Sidetone etc. - DX-60

[Steve Harrison]

At 10:49 PM 1999-06-05 -0500, Sandy W5TVW wrote:
>    Sidetone?  That was something that was on some military and
>aircraft stuff
>but not on ham gear!  (Back in those days)

Not as we know "sidetone", as in CW sidetone. In avionics, "sidetone" is
simply a small amount of the microphone audio fed through the pilot's
headphones so that he can hear himself through the noise of the cockpit.
But I think you are right; a VERY few mil transmitters did have audio CW
sidetone oscillators; but if I remember right, those were simply for A2
transmission, for reception on radios that had no BFO.

>I think the circuit originally used the old Raytheon CK-722.  How
>many of you solid state people remember THAT number?  Later I
>think the GE 2N107 was a "sub" for the CK-722.

No, they were not quite substitutable, I don't recall exactly why, I think
the 722 had higher frequency response and was more capable of RF response,
at least through the BC band (!!). The NPN version of the 2N107 was the
2N170. The 107 and 170 were sort of the predecessor of today's silicon
2N2907 and 2N2222 types and all their variants such as the 3904/3906, etc.

73, Steve K0XP

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