[ARC5] BC-229 / BC-429 receivers

[AKLDGUY .]

In the BC-229 and BC-429 receivers, a winding on the first RF amplifier
grid coil is shown unconnected in the manual, but at the following site a
diagram shows a switching arrangement that connects it to a socket with 3
pins, 63, 55, 64:

http://www.rkk-museum.ru/vitr_all/exhibits/s509_e.shtml

What is the function of the switching? It looks like the antenna terminal A
gets grounded.

73 de Neil ZL1ANM