Wednesday, 7 June 2017

Digital radio, LED lights and an external antenna

The general lighting in my shop is very good. However I did notice that there were dark spots particularly at my assembly table and bandsaw. I looked at the new LED lighting strips meant to replace standard fluorescent strips but in the area I wanted to increase lighting levels strips would not be practical.

I then looked at RO80 lamps and they suited the area. I bought 10 E27 bases and fixed 5 of them in place. One per roof joist over the assembly table and one behind the bandsaw and one in front of the bandsaw.
E27 Lamp Holder

They were wired so that I could have a separate bathroom type pull switch for the two locations.
Bathroom Pull Switch

The LED lamps arrived and I screwed them in. These are cool white 5000K, 700 Lumens, 9W, 240 volt lamps. They have an E27 screw thread and have an equivalent lighting output of a 75W halogen lamp.

I switched them on an the difference was very noticeable. I could now see what I was assembling!
The augmentation of lighting around the bandsaw was also very good.

Lighting above the assembly table

Lighting fore and aft of the bandsaw

5 additional LED lamps in situ.

Then came the bad news. The shop music system has a digital DAB/DAB+ radio receiver. This is the standard in the UK and some other parts of the world. It also has a conventional FM mode. The antenna for this was inside the shop. This is not an ideal situation as the roof is metal and cuts down the signal profoundly. When the new lights were switched off the reception on DAB and FM was just about acceptable. There were some stations that "burbled" as per DAB reception but that was ok to put up with.

When the LED lights were switched on the DAB reception was completely blocked. I put this down to the electronics in the lamps generating EMC (probably inducing it into the electricity supply wiring) and overloading the front end of the radio receiver. I switched over to FM and there was also noise on there and some stations could not be listened to especially in stereo.

I had a quick look on Amazon and found a supplier of external DAB compatible antennas. These were fairly cheap so I bought one.

When it arrived the antenna was assembled and clamped to a 10 foot long aluminium pole. DAB in the UK is vertically polarised so I positioned the folded dipole in a vertical orientation.
The outside of the shop already had a suitable antenna bracket fitted to the external wall so I simply mounted the pole into this. The 75 ohm cable was routed through the inside of the tube.

DAB Antenna vertically polarised mounted on the outside of the shop

Then a hole was drilled through the brick wall into the shop and the cable passed through. The hole was sealed with some external mastic sealant. Inside the shop the cable was routed up and along the walls, clipped into place and passed through into the shop music system. The cable was cut to length and the connector fitted. This was then connected to the radio receiver.

The receiver was powered up and the reception was clear and noise free. The LED lights were then powered up and there was absolutely zero interference and no noise. The new antenna worked fine and the LED lights work great.