This example of a S27 is in a pretty sorry state with corrosion eating away at the upper chassis. If it wasn't for the fact that the cabinet, front panel and below chassis being in good condition, this receiver would probably be deemed too far gone and be committed to my scrap bin. In order to kill off all the rust, everything will have to be removed from the upper chassis, the rust cleaned off and everything treated and a coat of Hammerite paint. Removing the valve bases is going to be time comsuming as they appear to be riveted in place and will have to be carefully drilled out.

These receivers were designed by the Hallicrafter company in 1940 and were in production until replaced by the by S-36 in 1943. At an original cost of $175, they proved to be an invaluable aid to the allied war effort as the following paragraphs will testify.

S-27's were installed in many allied warships where they were used to by the 'Y' service to intercept low-grade radiotelephone traffic in the VHF bands. Manned by German speaking ratings, these activities also gave prior warning to convoys of an impeding air attack and gave the escorts time to lay an effective anti-aircraft barrage.

These Hallicrafters were used to monitor and develop counter-measures against the various radio navigation systems used by the German Luftwaffe to improve their bombing accuracy in poor visibility. One such system was the "Knickebein" which operated around 30Mc/s. This system was eventually discovered in early 1941 using Hallicrafters S-27 receivers installed into Avro Anson aircraft and flown up and down the East coast. The German beams were code named "Headaches" and this led to the receivers being universally known as "Headache" receivers.

On one occasion, S-27 receivers were reputed to have been driven down to Dover by Derek Garrard, an acquaintance of Dr R.V.Jones, where they detected the first emissions (125Mc/s) from the German "Freya" radar system. This system was soon jammed by the allies using purpose built "Navy Type 91" jamming transmitters.

1943 saw S-27/36 receivers installed in warships to intercept and jam the control signals transmitted to German "Fritz X" radio controlled glider bombs. These had a warhead of 320kgs of explosive - enough to penetrate up to 28 inches of armour plate. In their final 10-15 seconds of flight they were steered to their allocated target by the launch aircraft using VHF radio and aided by a bright flare carried in the bombs tail. The Italian Battleship Roma was sunk with this weapon and HMS Warspite severely damaged. Later versions of the glider bomb were wire guided and thus immune to jamming.

The American 36th BOMB SQUADRON RCM (radio counter measures) installed S-27 and S-36 receivers in Liberator and B-17 aircraft where they flew on electronic intelligence (ELINT) flights over enemy territory. These were known as "FERRET" missions. One such mission was conducted during the Battle of the Bulge where AN/ART3 barrage jammers (JACKAL) were used to jam German tank communications. S-27 equipted aircraft were then used to monitor the effectivness of the jamming and the enemies reaction to it.

These radios were eventually replaced by the American SCR-587 and the British R-308 and R-216 receivers.

Heres a couple of pictures of the progress made to the receiver to date. Although the light grey front panel looked original, it never left the factory that colour. A previous owner had resprayed it and made a wonderful job of re-applying the lettering. The crackle finish on this particular receiver was not a product of a special paint but was in fact stamped/etched into the steel in the same way the that the lettering was. This meant that after carefully stripping and primimg, the crackle texture was still present after applying the black semi-gloss top coat. Incidentally, the reverse side of this panel is also textured and stamped with control markings as is if the 1940's machine operator had inadvertantly placed the panel in the press upside down.

Circuit - 15 valve, single conversion, 2xRF and 3xIF stages (5.25Mc/s)

Frequency range -

27-46Mc/s

45-84Mc/s

81-145Mc/s

Sensitivity -

Weight - 75lb

Phones -

Supply - 110V, 50-60c/s AC

Dimensions - 19"w x 9"h x 14"d