Heathkit SB-650 Frequency Display

Introduction

The SB-650 is – in Europe at least - not easy to find and often in rather mediocre condition. However the frequency display is a very nice and useful addition to any Heathkit amateur radio station using the SB-10x/HW-10x series radios and provides an important «added value» to the successful operation of an antique station.

Once found, restoration is generally not too difficult even today, no «unobtainium» integrated circuits or centipede SMD parts are used, they can all still be found without too much difficulty. There is even a procedure – described in this text – to make it more useful and reliable.

SB-650 front

That said, there is however one problem: the nixie indicator tubes are another matter. The «nixie-clock» fad has cleared the market of many devices. Replacements are not easily found and usually quite expensive. Luckily they have a very long lifetime and usually they work. When problems arise they are very often caused by the decoders etc.

The work on my unit has been successful and this description will hopefully help others to take out their old SB-650 units, breathe new life into them and use them in their station.

Restoration process at hb9aik: full description

The process and the considerations behind it are described and pictured in the PDF document → SB-650 Frequency Display, Rescue and Restoration. Within the text there is a note refering to a higher resolution picture of the insides of the restored unit which shows all the various items that were part of the work. This is the picture shown below &rarr click on picture to enlarge.

SB-650 open