This item has been shown 0 times.
***VERY RARE ORIGINAL MARCONI-STYLE SPARK GAP RADIO TRANSMITTER *** This is a very rare, early spark-gap radio transmitter,dating from the early 1900's. Unusually it is in TOTALLY ORIGINAL and WORKING CONDITION and is a superb piece of scientific and radio history. Based on a laboratory type induction coil it represents the earliest form of radio communication- full information on its use and history can be found on various web sites and, in particular, on YOUTUBE. The earliest radio experimenters coupled the extremely high voltage output to a large tuned L-C circuit and thence to a high, wire aerial. Messages were sent by triggering the coil primary with a Morse Key and reception achieved at short distances by means of a coherer (an early form of detector)-later technological advances increased the reception sensitivity by using different detector systems and tuning formats and it was with a very similar transmitter (albeit at much higher power!) that the very first transatlantic two-way communication was established between sites in Cornwall, England and Newfoundland, USA. Using this particular transmitter it has been quite possible to replicate these early ground-breaking tests and information on how to achieve this is available from a variety of web-based sources-this unit has been demonstrated to various students, with home-made detectors, and the results have been quite awe-inspiring to attendees at these demonstrations! Because of the nature of spark-originated transmissions considerable interference may be caused to legitimate broadcast and communication services and its use should only be condoned for short OF THE TRANSMITTER
The unit is in superb, museum-quality condition. The solid mahogany base has the terminals and various adjustment knobs in excellent,un-corroded condition. The insulation around the main coil body and end cheeks is absolutely pristine, with no cracks or scratches and the plating on the primary change-over switch and primary trembler assembly is in excellent condition. The spring trembler contacts have only light wear and the primary trembler gap length and spring pressure is fully adjustable using the knurled adjustment knobs shown. The coil insulation is first-grade and no tracking or breakdown has been experienced. Dimensions are 56cm x 45cm x 28cm with a weight of approximately 20Kg. A 12volt, 17aH sealed lead acid battery and connecting leads to power thetransmitter is included in the listing -this can be charged from any car battery charger or This is a rare and authentic item of early radio history and is ideal for a museum or serious collector.
On 21-Jul-13 at 19:26:46 BST, seller added the following information:
The dimensions and weight given above are incorrect-the corrected dimensions are 53cm x 28cm x 27cm and the nett weight is 10Kg
On 21-Jul-13 at 19:33:56 BST, seller added the following information:
Shipping to most European countries will cost £40GBP by tracked carrier, Fedex or similar, with a 3-4 day delivery time
On 23-Jul-13 at 12:31:12 BST, seller added the following information:
OPERATING The input to the transmitter primary coil is 12vdc at an approximate current of 3-5 amperes-resistance is 4 ohms. Using a standard sealed lead-acid battery of 17aH charged capacity a spark length of over 80mm was achieved, representing a voltage of 80,000-100,000 volts at normal atmospheric pressure and with pointed electrodes.