May 4th at 9:00 AM and covered resources offered by the California Historical Radio Society. It should soon be available online [Google Drive] for those who might have missed it. The next class scheduled for June 1st must be postponed to a later date.
Details of this next offering will be:
1. Fundamentals
will be sent soon. Do not forget Boyd’s chronological and comprehensive listing [AHRS Radio Restoration Classes Mar 2020 thru Mar 2024.pdf] of his courses during the past 4 years. A copy is attached to the cover email for this newsletter.
Ron Studdard, member and class regular, sent the following additional information via email and I thought we would share it with the membership at large. Thanks Ron!
1931 Airline Console - details following a schematic
https://youtube.com/playlist?list=PLPagKqeCjne9F9i21nCl_vQCGE00WEcHV&si=xOrnzyUY0utWwt9q
Our next auction has been scheduled for Saturday the 15th with thanks to Ray, Tom, and the team checking and cleaning items. We will send the auction catalog and details soon.
The museum cabinets in the Alabama Power atrium that required rewiring have been largely refurbished. We will be working on conserving our exhibit items and attendant documentation in the coming months. Dee Haynes, Grady Shook, Barron Smith and Steven Westbrook have been working on the project.
The BirmingHAMfest showcased members Russ McGuire and Dave Cisco who presented a forum on their love of, and accomplishments in, amateur radio DX-ing. The talk was presented in Tuscaloosa and likely soon in Gadsden to their respective amateur radio clubs.
The Huntsville Hamfest is approaching, and we plan to be there on Saturday, August 17th, 2024. We surely can use volunteers to help select items and man the tables. Please let us know if you can help! We really need assists from those with ham experience to help select items of potential interest to attendees.
A delegation from the Society went to the Dayton Hamvention in Xenia, Ohio in mid-May. It was a fine trip, although it rained the opening morning (below left photo) and sizzling on Saturday. We purchased antique books from AWA (Antique Wireless Association) focusing on the first two decades of the 20th Century. Jim Kreuzer (AWA Librarian and Assistant Curator) and his wife Felicia had pre-selected some outstanding ones from which we chose. We will provide details in the next newsletter. A special thanks to member Robert Cain & Dave Cisco, who donated funds to help with the purchase.
John Green, an old friend and high school classmate of Dave Cisco and John Outland now living in North Carolina, found and donated a Radiola X to the Society, one of the oldest RCA radios.
As is traditional, our group attended the DX banquet on Friday evening; see the photo in our bonus section. Our final evening dinner at a restaurant in our Waynesville Ohio home base was shared with other AHRS & BARC attendees from Birmingham.
One of the grants to which we applied is supported by CAWACO RC&D (Alabama Association of Resource Conservation & Development Councils). The process is ongoing, and we hope to finalize and hear about an award this summer.
In closing, I took another trip early this month to the London area, co-sponsored by the National World War II Museum in New Orleans and the International Spy Museum in DC. It was outstanding and focused on espionage during WWII, especially signals intelligence and codebreaking. That is a potential subject for another time but historical radios that went to the UK from the States via the Lend-Lease program prior to our entering the war [eg, HROs and RCA AR-88s] played a key role. We visited Bletchley Park, key to codebreaking German radio traffic, which also hosts the National Radio Centre sponsored by the Radio Society of Great Britain (RSGB) that parallels the ARRL’s mission. RSGB had a booth at Dayton that was well staffed and visited, including me.
Respectfully submitted,
Wag
President, AHRS
drminims@aol.com
And now, a special bonus, the 1stinstallment of Dave Cisco’s authorized biography. The facts were provided by Dave and scripted by Wag. More to come!
It began on a dark and stormy night in December 1938, in Indianapolis, Ohio or perhaps it was just a perfect day. Board chairman Dave Cisco was born there, and he soon moved south when his dad was transferred to Decatur Georgia. A 4th grade teacher sparked his interest in radio and when his dad was again transferred to Birmingham, he began to learn code and radio theory at Ack Radio. (They lived in a section known as Edgewood in the suburb of Homewood, not far from his close friends and later co-Society members: John Outland, John Green and Ed Boutwell) Dave, ever the prodigy, took his novice exam at the post office in Birmingham in June and, by August 1953, was a novice with the call sign WN4AXL. The next year he obtained his technician license as W4AXL and joined BARC (Birmingham Amateur Radio Club); his first hamfest was the same year in 1954 was at the Roebuck Country Club.
