Education Resources on radar, RF design, antique radios, clocks, and vacuum tube audio

I've added a new page listing useful education resources for making and understanding radar systems, radios, restoring radios, tube audio equipment, and repairing clocks.

These include online video lecture series, sources for data, lists of useful books, and sources of sample data.

Click here for more info:

Education Resources

how to read 'dog bone' resistors from the 1930's

I'm running into some very old resistors while restoring the '37 Silvertone. Here is how you read these 'dog bone' resistors, apparently the Philco color scheme is the same as Sears Silvertone:

http://www.philcoradio.com/tech/resistor.htm

Also note that in the schematics for this radio the unit M means kilo ohm. Meg means Mega Ohm, and ohmega means simply ohms.

The best YouTube Channel: BandersenTV, antique radio and television restorations

If you like the TV show 'This Old House' and you like to restore antique radios or televisions then you will love this youtube channel: http://www.youtube.com/user/bandersentv

It is the television and radio restoration equivalent of 'This Old House.' I am a huge fan and have watched almost every video (there are a few hundred so far). New videos are posted a few times a week.

If you are interested in learning how to restore antique radios and televisions then you can learn much by watching these videos, in fact i think there is a mini-series in here on the basics of radio restoration.

Thank you Bob for your excellent work, we look forward to your next video post.

Completed: Sears Silvertone 4686

I've completed restoration of the Silvertone Model 4686.

I used restore-a-finish on the wood, feedn' wax to buff it out.

Radio also looks great at night with the illuminated tuning dial.

It sounds great and has a nice booming AM sound. Both shortwave bands work and i've listened to many unusual shortwave broadcasts with it. I have also added an ipod input so i can play my vintage music playlist.

Silvertone 4686 console radio, second IF transformer

I had to make repairs to the second IF transformer.

It was not easy extracting this from its case. The top nut was stuck and i damaged the wires feeding both coils while extracting it.

Shown here are photos of each side of the transformer for reference in case you have to repair one in your Silvertone radio.

update: ARRL Homebrew Challenge 3 radio, pre-driver and driver complete

This is the pre-driver and driver board.

5 watts out with -10 dBm drive from the front-end mixer, perfect for driving a good sized PA.