SVK Test Model 2

Unit Construction. This model differed from the first as follows:

1. The mirror and B cell were removed and replaced by a photo-cell in ring form in-stalled around the A cell.

2. The cells were made more responsive to the blue-green end of the spectrum. (The manner in which this achieved is a trade secret of the Infram Firm.)

3. The cells were selected from the total number available with a view to pairing those with the most similar sensitivities.

4. The neon-tube relay was replaced with an I relay, form C or form Fu.

5. Exposure of the ring photo-cell to the direct rays of the sun was prevented by means of a sun shade suspended on a rotatable ring made of hardened steel wire and magnetizied to maintain constant orientaiton.

Test Results. Tests were conducted in the Ottersee with satisfactory results. (The Ottersee is apporiximately three miles wide and 12-1/2 miles long, and ranges up to 590 feet in depth.) The target vessel was 65 feet in length, with a 13-foot beam extended to 40 feet by means of wooden floats secured alongside. Firing was obtained at a daylight inteneity of 3,000 lux (beginning evening twilight) in depths of 210 to 325 feet. Test with the same unit at Hela on the Baltic resulted in self-firing during high seas on a sunny day.

Figure 260 – Optical Mine-Firing Mechansims