By the time he started the Shades Valley Amateur Radio Club, he had attained his general ticket. Upon graduating from Shades Valley High in 1957, he worked at WEZB Radio. (Your humble author at this time was in the 3rd grade in Harahan Elementary, a suburb of New Orleans, and was more interested in afternoon and Saturday morning TV shows…)
Flash forward to 1987 when he assisted Don Kresge (who died in 1993) founded the Alabama Historical Radio Society (AHRS). Dave has served as president and has been on the board for about 35 years, now serving as its chairman. He has been instrumental in documenting radio history in Alabama, which includes interviewing many of the people involved directly, and indirectly, in early radio; we have a number of these oral histories available in our archives. In addition to helping secure many of our display and Museum items, he has functioned as our librarian for years.
As recently as this month, Dave journeyed to the Dayton Hamvention (the largest Hamfest in the world) and secured additional books for our library, focusing on the first two decades of the 20thCentury. His interest in amateur radio is largely unabated: He was again recognized as one of the elite DX-ers in the US with only a handful or two of others at the annual DX banquet logging more country contacts than he.
One cannot overestimate the role that Dave has played in the evolution of AHRS and he has been helping to formulate and implement its strategic goals as a meaningful historical society for decades now.
Tune in for the next installment when we focus on Dave’s work history and other interests!
Attendees at the May 2024 Southwest Ohio DX Association (SWODXA) Dinner at the Dayton Hamfest
Submitted by a Society member:
Spend an Hour in the Virtual Radio Museum
By Al Williams
If you have an hour to kill and like old communication technology? If you happen to be in Windsor, Connecticutt, you should trip over to the Vintage Radio and Communication Museum. If you are not in Windsoe, you could watch {WG7D’s} video tour.
The museum is a volunteer organixation and is mostly about radio, although we did spy some old cameras if you like that sort of thing. There was also a beautiful player piano that – no kidding- runs from a vacuum cleaner.
One notable piece of gear was an old tube tester of the sort you used in pharmacies, and the guide memtioned that they have 100,000 tubes in storage. If you are ham radio operator, you will appreciate the vintage code gear and teletypes. The amount of old gear here is impressive, including unusual record players, movie theater projectors, and lots more.
The guides are clearly not used to having someone like [WG7D] in the museum as they explained things like Moris code and magic eye tubes. If you happen to be in the area, we are sure a real tour would be better than the video, but we did enjoy the virtual visit too.
If you are planning a museum trip, do not miss the Obsolete Technology Museum or the Large Scale Systems Museum.
Posted in Misc HacksTagged museums, vintage electronics
The link is https://www.youtube.com/watch?v=8tjK911QkII&t=3923s The clickable link is on the email to which this newsletter was attached.
Here are a few highlights and some other notes of interest we received from antique parts supplier Radio Daze
First, A Radio Daze Thank You Promotion!
As one method of thanking our customers for their loyalty and support for over 33 years, customers who place orders for items totaling over fifty dollars will automatically receive a free copy of E.H. Scott: The Dean of DX in their shopping cart and order!
More about this book follows:
E.H. Scott – The Dean of DX
During 2001-2002, Radio Daze had the distinct privilege of working with Marvin Hobbs on a greatly expanded version of his 1985 book E.H. Scott: The Dean of DX – A History of Classic Radios. Marvin was Chief Engineer of Scott Radio Laboratories from 1939-1947 during the development of significant advances in radio and communications technology before, during and after World War II. With a B.S.E.E. and Ph.D. in Engineering Management, Marvin also worked at Zenith Radio, Delco Radio, E.K. Cole, RCA and Bell Telephone.
Published in 2002 by Radio Daze, the 256-page second edition of E.H Scott: The Dean of DX provides first-person recollections and insights by Hobbs into the vision of one man, E.H. Scott and his company that continually set the highest standards for radio receiver technical performance, innovation, and quality. A most unique and interesting insight into a fascinating piece of the history of radio.
Dial Cord Is Back
Radio Daze has restocked its dial cord which we offer in two different diameters. For most applications, the typical dial cord diameter is around .030-.032 inches (0.8 millimeters). We also offer a slightly heavier version at .039-inch diameter (1.0 millimeters) which is appropriate for some tougher duty applications.
