"I am often asked how radio works. Well, you see, wire telegraphy is like a very long cat. You yank his tail in New York and he meows in Los Angeles. Do you understand this? Now, radio is exactly the same, except that there is no cat." : Albert Einstein
Showing posts with label signal generator. Show all posts
Showing posts with label signal generator. Show all posts
One of the things that always fascinated me about radio was the ability to take discrete components and craft something that could pluck invisible radio signals out of the air. Once I learned more about electronics, some of the magic was replaced by admiration for the many generations of engineers and experimenters that had developed the radio art. Until recently, the theory behind crystals had not solidified (crystallized?) in my mind and so they remained one of those "mysterious devices".
The following film, like most produced during WWII, is a thorough explanation of the history and technology behind radio crystals. It was produced at a period when crystals were instrumental in securing reliable communications between military units, saving lives and coordinating the moment of supplies, troops and equipment.
A very neat construction project from Miroslav Cika. Miroslav's project generates square waves up to 2.22 MHz and pulses with a variable duty cycle from 1-49% and 51-99%. Output is either 5 Volt TTL levels or an adjustable 0-3.38 level.
This piece of test equipment could be very useful for designing and debugging digital electronics. The design is flexible enough that it can be modified to suit your needs. Click the following link to go to his page describing the build process : http://www.arthropodsystems.com/SquareWaveGenerator/SquareWaveGenerator.html
Should have been an easy fix but I suspect, after running a few searches through Google, that it is suffering from the dreaded silver mica disease. This would require taking the IF coil cans apart and replacing the integral silver mica capacitors with external units, not a project for the feint of heart!
Another day perhaps ... there are other projects to complete first.
Zenith 6J05 chassis and IF cans, looks simple enough doesn't it?
Front view of the Zenith chassis, the dial light also requires replacement.
Tubes! ... Some will be used in a homebrew transmitter.
The EICO signal tracer (behind the box of tubes) is working fine now but the EICO RF signal generator requires work.
An old tube AF power amp, low pass filter, coils, chokes and my meter collection ... there is even an RF ammeter in there somewhere.
