Sunday, January 24, 2010

Rock-Mite 80, first test

Here, the first oscillator test. Well, when writing oscillator, I actually intend to say that I only look at the oscillator's output, although there is only one part missing, preventing the power amplifier to amplify, namely R18 (as mentioned before).

The buffer seems to be working fine, when keying dots or dashes, the amp-meter of my power supply moves, good sign, I think. For seeing where the Rock-Mite is frequency wise, the HF3 + E-probe took the following spectrum.

What you see here, someone switched off their telly ;-) The carrier at 3579600 is the RM80's oscillator when the transceiver is not keyed. I keyed the transmitter twice with dashes and once with dots. You may realize that the line created by the dots is slightly wider, as one would assume.

The spectrum shows what the initial pull of the crystal is. Playing with PWM, we can be anywhere in between the two frequencies. I will perform another test with the Ramsey QRP80C in order to find out where this transmits w/o further tweaking.
I believe it would be most sensible to select our color burst QRPP-range according to what most kits will do OOB (well, when built that is).

And, btw, the Rock-Mite 80 was originally designed with a color burst crystal, as the supplied schematics suggest.