TEK TR 502

Chris van Lint

The tracking generator I use with my 7L14 has given up the ghost. When looking at circuit page <4> "Operational Logic, Voltage Regulator and Phase Lock Circuitry" I find that the voltage at the junction of R444 and the collector of Q445 is not 0.01 as shown, but in fact varies between 14.5 - 15.0 V at a rate of about 2 Hz. I suspect that this may be because the phase lock circuitry cannot find a suitable input signal. This in turn I suspect may be due to the 2.095 GHz oscillator shown in circuit page <2> A 140 "2.095 GHz oscillator and amplitude control assembly" not functioning. Could someone please have a look at the circuit and confirm, that my understanding of this circuit is correct i.e. that even without any signal being fed into the LO1 and LO2 inputs of the Tracking Generator, (in other words no conection to the Spectrum Analyzer), I should expect a fixed 2.095 GHz signal at the SMA male connector, which connects to the RF female socket on the A110 "Output Mixer" device.



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