Yes, there is a Crystal inside the generator. Reading the notes in the manual regarding this on the type 63, stets that it is a 5Mc/s crystal and mentions that the cursor is adjustable to the crystal beat, but, the type 63A does not have the adjustment screw which is present on the type 63.
It also states that "the output from the calibrator is available via a socket on the front panel into which may be plugged the probe unit 10670 to connect the output to headphones or to an audio amplifier and speaker.". This answers one of my questions: a special probe is required to reach the contact deep down inside the PHONES socket (as it is labelled on this unit) on this generator. I imagine this is all about shielding.
According to the Crystal Check paragraph under Circuit Description, the output is a "beat note", so this would correspond to your note about listening to the beating between a crystal and the generated frequency as a way to check calibration.
The manual does stated that the purpose is to "provide[s] accurate checkpoints" so does this provide an audible beat frequency with a null or something which would indicate a precise harmonic of 5Mc/s so one could check that dial marker corresponds to a 5Mc/s multiple? Or is 5mc/s the only checkpoint?
I have reconnected the attenuator and the good news is that it seems to be working perfectly fine although reading a signal at x10 and x1 μV is difficult on a scope even with a x1 probe at the 1mV setting, but there is an output. I had a listen with the scanner and you are correct. The Mains reference seems to refer to the FM carrier being modulated with a 50Hz mains signal. On the 75% setting and AM I get a 1kHz tone as indicated.
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Originally Posted by Diabolical Artificer
I replaced the pot with a 10 turn on mine and tweaked the R value's to get an accurate OP in the ranges I was mostly using.
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I am considering the possibility of doing the same. Did you do a straight with a 100ohm 10 turn pot or did you choose a different value?