This is the 2nd article from Derek Gardner on British AFV Intercoms and
deals with the crew headgear and controls.
Head sets & Helmets
Once you have installed an intercom which headset do you use?
Well there are a few options that you can chose from depending on
your needs.
Early Pattern "Turnip" crew helmet
This type of helmet was developed for the Swedish army by Racal
Amplivox and was later modified by the adding of a boom microphone
to suit British army requirements. The helmet is a one-piece moulding
made from a fibre glass type of material and is designed to withstand
the impact of a 6mm steel ball at a velocity of 130m/s.
The helmet incorporates built in earphones with acoustic valves, when
in the closed position they stop high ambient noise levels, but when
open allow the wearer to hear voice commands as well as protecting
from sudden high noise levels from gunfire and explosions.
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The helmet comes in one size and is adjusted by adding and removing Velcro pads from within the helmet.
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Latter type crew helmet
This type of helmet comes in two main components the head set which has all of the features of the above helmet, but with greater ear protection and an outer helmet shell made from a composite material, which is attached with two press studs on the earphones. This allow for the wearer to only use the head sets for non combat roles and add the helmet for situations were protection is required.
Side comment from Doug: having used these acoustic valve earphones in a Chieftain tank, I can vouch for the effectiveness of this concept. It is quite handy to be able to slide the valve control lever to the open position on each ear (or only one) so as to talk - off intercom - without having to lift the headset off.
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Standard head sets
A standard headset, designed to be used on man-pack sets could also be used within an intercom system but this offers no ear protection for the wearer, but is of a lighter construction.
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Crew leads
One important addition to any system is the crew leads, without the lead the wearer would have reduced movement within the vehicle, the lead also incorporated a “pressel” switch which operates the boom microphone this will reduce the background noise coming over the intercom system from open mic’s when the vehicle is travelling, and can be locked in the open position for the driver to allow hands free operation.
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Conclusion
Avoid the early type of helmet, they are cheap but unless you have a smaller than average head (my 3 ½ year old son complains when you try to put the helmet on him!) you are onto a loser. They are only good for hanging on the outside of the vehicle for show. Go for the later type head set with maybe one or two helmets, the driver should at least have one for road and cross country work to protect him from sudden jolts!
I run four headsets in my Mk 1 / 2 Ferret, 3 later type headsets, one fitted with a helmet for the driver. One additional standard headset for use outside the vehicle, fitted to a 20ft extension lead (very usefull for talking to marshals at shows as well as reversing into tight spots!) All are fitted with crew extension leads, with the driver's and commander's in the open position.
Derek Gardner
England
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