A couple of days ago, I thought the good people of Mastodon - a calm, peaceful place - might like to see the latest iteration that I've drawn of the Marconi 'Carnarvon' VLF station as it appeared between 1925 and the station's closure in 1939.
The latest version isn't some fundamental new interpretation. It's just a more realistic positioning, rather than a merely indicative one, of the final VLF antenna (initially intended for shortwave use), operating from the 'GLJ' valve transmitter (in pink).
Here's what this now looks like (click on the image for a full-sized view):
Since the first iteration of this schematic, I've learned that the No. 2 antenna was fed not by buried twin feed, but by a caged twin feed that ran along timber telegraph poles. This has, by a very good stroke of luck, been confirmed by a 1925 photograph that had narrowly escaped being put in the bin after its keeper had died.
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| Caged twin feed to No. 2 antenna on poles at left. Poldhu pots were installed at regular intervals along the route and equally regularly needed replacement. The antenna in view is No. 1. |
Photos from the same collection also show distinct arms or standoffs emerging from near the top of the northernmost line of masts for No. 1 antenna. They are absent on the southern line of masts and it has long been the case that no concrete anchors or bases for GLJ/No. 3 have ever been identified. This almost certainly means they were for suspending the GLJ, No. 3 antenna from No. 1's masts.
Images in the Oxford Bodleian collections confirm the alignment and extent of No. 3 antenna, though it was experimentally both shortened and lengthened somewhat early on in its life, owing to considerable interaction problems across the No.1 and No.3 circuits - something that took nearly two years to fully resolve.
So that's all good and, hopefully, useful to the wider world; the IEEE History Center certainly think so, in a plaudit they issued at the end of last year.
Having posted the schematic on Mastodon, I very quickly received a question from VK6VCC, simply asking "was this your source?", providing a link to a Welsh Country magazine article that contained very similar diagrams.
I have to say I immediately didn't like the tone of the post which, in the absence of any further question or comment, could be interpreted as suggestive of some skulduggery on my part. It was pretty likely - confirmed by doing it myself - that VK6VCC had conducted a 'reverse image' search on my schematic and had been presented with the similar image linking back to the magazine.
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| Output (right panels) of a reverse image search based on my latest schematic (left panel) |
I'm not sure about VK6VCC's motivation in conducting a reverse image search and it's possible he didn't mean to imply some odd 'goings on' at my end at all. But he certainly seems to have entirely missed, in asking his question, that the author of the Welsh Country magazine article was, er, me!
Hardly surprising, then, to find a reverse image search match. It even gives my name at the end of the article, and that I'd written a full, 230-odd page history of the 'Carnarvon' station, which is available, now for free (but fully copyrighted, all the same), from here (about 70Mb).
VK6VCC didn't respond in the time I gave him as to his intention in asking his original question. Looking him up (13/01/2025), he says he's a new operator. He may wish to spend more time reading and less time rushing to punch a keyboard. He is now one of very few people over the past year I've blocked on Mastodon. He didn't, after all, ask anything useful, because you don't ask the author of a work whether their source is their own - and same - work!
