Ham4CW
Administrator
The original design for these practice oscillators appeared in an issue of the Maplin magazine. They were then sold in kit form, possibly mail order only.
If this were just a practice oscillator and nothing more then it would not really be of any great interest, but this unit has a trick up its sleeve. Apart from the more usual volume and tone (pitch) controls there is one marked balance. What this control does is allow the mixing of white noise in with the CW practice tone. This might seem a puzzling idea at first, but what it allows the user to do is simulate signals off-air with varying levels of signal to noise.
It is so much more pleasant to listen to a tone that is 'resting' on a bed of smooth noise than the rather jarring effect produced by some units where the tone is the only sound source. It is also possible to construct a simple sound keyer circuit to allow the output from a Morse Tutor to key this unit. Again, when the balance control is adjusted so that the CW tone is well down in the white noise it really does seem that you are listening to a weak station, and this provides further excellent practice.
The unit is powered by internal batteries, or you can use an external supply. There is also a recording output which allows you to make up your own audio recordings for even more practice possiblilities.
I would thoroughly recommend these practice units without any hesitation, and it is a great shame that they are no longer produced, though fortunately they do appear for sale from time to time on online auction websites.
If this were just a practice oscillator and nothing more then it would not really be of any great interest, but this unit has a trick up its sleeve. Apart from the more usual volume and tone (pitch) controls there is one marked balance. What this control does is allow the mixing of white noise in with the CW practice tone. This might seem a puzzling idea at first, but what it allows the user to do is simulate signals off-air with varying levels of signal to noise.
It is so much more pleasant to listen to a tone that is 'resting' on a bed of smooth noise than the rather jarring effect produced by some units where the tone is the only sound source. It is also possible to construct a simple sound keyer circuit to allow the output from a Morse Tutor to key this unit. Again, when the balance control is adjusted so that the CW tone is well down in the white noise it really does seem that you are listening to a weak station, and this provides further excellent practice.
The unit is powered by internal batteries, or you can use an external supply. There is also a recording output which allows you to make up your own audio recordings for even more practice possiblilities.
I would thoroughly recommend these practice units without any hesitation, and it is a great shame that they are no longer produced, though fortunately they do appear for sale from time to time on online auction websites.
