Marconi Gannet Transmitter and Receiver

[Julesomega]

The Marconi Gannet equipment was a series of units for use in small ships to provide telephone and telegraph communications and direction-finding, in the frequency ranges 190-530kHz, 625-1600kHz and 1.6-3.8MHz ("TB"). The units are Receiver Type 1159A, Transmitter Type 1158A, and four Loop Aerials Types 1160A, B, C or D.

These were manufactured in the mid-50s. My receiver handbook has been annotated with the date July 1956, and the only component markings I can find that seem to show a date are 1957. The valves are B7G types W77, 6F33, Z77 and D77, an internal Power Supply requires 24V DC and uses a vibrator to output 240V HT. One tuned RF stage and three 600kHz IF stages, with 5 bandpass-tuned IFTs, one of which is switched for 'wide' and 'narrow' bandwidths of 3 or 7kHz at -6dB. An audio filter is added for CW giving 250Hz b/w at 1kHz. Audio output is to a loudspeaker and a headphone socket.

Two loop sizes were offered, 17" square or 24×28", either with the option of aprinted direction scale. All were to be mounted on the cabin roof with a hand crank. Two further options were an internally mounted Rejector Unit for 6 preset frequencies on the 'Trawler Band' selected by a motorised switch to allow duplex phone operation, and a Metering Unit to monitor valve currents: this is shown as having a 6-position switch fed from 12 sensing resistors in the receiver - I don't know how that worked.

I attach photos of the receiver, and I would be interested to see images of the matching transmitter.

[G3VKM_Roger]

Hi Julian,

Did you look at this site?

https://www.internalfire.com/ifod/qd...lt=false&pos=1

They list the Gannet transmitter.

Regards

Roger

[Julesomega]

Thanks Roger - they do indeed list it, just a pity they don't show it!