Note
QST, Oct 1973, inside front cover.
Beginning in Oct 1975, Henry Radio would add a digital display to a stock TS-520. Purchased together, the cost was $729.00. To have a TS-520 retrofitted with the display cost $129.00.
TS-520S
QST, Jul 1977, pp. 144–145.
QST, Aug 1977, p. 163. (full specs)
TS-520SE
QST, Aug 1979, back cover.
QST, Sep 1979, p. 6. (full specs)
