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Articles of General Interest

How to Drive to Ottawa Might seem simple, but I can make anything complex.

The All-American 5: Radio for the Masses. This article is about the most common AM radio in the 1940's '50's and '60's, found in every North American home.

The HP428 DC clamp-on ammeter. This article describes a fascinating instrument: HP's "flux gate" clamp-on DC ammeter.

The Birth of a Radio Man This is my brief autobiography!

Book Review: Boys First Book of Radio and Electronics

Crossword Crossword Clues This is a crossword for tube lovers. Rather than words, it uses tube numbers. Solution

Early Telegraph in Canada An overview prepared to mark 150 years of telegraph in Canada.

WLW_1935 The fight between CFRB and WLW

The Clairtone Mini HiFi A last attempt at survival for an iconic Canadian company

The Phantastron This wonderfully-named circuit generates sawtooth waves. It is complex and elegant at the same time!

Repairing a Cast Iron Radiator You can't let radiators freeze. Here's how you can fix a leaky one.

Estimating the Resonant Frequency of an Inductor. Did you know that the parallel resonant frequency of an inductor can be estimated using nothing more than its value?

Gord's Projects

Construction Projects

FM converter This device can be installed into a standard 5-tube "All American Five" radio to convert it to FM operation.

Eye-Tube Converter: use a 1629 as a 6X6 or 6U5 magic eye

A solid-state version of a magic eye A circular array of LEDs and a bar-graph display chip make this realistic 6U5 6E5 6X6 1629 replacement.

High-Performance Crystal Radio The name says it all. Coauthor Don Asquin. Here is another version from the OVRC bulletin

Cardboard Box Crystal Set This crystal radio features hand-built inductor and hand-built variable capacitor.

Philco Farm Radio and Power Supply

10MHz frequency reference disciplined to CHU Since I live in Ottawa, CHU at 3.33MHz is a strong signal. This project locks a 10MHz crystal reference to CHU. This is not well documented, but I have some rough schematic diagrams here: TopLevel_FrontEnd IF_Filter PLL_Monitors Output_Buffer_Filter VCXO

Power supply for portable tube radios  Portable radios need large batteries. This supply allows you to use a USB charger instead.

Superregen FM Receiver,  all-tube design that runs from 24VAC with room-filling volume 

One Tube CHU time signal radio  I was challenged to build a 1-tube radio. This one uses a triode + pentode in a reflex circuit to receive CHU time signals at 3.33MHz.

A simple ESR meter The Equivalent Series Resistance is an important characteristic of an electrolytic capacitor. This very simple and robust meter does this measurement in a very unusual way. Updated article

The best way to check if a filter capacitor is dead is to put one in parallel with it and see if the hum is reduced. This little box makes that safe and easy FilterCapBox

Replacing the display on a Marconi 2030 / IFR 2030 / Aeroflex 2030 synthesizer . This board allows the synth to drive a NTSC monitor. It was designed in KiCad, and the project archive is here. 

L-C meter project (works with your DVM) for chokes and electrolytic capacitors LCMeter

A Radio Demonstration Board based on a 1936 GE superhet DemoBoard

An experimental AM transmitter Transmitter

A continuity tester probe, for tracing out wires. low voltage and low current, but a 15 ohm threshold.  Continuity Probe

Repair Articles

Repairing an AA5 radio: A general approach for radio repair.

Repairing a French Ducretet Radio

Repairing a haunted Philco Model 70 radio I fixed up this radio, but then a ghost moved it.

Sony TR72 Radio I fixed up a very early transistor radio, the Sony TR72

Early Stromberg-Carlson AM-FM radio

Repairing a Stewart-Warner King

Repairing a Stewart-Warner Schubert

Oscillation in Vintage Radios

Using AVC as a service tool 

How To

How to align a radio: For superheterodyne radios, like the AA5.

Filament Resistors: How to replace a filament resistor with a capacitor.

This nomograph makes it easy to calculate the required capacitor value. Draw a straight line (with a ruler) from the total filament voltage, thru the filament current, to the "Cap" axis, and read off the required capacitor value. In the example shown by the dotted line, 69 volts is required for the filaments, at a current of 0.3 amps, and the required capacitor value is about 8.1uF. The math that produced this graph is exact, and assumes a 120V 60Hz mains supply.

Chokes: How they behave, how to measure them Choke inductance vs. DC current, vs. AC current, and a really simple choke meter.

And, related to the chokes project, this describes a L-C meter project (works with your DVM) for chokes and electrolytic capacitors LCMeter

Estimating the Resonant Frequency of an Inductor. Did you know that the parallel resonant frequency of an inductor can be estimated using nothing more than its value?

All About Capacitors

All About Resistors  (solution to the resistor challenge is here)

Exact calculation for a 4-element matching network. Description Spreadsheet

Gord's Favorite Links

Ottawa Vintage Radio Club Website OVRC

Ottawa Vintage Radio Club YouTube Channel OVRC_YouTube

Frank's Electron Tube Data Archive TubeData

There are plenty more at OVRC_Links