We have noticed the insanity of some of the pricing for dial cord on outlets such a eBay, etc. An example is 12 feet of dial cord for $9.75 or 25 feet of dial cord for $12.75. Our dial cord is sold in 25-foot lengths at $4.99 or $5.99 depending on diameter!
Take Me to the Radio Daze Dial Cord!
Mounting Dial Glass – Protective Rubber
In many applications, dial glass is traditionally mounted with some padding material for protection between the dial mounting hardware and the glass. This material has typically been a paper/cloth fiber or a form of rubber, all of which usually deteriorate with age. Radio Daze offers quality rubber U-channel extrusion for these applications designed specifically for the two common nominal thicknesses of glass dials, i.e. 3/32 (.093) inches and 1/8 (.125) inches. Keep this in mind when you are restoring a vintage set to its original glory!
Take Me to the Radio Daze Dial Glass Mounting Rubber!
Potentiometers – Still On Sale
All of our stock of new production single and double section potentiometers remain on sale. These are standard 1/4" diameter solid aluminum shaft, 3/8" bushing potentiometers with solder tabs. On sale while quantities last.
Take Me to the Radio Daze Potentiometers!
A Grille Cloth Update
We continue to support and expand our grille cloth offerings. Since our last update we have restocked our very popular GRC-92 generic crisscross pattern. In response to some requests, we also added a new generic pattern, our GRC-93, which is a chevron “V” pattern with the V width at 22 inches. Please note that while many are asking for this pattern, it is not the 25-inch-wide pattern needed for a handful of Philco sets.
Take Me to the Radio Daze Grille Cloth!
Reproduction Graphics – New Design Releases
While our efforts are very heavily focused on filling customer orders as soon as possible, we also have a small design team working to address limited new requests for reproduction graphics items. Many of our customers have asked us to post a list of new reproduction graphics designs when we update news from Radio Daze. To that end, here are the new items recently released:
Drake L7 Amplifier Meter Face Set (Item: DS-A903)
Drake TR-4 Enclosure Decal Set (Item: DCL-DRAKE-TR-4C)
Farnsworth ET-066 Dial (Item: DG-563)
Firestone Model S-7398-8 Decal Set (Item: DCL-FR-S-7398-8)
Johnson Courier Meter Face (Item: DS-A898)
McIntosh Model MR67 Dial Glass-NO LOGO (Item: DG-322Z)
Philco P-4735 Auto Radio Dial (Packard) (Item: DG-564)
RCA CR-88A Meter Cover (Item: FP-RC-CR88A-MCOVER)
RCA Model 810K, 810K1 and 810T Side Indicators (Item: DS-A899)
RCA TRK-5 TV Decal set (Item: DCL-RC-TRK-5)
Sonora TJ-62 Dial (Item: DS-A902)
Sparton 6-26 Dial (Item: DG-562)
A Sincere Thank You To All Our Great Customers!
Quote of the Month
“If God had not intended for us to eat animals then why did he make them out of meat?”
-John Clease
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
Boyd Bailey, Member and Instructor
(334) 412-6996
boyd.bailey@charter.net
Newsletter Editor/Webmaster – Steven Westbrook
(205) 305-0679
spwestbro@bellsouth.net
Web Address:
https://alhrs.org
E-mail Address:
ahrs2000@gmail.com
Youtube Channel:Alabama Historical Radio Society - YouTube
Attachment to Newsletter:
Alabama Historical Radio Society Radio Restoration Classes
March 2020 through March 2024
- 3/14/2020
a. Inductors
b. Phase dot convention
c. Kirchoff’s two laws and Ohm’s law
d. Voltage and Current Divider (DC)
e. Voltage Divider (AC) - 5/2/2020
a. Wrap-up of points from 3/20/20
b. Overview of schematics from 3 books: Elements of Radio Servicing (Marcus); Vacuum
Tube Shortwave Radio (McWhorter); The AA5 – Understanding and Restoring
