Modifying An Analogue Meter.

In this blog post I go all OLD SCHOOL and prepare an analogues s-meter for my  Irwell HF Transceiver project. 

Big thanks to my ham radio buddy Frank G6YAQ who kindly donated the meter for this project.

Call me old fashioned but I much prefer an old analogue S-Meter over the modern digital counterpart so I decided to retain some nostalgia in my Irwell HF Transceiver build and go with the analogue option.

Frank G6YAQ gave me a nice analogue signal meter that he salvaged from an old peice of equipment but it lacked illumination and the meter scale calibration was printed 0 to 5 and not the usual S units of  0 to +60 db.

I partially stripped the meter down to ascertain if it would be possible to change the meter scale and add some illumination, my findings and the process are hereby documented in the hope that the information may help others.

Here is a picture of the meter with the front panel removed.

The meter scale was held in place with a couple of dabs of adhesive and I was able to pry it away without too much trouble.

I scanned the original meter scale on to my PC using a Cannon LiDE220 flat bed scanner and the produced image was used to form a template from which I created the new scale.

The scale was printed onto a sheet of card trimmed to size and then fitted back into the meter housing with the end result shown below.

Next I set about adding some illumination using surface mout ultra bright LED's and a current limiting resistor. The parts were mounted on to small pieces of stripboard and secured in place by the front covers screw pillars as shown below.

I drilled a small hole in the bottom of the front cover and attached the LED power supply cables.

The power supply cables for the LED illumination were attached to a 2 pin Molex connector on stripboard and secured in place with epoxy resin. Here is the finished S-Meter after re-assembly.

Finaly here is the S-Meter shown illuminated, I used some Amber coloured LED's that I had to hand which give off a nice warm glow. It can be seen that there are a couple of hot spots produced by the LED's but I think I can live with that 😉

That's it for the meter modifications, I will be back soon with another blog post detailing the latest progress on the Irwell HF Transceiver project.

 

Until next time...