Mika's very kind offering from Heigl appears to throw new light on this topic.
David J. Childs (Tanks; A Peripheral Weapon?) quotes Kenneth Macksey in The Guinness Book of Tank Facts and Feats:
"Two wireless sets per company were delivered in July 1916, but they were soon returned to Woolwich Arsenal when it was thought that they might interfere with 'existing installations. Tank wireless trials began again in May 1917 . . . In July, six stations were available in tanks for the Ypres operations.' However, these proved to be unsuccessful."
Heigl includes two Wireless Tanks in the line-up at Ypres: "2 Pz.FunkWg. (s. Pz.Kpf. Mk IV [M.G.] mit Funkgerät zur Verwendung außerhalb des Wagens.)"
Tr: "2 Wireless Tanks (Mk IV [with machine guns] with wireless apparatus for use outside the vehicle)" One with 2 Tank Brigade, one with 3 Tank Brigade.
This would seem to be entirely different from the familiar Mk IV with the mast and the wireless fitted in the sponson - a set that was carried in the Tank but had to be unloaded and the aerial set up outside. I think this is a pic of it:
"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.
Next British tank battle he is writing is Cambrai, and there were 9 tanks "mit Funkgerät zum Aufbau von Funkstellen", which are those well known wireless tanks, so these must be different.
So, they tested wireless tanks, rejected them, used two "emergency models" to command brigades in Ypres and made some improvements to those regular wireless tanks so that they were working in Cambrai later in 1917.
Personally I wouldn't trust Macksey. I have a copy of the Guiness Book of Tank Facts and Feats. I think I got it when I was 14 or so and I thought it was rubbish even then. From Heigl's writing, it seems he's saying that Mark IV wireless tanks were Females. I'm not sure how you'd fit a WW1 era wireless in a Mk IV Female sponson.
Yes, sorry, Gwyn. I think we're at cross-purposes. It seems they chose Mk IV females for the portable sets (although I can't see any particular grounds for that), but Mk I (or was it II?) females for the fixed ones.
I share your mistrust of big books, but I find they can often give you a lead into some more in-depth stuff.
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"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.
When expanding the photo (and I may have it wrong) it show it appears that what looks like an aerial on the tank is in fact a pole or something so such that is sticking out of the ground in front of the soldiers.
That's the point I was making, Jim. On the purpose-built Wireless Tanks the mast was fitted to the Tank and the wireless built into the sponson. On the Mk IV Heigl describes, the apparatus had to be set up outside the Tank. If you enlarge the photo you can see that the pole is in 6 or 7 sections. After a bit more reading, it seems this is called the 'fishing-rod' type of aerial. This is the modern version.
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"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.
The "antenna" is outside the tank, that is sure (first picture) but couldn't it be possible that this antenna can be fixed ON or OUTSIDE the tank depending tactical situation? Look to the "modern" CVR-T (British), it was possible to put a large antenna (behind) on the vehicle or a few meters away from the vehicle (with a connecting cable) ??