the SSR-1 manual
http://gmcotton.com/ham_radio/misc%2...ver_Manual.pdf has the bipolar version. While the alignment instructions available on BAMA has the mosfet version, as does the Standard C6500 manual available on mods.dk.
The alignment instructions invite one to "rock" VR1 (which adjusts the free-running frequency of the astable) to determine the points at which the lock frequency changes above and below 1 MHz and set it half way between the two. There is a hand written note to the effect that VR1 is not present on all sets indicating the change to a divider type circuit.
The reason for the change becomes clear on reading this
http://www.qsl.net/pa2ohh/06ssr1.htm seems like temperature effects could easily shift the free-running speed of the astable sufficiently for it to lock on to the wrong increment of the 10 MHz crystal osc. Presumably the kludge board was an interim measure until the main board could be redesigned, but why didn't they just use a 1 MHz crystal osc?
Interesting stuff I think, or perhaps I'm just easily pleased!
NHH