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The RCA 6499 Radechon is barrier-grid charge storage tube, first produced by RCA in 1956, and used in such systems as the SAGE defence computer. The 6499 uses an electron beam to store data on a charged target. Much like modern DRAM, the contents of memory must be continually refreshed in order to be maintained. The 6499 has a maximum storage capacity of 16,000 random-access bits, though its practical capacity is somewhat less, due to splatter on adjacent bits from the electron beam.

Simplified diagram.

The gun assembly within the clear tube. Under the colloidal graphite coating are the two sets of deflecting plates.

The circular barrier grid.

The face-plate with additional connections to backing plate and grid 5.

Another view.

The woven mesh barrier grid g5 showing the holes.

Imaging the wires through the glass was not 100% successful.

The end window envelope is 50 mm in diameter and, excluding the B14A base pins, is 278 mm tall.

References: Data-sheet, The Vintage Technology Association & Lamps & Tubes. Type 6499 was first introduced in 1956. See also 1956 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.