Marconi S.W.B.8W HF Radio Transmitter
final amplification stage

The Marconi S.W.B.8 HF transmitter was originally produced in the late 1930s as a shipboard transmitter, having an all-brass carcass construction for corrosion prevention. These units were used by the Australian Army in World War II, and after the war about a dozen units were purchased by DCA.

Given the DCA stores identification Y5-6081, these units were commonly referred to as 'Swab 8s'. They were used on point-to-point radioteletype circuits linking Sydney, Darwin, Perth, Cocos Is., and to overseas stations.

Very reliable and robust, they were a good example of the best quality professional transmitter available at the time. They remained in Departmental service from the mid-1950s until the mid-1980s.




ManufacturerMarconi, England
Type of serviceHigh speed (machine) Morse (CW), and later frequency-shift radioteletype driven by a high stability frequency shift exciter (KY5 keyer) specially developed by DCA to overcome frequency drift problems of earlier equipment.
Frequency range 3 to 22.2 Mc/s (MHz)
Output power 2 to 3.5 KW
Valve types

Output - ACT9
Earlier stages - 807, KTW61, ML6

Power supply - G020 (mercury vapour)

The Airways Museum's S.W.B.8 was in use in Darwin. When removed from service it was filthy with years of accumulated grime, and a dead snake was found in the bottom of it!

The unit was restored to its present pristine condition by Museum volunteer Ron Sevior (below), in 2000. Perspex panels permit a view of the interior which would have been covered by brass-mesh plates in service.


Ron Sevior

(Photos: CAHS collection)


Airways Museum Virtual Tour




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