ferrettkitt Posted October 21, 2009 Share Posted October 21, 2009 a shore station has a known position which won't move relative to the ship which will. An early Direction finder Link to comment Share on other sites More sharing options...
fv1609 Posted October 21, 2009 Author Share Posted October 21, 2009 It's like one of those aerial base coil thingys a YES well done GE I thought you'd given up & gone to bed! It is a loading coil that provides inductance to bring the aerial to resonance. At the time a transmitter's frequency was determined by the length of the aerial itself. On a shore station you could more or less have whatever length of aerial you like. On a ship (HMS Yarmouth) there was a limit to how long or convoluted your aerial was. Hence the need for the coil on the longest wavelength. Still not got a date:whistle: Link to comment Share on other sites More sharing options...
HotBed Posted October 21, 2009 Share Posted October 21, 2009 hi clive, 1907 for your date Link to comment Share on other sites More sharing options...
fv1609 Posted October 21, 2009 Author Share Posted October 21, 2009 hi clive, 1907 for your date Nope, Graham Link to comment Share on other sites More sharing options...
oily Posted October 21, 2009 Share Posted October 21, 2009 I reckon 1905,......:coffee: Link to comment Share on other sites More sharing options...
fv1609 Posted October 21, 2009 Author Share Posted October 21, 2009 I reckon 1905,......:coffee: Nope, a fair way off. Link to comment Share on other sites More sharing options...
ferrettkitt Posted October 21, 2009 Share Posted October 21, 2009 1920 to far away? Link to comment Share on other sites More sharing options...
oily Posted October 21, 2009 Share Posted October 21, 2009 it's ok Richard, was only teasing you,.....where? oh! where? does Clive dig these things up from?...... Link to comment Share on other sites More sharing options...
fv1609 Posted October 21, 2009 Author Share Posted October 21, 2009 Link to comment Share on other sites More sharing options...
Richard Farrant Posted October 21, 2009 Share Posted October 21, 2009 it's ok Richard, was only teasing you,.....where? oh! where? does Clive dig these things up from?...... No worries Oily :-D....this was a bit off my subject area, just stabbing in the dark. Clive has a library of the most obscure military books and you never know what will be next. Link to comment Share on other sites More sharing options...
fv1609 Posted October 21, 2009 Author Share Posted October 21, 2009 1920 to far away? Near enough 1924 Link to comment Share on other sites More sharing options...
gritineye Posted October 21, 2009 Share Posted October 21, 2009 I thought you'd given up & gone to bed! I nearly did but the CB thing gave it away, wood and string technology is more my thing really...... Link to comment Share on other sites More sharing options...
fv1609 Posted October 21, 2009 Author Share Posted October 21, 2009 (edited) Given that transmitters at the time were dependant on the aerial length to determine the wavelength, swaying of the aerial had the effect of varying the height of it & hence its capacity to "ground". This was problem enough on the shore, but on a ship it was difficult. This experimental cruise was to evaluate three experimental concepts under sea-going conditions. One of these was to control the transmitter frequency by a "separately excited grid circuit". The second was to load a long aerial with inductance to allow operation on 4,000 metres. The third was to use a spark gap attachment. Judging by the picture this cumbersome apparatus was taken from a Condenser Transmitter Large Power Shore Station No.14. Although this might seem to be a retrograde step it was to provide a note or at least a noise for operators at receiving stations. The normal transmitter was a continuous wave (CW) that was keyed. In those days there were no BFOs to provide a tone in the receiver nor MCW (Modulated CW) to send a tone out on the transmission. The cruise of HMS Yarmouth from 4th Sept to 26th Sept 1924 was from Portsmouth to Madeira, Las Palmas, Gibraltar & return. The schedule of transmissions on the various wavelengths with the different accessories was monitored & recorded by a number of listening stations. Edited October 21, 2009 by fv1609 Link to comment Share on other sites More sharing options...
gazzaw Posted October 22, 2009 Share Posted October 22, 2009 Basically the TUAAM on the wings of the land rover for VHF does the same thing but electronically adjust (or fools) the radio that it has a longer antenna than is on the mount, unlike the HF where you physically have to add segments to the whip length and tune accordingly Link to comment Share on other sites More sharing options...
fv1609 Posted October 23, 2009 Author Share Posted October 23, 2009 Gary yes, but lets hope the TUAAMs don't get hot like the Yarmouth's loading coil! With that red hot steel box, it just shows what heat can be generated by RF energy at any frequency. Some people seem to think that its just microwaves that can cook. Its just that with a short wavelength it is more convenient to dissipate the energy. That transmitter was far removed from microwaves operating at 4,000 metres (75 KHz). Lets hope nobody was around if they operated it with the door open. Link to comment Share on other sites More sharing options...
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