Hi,
I have an HP 11729B that looks an anwful lot more like an 11729C, complete with the 640 MHz input (BNC) and output (SMA) ... as you may know you can apparently link these two together to use an "interanal 640 MHz" to drive the comb filter generator.
It's not actually an oscillator output to feed the amp input, but the aux output of the 640 MHz power amp, at about +12 dBm .. fed through a suitable attenuator back to the input it self-oscillates (or is supposed to) at around the peak of the input tuned filter.?? I've tried with a 10dB pad and a 5dB pad ... both of which should be enough to cause it to oscillate,? its would get around 2.5 dBm at the input, which is sufficent drive, assuming the phsae shift is there or therabouts. any other clues as to what the approx value of the HP magic cable attenuator is?? The part number is? HP 11729-60096 or 11729-60098? but I can find no further info on it.? Maybe it is just a series capacitor or something?
