Richardson "5" - 1925

I recently purchased a Richardson "5" TRF receiver and after bringing it home discovered somewhat disappointingly that, although in excellent condition appearance-wise, this radio is not going to play without a significant amount of work.

Although it was sold to me with the opinion that it did play, I think it more likely that it played at some point in the past ... although I'm willing to give the seller the benefit of the doubt.

The Richardson Radio Inc of New York seems to have appeared on the scene in 1925, lasting perhaps a year and then vanishing. The Richardson "5" features neutralization but doesn't appear to mention licencing that technology from Hazeltine so this may have had something to do with their short life.

The chief problem seems to be the wiring which is soldered in only a few places and otherwise consists of stakes or posts that have been pushed through the insulation of the wires in the same way that inexpensive garden lights are sometimes put together.

Given time, almost 90 years in this case, the poor contacts and gradually deteriorating insulation have done a good job in turning almost every connection into an intermittent connection. When I powered the radio up it was obvious that the two stages of audio amplification were working but touching any wire in the RF amplifier or detector sections just changed the quality of the noise in the headphones. I was never able to tune in a station or even see if the RF sections were working.

So, I have a choice. This radio can either be dust collector on the shelf and an example of how not to wire a set or I could re-wire it using proper soldered connectors which wouldn't be "authentic".

Not sure what to do exactly. Not that I will be diving into it any time soon, I still have the AK20 restoration to complete before I start anything else.

It didn't come with a speaker but I didn't find any evidence that Richardson Radio ever sold a loud speaker and the example at the top of the page uses a "Superspeaker Console" from the Jewett Radio & Phonograph Co.

The Richardson "5" uses a six volt "A" battery and "B" battery voltages of forty five and ninety volts. When running from the ARBE III supply I set the "A" battery voltage to five volts so there is little risk of burning the five 01A tubes too brightly.

All-in-all I would say that it is a handsome set that will look good on the shelf and may eventually be made to work again. It will be interesting to see what difference the neutralization makes to a circuit that is essentially identical to the AK20.

Atwater Kent - Model 20 : Important Documents

One of the first things I do once I have acquired a new "treasure" is to gather together all the information I can find and stick it in one place.

To this end, here is what I have found online and scans of some of the paperwork I have acquired. Most will be specific to the Model 20 but some may also cover other Atwater Kent radios:

Sadly I do not have a high resolution scan of the Model 20 log card which I believe is Form F 103, can you help?

This is Form F 194 which would suit a single dial Atwater Kent radio.

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

A small amount of cleanup may be required to print correctly on your printer.

Download the PNG file HERE (49MB)

At the right is the "Radio Log Cards and Important Instructions" envelope which was used to organize all the paperwork. This would typically be held in between the two clips inside the radio.

If you are wondering what those clips were used for, now you know!

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

A small amount of cleanup may be required to print correctly on your printer.

Download the PNG file HERE (57MB)

This is the back of the envelope so you can see the fold patterns and get an idea of how it was put together.

I plan to clean up these images and generate a pattern which can be printed out via a large format printer at a FedEx office or similar.

The pieces I have are too fragile to use and would crumble if handled more than a few times.

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

Download the PNG file HERE (56MB)

I have several of the loud speaker instruction sheets and they seem to be generic enough to suit any of the horn type loud speakers. As far as I know they all have a similar adjustment underneath and all users should heed the warning about connecting them to the receiver with the correct polarity.

As with all the images I have used full color images so you can see the original colors and then change it to black and while to increase contrast for printing.

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

Download the PNG file HERE (54MB)

This is the Atwater Kent Radio Service Manual from 1928.

This manual covers from the Model 10 to the Model 52 including accessories such as the power units and loud speakers.

This manual was a pain to find so hopefully this will help some people out and ease frustration.

Download the PDF file HERE (8MB)





This is the Atwater Kent Radio Instruction Book Vol. 2 from 1925.

The instruction book covers the Model 10 through to the Model 24 and contains important photographs showing battery cables, battery boxes and other accessories.

Download the PDF HERE (14MB)








I'm looking for high resolution scans of the following two forms: F91A and F101 as shown in the picture below. If you have scans or can point me in the right direction I would appreciate it!

