[Milsurplus] BC-960, all the 6SH7s

[Help - trapped in surplus store]

Yo Jack on the above

The British invented a flip-flop using a pentode called the Phantastron
(leaned on word 'fantastic')  Operation related to screen-pentode something.

Mk III IFF was British so res ipso loquitor

I'm gessing the incoming pulse stream from the interrogator was stored
in that batch 'o tubes & the return pulse width's were the "code of the day."

That help confirm/deny any BC-960 maintenance manual stuff you're reading?

Big wonderment remains -  why three 2.5 sec "I-band sweeps" to doit?

As an aside, imagine the Iapx assembly code to fabricate this today.  And if
it was today the programmers wouldn't understand a whit about the system
which wouldn't keep them from churning out code.