Agilent 1954-08 free download

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HEWLETT' PACKARD JOURNAL TECHNICAL INFORMATION FROM THE -hp- LABORATORIES Vol.5 No. 12 UBLISHED BY THE HEWLETT-PACKARD COMPANY, 275 PAGE MILL ROAD, PALO ALTO, CALIFORNIA AUGUST, 1954 Advanced Performance in Two New VHF Signal Generators IN ORDER for an amplitude-modulated sig have modulation applied to it. As a result, nal generator to be suitable for testing high- modulation voltages do not react on the oscil performance receivers, one of its most important lator and incidental f-m is of a low order. requirements is that it have a low order of The MOPA circuit arrangement has quite incidental f-m. The reason for this is that ap naturally been followed in the design of two preciable f-m in a signal generator usually new signal generators which have been devel causes serious errors in evaluating receiver per oped for the r-f to lower uhf range. The more formance and further leads to misalignment of technically refined of these new generators, the the receiver. Although ordinarily not present Model 608D, operates from 10 to 420 mega in troublesome proportions in lower frequency cycles, is capable of sine-wave or pulse modu generators, incidental f-m tends to be a signifi lation, delivers a maximum of 0.5 volt across cant problem in vhf generators, especially when 50 ohms, and incorporates a 0.01%- tolerance inelegant modulation methods are used. crystal calibrator to permit unusually high accu In the design of -hp- signal generators, free racy of output frequency. dom from incidental f-m has always been an The second generator, the Model 608C, oper important consideration. It has led to the use of ates from 10 to 480 megacycles and provides a master-oscillator-power-amplifier type designs maximum output of 1 volt across 50 ohms. It is for the -hp- generators that operate in the r-f, generally similar to the Model 608D except that vhf and lower uhf regions. The advantage of it does not include a cryst