PC power supplies for Amateur Radio equipment?

I've noticed a few spirited discussions regarding modifying computer power supplies for use with Amateur Radio equipment. On the surface it seems as though they supply the perfect solution: Inexpensive, high current, regulated 12V DC supplies for a fraction of the cost of specialized amateur equipment. Is it really is as straight forward as lopping off a molex connector and replacing it with an Anderson Powerpole?

By design PC power supplies are designed to output a fairly well regulated 3.3V & 5V to the PC motherboard and 12V to the motherboard, fans and hard-drive motors. Modern units are typically rated anywhere from 75W to 1200W which should be a measurement of the output power available from all the 3.3, 5 and 12 volts. Since this isn't a lab grade power supply you can expect marketing hyperbole has perhaps inflated the power output figures.

Back when my job was to build PCs I had an issue with a server not being able to start its complete complement of disk drives. When I opened the case I found a 300W desktop supply board had been used in place of the 800W board ... sometimes you don't even get what you pay for!

Before you convert your first PC power supply there are two issues that may, or may not, cause a problem depending on your unit.

The first is load regulation or the ability of the power supply to maintain its rated voltage under load. If the output voltage drops too far your rig will shutdown, distort or fail to provide its rated output power.

The second issue is due to the high frequency switching circuits used in switch mode supplies. Depending on the individual power supply there can be adequate to no filtering to prevent radio frequency interference being broadcast to your receiver. Toroids on the input and output lines can help to reduce interference.

Because of construction differences between models and even between batch numbers for the same model you can never be certain how the power supply you purchase, or recycle, will perform. For the most part people's experiences have been positive but I have heard of power supplies that were unusable because of RF interference or such poor load regulation that the 12V rail dropped to 11V under load.

Without a motherboard presenting a load and supplying the power-on signal there are a few changes that need to be made to the power supply. Modern power supplies will not enable the 12V output unless the power-on wire is grounded and a load should be placed on the 5V line to help with regulation. Additionally there is usually an adjustment that can be used to raise the voltage above 12V

The following links detail the steps required to convert a PC supply for use with amateur radio equipment. Whether this represents a good investment of your time will depend on your desire to do-it-yourself and the quality of the power supply you begin with. I've heard strong opinions either way but I'll just say that, if luck favors you, you'll save some money and learn a few new skills in this exercise.

Computer Power Supply Converted for Ham Use

CONVERTING COMPUTER POWER SUPPLIES (Advanced with theory)

Converting Computer Power Supplies to stabilized 13.8 V DC 20 A

An oscilloscope clock - Recycling vintage equipment without destroying it.

As a fan of vintage electronics, and vintage technology in general,  I love to see things being re-used rather than being dumped in the trash. This has the very desirable effect of preventing sometimes toxic chemicals from being released into the environment and reduces the demand for new parts that can also involve toxic chemicals during their manufacture.

The only downside to this recycling is that frequently the original function of the equipment is lost so I was pleased to see this creation from Bob Alexander. He has combined one of the oldest types of test equipment with some of the newest microprocessor based devices to bring us a Oscilloscope Clock that still functions as an oscillloscope!

Heathkit oscilloscope with AVR Oscilloscope Clock module

Bob ran into some problems while installing the AVR Oscilloscope Clock Module but was able to invert the horizontal output from the clock module before feeding it into the scope. To read about his build in detail have a look at : An Oscilloscope From the Trash

A small modification to the rear panel to allow setting the clock and switching between clock and scope.

Check the video below for a demonstration of the Sparkfun AVR Oscilloscope Clock Module in action on a significantly newer oscilloscope.

More cheap power supplies ...

Looks as though more folks have been putting "bargain" power supplies to the test and finding them wanting. This time it is a 5 volt USB power supply purchased in the UK that fails to deliver its advertised load.

At 560mA load the voltage has already fallen below 3 Volts, a far cry from its rated 1 Amp!

As most power supplied are simply featureless black boxes it would be nice to be able to rely on the specifications stated on the outside ... sadly you can't as the video below shows.