(McWhorter) - 5/30/2020
a. Vacuum tube rectification and power supply basics
b. Groundwork for VT as a ‘voltage divider’ - 6/13/2020
a. Review diode tube rectification
b. More on voltage divider
c. Vacuum tube biasing
d. Introduction to IP - EG tube characteristic curves
e. Triode examples
f. Introduction to the pentode and pentagrid - 6/27/2020
a. Triode signal phase in and out
b. More on IP – EG VT curve characteristics
c. Plate Current vs. Grid Voltage vs. Plate Voltage (dynamic transfer characteristic)
d. Regenerative Receiver
e. Pentode and pentagrid VT details - 7/25/2020
a. Analyzing a schematic for tests points for oscilloscope or DMM
b. Troubleshooting groundwork
c. Signal injection
d. Grounding concepts
e. Practical demo of AVC feedback - 8/29/2020
a. Heterodyne signal path with test-points
b. Commercial Band Tracking adjustment
i. Osc trimmer, 600 padder
c. Master VT simplification ***
d. Graphical illustration of grid electron cloud causing resistance
e. More on pentode and pentagrid - 9/19/2020
a. Signal path review
b. Motorola C39 clock radio
pg. 2
c. Zenith 8T01 (class project 2019)
d. More on band matching
e. Transformer Impedance matching
i. LCR method
ii. Joe Minor illustration
f. Transmission Line Impedance
9. 10/10/2020
a. Triode Vacuum Tube basics (McWhorter Illustrations)
b. Pentagrid (2-triode alternative view)
c. Understanding the local oscillator mixer converter circuit (using the RCA 8Q2 model)
d. Mixer Converter Circuit ROAD
10. 12/5/2020
a. Project – Westinghouse H-382T
b. Schematic with all points of repair
c. Grounding concept
d. Couplate replacement or equivalency
e. Oscillator coil matching
f. Miller 69-osc vs. P-C70-osc
g. Phase dot review
h. Silver mica disease
i. Output transformer impedance characteristics and matching VT impedance
j. Datasheet load impedance
k. Matching osc coil to tuning capacitor circuit
l. Oscillator Coil – more points
11. 1/9/2021
a. What I learned matching Osc Coil to tunning capacitor circuit
b. More points on Osc Coil
c. Output transformer impedance matching
d. Output stage VT (amplifier); 50C5 datasheet
12. 2/6/2021
a. Photos of Westinghouse 382 project
b. Project review, RCA 1050
i. Restoration with puzzling hum
ii. Hum troubleshooting
- Power supply filter capacitors
- Cathode to filament leakage
- Multiple sources
c. Hum-bucking coil
d. Low pass filter (passive) RC
e. High pass filter) passive) RC
f. Tau (τ), time constant; charging and discharging circuit
g. Diode detector (low pass)
13. 3/13/2021
a. Philco 60, ca. 1935
b. Antenna and oscillator coils
c. Philco Bakelite “Condensers”, cleaning and repacking
d. Magnetic speaker replacement
e. Build a non-magnetic socket driver for aligning vintage Philcos
pg. 3
f. Cleaning tools
g. Band pass filter
h. Dog-bone resistors
14. 3/27/2021
a. Philco 70, ca 1931, restoration project
b. Identified problems
c. Potential bias related distortion in 1st AF stage
d. Organizing the schematic prior to analyzing
e. Incomplete or wrong data
f. Signal tracing with a scope
g. Alignment basics
h. Demonstrate distortion problem
15. 5/1/2021
a. Philco 70 (cont’d)
b. Resolution of distortion problem
c. Review of sine wave signal through radio
d. IP - EG curve
e. Illustrate inverse relationship of Load Resistance (RL) to Plate Current (IP)
f. Illustration of plate characteristics curve
g. Tube 47 VCG vs VP with 7,000 Ω ‘sweet spot’
h. Output transformer impedance matching
i. Preview Simpson 260
16. 6/5/2021
a. Wrap-up Philco 60 with new cap failure
b. Simpson 260 family (Series 1 – 8)
c. Fundamental 260 circuit
d. Breaking down the schematic
