25-11-2015, 01:40 PM
Here are some pictures of what I think is a very early receiver. The box it was in is long gone – I guess the box was useful but the receiver was not considered so. Lucky it never got thrown away! My mate thinks it’s WW1 - so well pre broadcast era then. He also thinks it’s the most interesting thing I’ve taken to him.
The coil is a loose coupler. One end (left hand in the pic) is attached to the aerial and earth and slides in and out of the large centre coil using the large handle above it. The right hand coil is in series with the large centre coil so it is a variable inductor – a variometer and also has a large handle for sliding the coil in and out thereby tuning the receiver to the wavelength you want. The ivorine labels are blank – whatever was on there is long gone – maybe handwritten in to suit the application.
The gubbins on the top centre panel I am not too sure about. There is a detector which uses a carborundum spike – unfortunately the spike is missing. It is similar to the spikes used in early Marconi sets – you can see one here on page 6 –
http://www.bvws.org.uk/publications/bulletins/pdf/BVWS_Bulletin_19_6.pdf
It’s a piece of carborundum fixed atop a metal post. If you look at the pic of the top you can see holes for two spares next to the detector. The detector simply screws a u shaped piece of metal down on top of the spike.
There is a buzzer and a switch that I think switch’s between the phones and the buzzer. Carborundum uses a small voltage (1.5V) to perk it up a bit and when switched to the buzzer it goes off when the detector is set at an optimum point. You then switch the buzzer out and the phones in and adjust the coils to pick up the signal. Once set correctly the two large handles on each end coil are screwed down into place. Next to the detector is something that looks like a small transformer, and underneath the panel there is a small .01 cap and what looks like a choke. I will take a look later. First I am going to clean up the coil terminals as they are corroded and only show continuity when I scratch around with my mm. So that’s a job for my little tub of vinegar!
Does anyone have any idea how to clean the detector? I think its aluminium and vinegar might not be the best thing? It also looks fragile and I don't want to break anything !
The coil is a loose coupler. One end (left hand in the pic) is attached to the aerial and earth and slides in and out of the large centre coil using the large handle above it. The right hand coil is in series with the large centre coil so it is a variable inductor – a variometer and also has a large handle for sliding the coil in and out thereby tuning the receiver to the wavelength you want. The ivorine labels are blank – whatever was on there is long gone – maybe handwritten in to suit the application.
The gubbins on the top centre panel I am not too sure about. There is a detector which uses a carborundum spike – unfortunately the spike is missing. It is similar to the spikes used in early Marconi sets – you can see one here on page 6 –
http://www.bvws.org.uk/publications/bulletins/pdf/BVWS_Bulletin_19_6.pdf
It’s a piece of carborundum fixed atop a metal post. If you look at the pic of the top you can see holes for two spares next to the detector. The detector simply screws a u shaped piece of metal down on top of the spike.
There is a buzzer and a switch that I think switch’s between the phones and the buzzer. Carborundum uses a small voltage (1.5V) to perk it up a bit and when switched to the buzzer it goes off when the detector is set at an optimum point. You then switch the buzzer out and the phones in and adjust the coils to pick up the signal. Once set correctly the two large handles on each end coil are screwed down into place. Next to the detector is something that looks like a small transformer, and underneath the panel there is a small .01 cap and what looks like a choke. I will take a look later. First I am going to clean up the coil terminals as they are corroded and only show continuity when I scratch around with my mm. So that’s a job for my little tub of vinegar!
Does anyone have any idea how to clean the detector? I think its aluminium and vinegar might not be the best thing? It also looks fragile and I don't want to break anything !
. There is a connection for a loading? coil and terminals as well which is why I thought it was a crystal set. However, I can't see a detector!
