RAF Radar Home

Radar Type Numbers

Chain Home Radar System

Chain Home Low

Type 2

Type 11

VT98 valve

Chain Home Extra Low

Ground Controlled Intercept

Post War Planning

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The Chain Home Low radar system

The following advertisement was seen on eBay in July 2001:

British Defense Bottle-CHL RADAR rare!

Reserve price $3,500 - Buy it for $15,000

Seller: rwstephens@hurontario.net

VT98 valve for CHL radar (Photo: R. W. Stephens)No significant collection of historically important valves or vacuum tubes can be complete without this large REL5/VT98 UHF pulse transmitting triode which formed the heart of Britain's Chain Home Low coastal air defense radar network. An Internet search of on-line valve collections, as well as checks with the Royal Museum in London and the Smithsonian in the USA found NO COPIES of this apparently quite rare radar artifact. THEREFORE THE VALVE BEING AUCTIONED HERE IS THE ONLY SURVIVOR WE ARE AWARE OF! This may be your only opportunity to obtain this important artifact which played such an important role in helping win the Battle of Britain!

This valve appears to be New Old Stock, still in its original metal carrying case complete with spring loaded shock protecting carrier inside. The original cloth bag containing drying desiccant still hangs where it was tied inside some 60 years ago. There are no contact impressions visible on the grid spade connector, nor are there any obvious scratch lines showing socket insertion on the filament pins. The glass is clear and the filament shows continuity. There are no particles floating inside or rattles when shaken. The valve measures 13 inches long overall. The forced air cooled anode is 3-1/2 inches outside diameter. The chatty label emblazoned on the side reveals that this valve was the design of/or manufactured by the well documented Research Enterprises Ltd., of Leaside, Ontario, Canada which helped fill the urgent demand for specialty radar components for the allied war effort. The Air Ministry (A-crown-M) Crest is there in its full glory.

VT98 valve for CHL radar (Photo: R. W. Stephens)There is absolutely no question as to the authenticity of this artifact. Noted vacuum tube historian Ludwell Sibley lists this valve on page 131 of his excellent reference book "Tube Lore", ISBN 0-9654683-0-5. "[AKA (Br.) 10E/224,VT98];copper-glass UHF xmtg triode dev. from RAF VT58, used in Chain Home Low air-defense radar and MB2 mobile set. Copper anode, side connection to grid; T-T fil. 12.6 V @ 58 A. Two tubes gave 30 kW peak at 600 MHz max. Major production in 1941. Two were used in xmtr of SCR-588 CHL/Ground Controlled Intercept set." Another source specifies this valve as 100 kW pulse at 200 MHz used singly.

Please note than an insincere winning bidder will be rewarded with negative feedback. Payment by cash of International Postal Money Order in US Funds to be received within 14 days of auction close. Buyer is responsible for shipping and insurance costs. Pickup may be arranged. Due to the rarity of this item I have placed a fair reserve. Additional close-up detail photos may be requested by email for the most serious inquiries only please. Thank you for viewing my auction and good luck bidding.

Keywords: transmitting tube, power tube, Chain Home radar, WW-II.

If you are a philanthropist who does not personally require this item but would like to purchase it to donate to one of the aforementioned museums, or another museum of your choice, you could get a nice tax receipt for your generosity and the satisfaction that one gets from preserving an important piece of history.

VT98 valve for CHL radar (Photo: R. W. Stephens) VT98 valve for CHL radar (Photo: R. W. Stephens)


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Updated 08/07/01

Constructed by Dick Barrett
ęCopyright 2000 - 2005 Dick Barrett
The right of Dick Barrett to be identified as author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.