e. Meter is an ammeter 50 μA at 5000 Ω, provides 50 μA at 250 mVDC
f. My 250 mV ‘work-around’ voltage source
g. Calibration demo
h. Connectors
17. 7/17/2021
a. Zenith 5-R-216, ca 1938, restoration
b. Identified problems
c. Main task of sizing and replacing the power transformer
d. Transformer basics and magic of reflected impedance
e. More on output transformer replacement
18. 8/4/2021
a. Simplifying a circuit with respect to the power supply
b. Zenith 96-441 transformer with simplified circuit load
19. 9/11/21
a. Farnsworth BT-600
b. Identified problems
c. Vacuum Tube review
d. Biasing review
e. Overview of Barbarosa Beer Bottle Radio
f. Setting up schematic to start trouble-shooting
pg. 4
- 10/9/2021
a. Wrap up Bottle Radio
i. Volume potentiometer replacement
ii. Speaker voice coil and cone replacement
b. Atwater Kent Radios
c. Overview of Tuned Radio Frequency (TRF) radios
d. AK 35 schematic review
e. ARBE-III battery eliminator
f. Repair steps on the AK 35 and demo - 11/6/2021
a. Wrap up on 1st AK 35
b. Challenges on 2nd AK 35
c. Scratch-built copper belts
d. 3
rd Atwater Kent – AK 30
e. Homemade battery eliminator ideas - 12/4/2021
a. Battery Eliminator
b. Isolation transformer examples
c. LM-317 voltage regulator
d. Hammond 229 Series BE-3 kit
e. 90 v B+ only, examples - 1/15/2022
a. Basics of the RLC circuit review
b. Basics of air coil inductor equations
c. Crystal radio fundamental schematics
d. Inductive coupled antennas
e. Typical Xtal radio schematics
f. How about a TRF crystal radio set? - 2/14/2022
a. Transistor
b. Basics of the Bipolar Junction (BJT)
c. Review VT basics to contrast with transistor
d. Biasing
e. Transistor configuration
f. Four (4) Rules of transistors
g. IP – VP (tube) compared to IC – VCE (transistor)
h. Water analogies
i. Transistor biasing schematics/configurations - 3/7/2022
a. SMD markings
b. Demo surface mount de-soldering and soldering
c. Start Super Probe project
d. Demo cable-tracer probe
e. Demo transistor curve tracer - 4/2/2022
a. Philco 41-290, ca 1941, restoration
b. Introducing “The Vacuum Tube Shortwave Radio” book
pg. 5
5/7/2022
a. Airline (Montgomery Ward) 62-256 parallel to the RCA8Q2
b. Safety basics review, emphasis on ground
c. Chapter 1, VTSWR book
6/11/2022
a. Review of topic details list from 3/2020 thru 5/2022
b. Review and unpacking of MacWhorter’s VTSR book, Chapters 2 and 3
c. Class member project updates
7/11/2022
a. Exploring Chapter’s 4 and 5 of McWhorter’s VTSWR book
b. Drilling down in the RCA 8Q2 schematic
c. Fixed biasing vs cathode (self) biasing
d. Update on class member’s Zenith 10MT26 console unit, specifically cap polarity and
schematic symbols
8/6/2022
a. Chapter 6 of McWhorter’s VTSWR book, walk-through
b. Illustrate the AVC and tuning eye (6E5) in the Airline (MW) 62-256
c. Walk through the principles of the negative AVC and tuning eye (6E5)
d. First and second IF transformers; calculations for 455 kHz
e. Walk through the 455 ‘drainage’ points
f. Clarification of 3 setting of ‘tone control’ in the RCA 8Q2 from previous meeting
9/17/2022
a. Chapter 7 of McWhorter’s VTSWR book, walk-through
b. Simplification of the schematic into the basic ‘oscillator’ circuit
c. Electron fluctuations in a RLC “Tank Circuit”
d. Rough calculations to estimate oscillator coil inductance to match the tuning capacitor
(Antenna plus oscillator sections)
e. Mixer Converter
f. Principles of heterodyning
g. Demonstrate the oscillator function of injecting the 455 kHz IF by signal generator and
spectrum analyzer
h. Demonstrate IF transformer tuning to 455 kHz
10/1/2022
a. Chapter 8 of McWhorter’s VTSWR book, walk-through
b. Why have an RF amplifier stage?
c. Antenna tuning coils
d. Component function review from the chapter
11/5/2022
a. Chapter 9 of McWhorter’s VTSWR book, walk-through
b. Highlights of chapter
c. Wafer switch complexity review
d. Identifying ‘test points’ on the RCA 8Q2 schematic
e. Walk through the Zenith 6D311, an easier (and more common) schematic type to set
TPs
f. Demo with the 6D311
pg. 6
- 12/3/2022
a. Chapter 10 of McWhorter’s VTSWR book, walk-through
b. Review of mica capacitors (‘domino type’) and resistors (‘dog bone types’) color and
code systems
c. Power transformer basics review
d. Parts examples from salvages and discussion - 1/7/2023
a. Chapter 11 of McWhorter’s VTSWR book, walk-through
b. Safety basics; grounding review
c. Band tracking and IF alignment
d. Practical alignment using the Airline (Montgomery Ward) 62-256
e. Using a PLL radio to test oscillator function - 2/4/2023
a. Chapter 12, first half, of McWhorter’s VTSWR book, walk-through
b. Unpacking the sections; current is main focus - 3/11/2023
a. Chapter 12, second half, of McWhorter’s VTSWR book, walk-through
b. Adding a high-wattage resistor to decrease operating voltage
c. Show & tell for signal tracers and injection points
d. Demonstrate simulated modulated signals with sig generator and tracer - 4/1/2023
a. Explore the shop’s Fabri-Tek Radio Demonstrator
b. Demo board has a malfunctioning oscillator coil
c. Matching an oscillator coil (see also AHRS WS 12/5/20 and 1/9/21)
d. Demo board calculations for oscillator coil, plus ball-park estimations
e. Matching the variable capacitor and oscillator coil using resonant frequency formula - 5/6/2023
a. Trouble shooting basics on the Fabri-Tek Demo Board
b. Antenna basics
c. Using the Nano-VNA to measure ‘reflective loss’ in an antenna; use to ID what bands are
closest or best covered in a loop antenna
d. Using the Tiny SA (Spectrum Analyzer) for analyzing the oscillator circuit (determine if
working - 6/3/2023
a. FM Basics: making the leap from AM heterodyning, or side bands, to FM side bands and
information patterns
b. SDR demonstration
c. Comparison of AM and FM receivers
d. RF stage basics
e. FM converter system
f. Groundwork for further downstream circuitry (Limiter and detector) - 7/8/2023
a. Review of FM related terms and mor basics
b. Limiter concept
c. Types of FM demodulators
d. Vintage FM antenna basics
pg. 7
- 8/12/2023
a. FM alignment basics
b. Meter method vs. visual method
c. Discriminator transformer
i. Primary maximized
ii. Secondary zeroed
d. Sequence: 3rd IF, the 2nd, etc
e. Aligning the RF end of the receiver
f. Variation for test points between Foster-Seeley and Ratio Detector discriminator circuits - 9/9/2023
a. Voltage dropping; Replacing defective resistance line cords and ballast tubes
b. Voltage dropper approaches and calculations
c. Focus on capacitive dropper
d. Ron’s RCA 114 with ‘resistance cord’
e. Bailey’s Zenith 6D311 with ‘ballast tube’ - 10/7/2023
a. General online resources; how to find, how to maneuver.
b. Useful links for restoration and repair
i. Our own excellent site: alhrs.org
ii. Useful sites in addition to alhrs.org
c. Finding schematics
i. Riders – Beitman
ii. Sam’s Photofacts - https://theschematicman.com/
- https://library.austintexas.gov/virtual/sams-photofact-online
- Best and only ‘free’ source is the AHRS paper bookshelf!
d. Highlights of thumb drive material
45. 11/4/2023
a. All about capacitors
b. Systematic steps in analyzing caps
c. Understanding internal series resistance (ESR) and leakage (EPR); A. Wolke (W2AEW
YouTube)
d. Caps simplified and explained; (Blueglow Electronics, YouTube)
46. 12/2/2023
a. Unpacking Gord Rabjohn’s “Capacitors in Your Old Radios”
b. Misc capacitor technology
c. Mica and ceramic codes
47. 1/6/24
a. "Capacitors in their element" section of Rabjohn's "Capacitors in Your Old Radios". Cool
stuff related to trouble-shooting capacitors in different functional elements of the radio
circuit.
b. Demonstration of analyzing 'leakage' and 'high voltage breakdown' using a Sprague Tel-
Ohmike TO-6 capacitor analyzer.
c. 3. Wrap-up thoughts on capacitors.
pg. 8
d. Introduction to some basics of diodes/LEDs, in anticipation of a full session on replacing
incandescent bulbs with LEDs in vintage equipment next session?
- 2/3/2024
a. Fundamentals of the ‘diode’ (PN junction and Zener) as a prelude to understanding the
LED.
b. Putting it all together; the basic schematic
i. Resistor to control voltage drop and current
ii. Diode to rectify sine wave to half wave
iii. Zener to protect LED
c. Vintage radio pane light replacement examples
d. Circuitry breadboard demo - 3/2/2024
a. Tube testers, types, and how they work
b. Basic ‘emission’ principles
c. Advanced emission
d. Transconductance / Mutual conductance
e. Emission vs conductance
f. Other tests for vacuum tubes – shorts, gas, cathode leakage, open element, curve
tracing