The Model 410A is a peabreading type voltmeter and is
SO designed that it measures the positfve peak value of the
applied voltage. This propesty allows tho 1'loCit.f 413A to be
. used to measure the positive voltage rise in a pulse, pro-
vided the reading obtainec! is multiplied by tlie factor
where tl is the duration of the posi.tu3.vc portion of
tho voltage,
t2 3.s the duratd-on of? the negative portioii of
the voltage,
K is a factor which i$ a Punct-ion of the source
impedance of the pulse gemrator anti of ti,
PRF is th3 pul.se repetition frequency in pulses
per second.
In general if the pulse repetition frequency 1s greater
than approximately 400 or 509 pps, the above factor reduces to
K can be found by use of the cuwcs on tho next page
when the Impedance of the pulse generator Ro in k11,ahms and
tha duration of the positive portion of the pulse ti in micro-
seconds are kn07m. For exanylo, in *the case of a posthive
pulse of 1 microsecond and a PRF of ICQO, and assumin? R= 2
kilohms, Ro/tI -2, K = LY.1 and ths m~lt'iplying factor ~mld
thcn be 1.4 (1 + 11999 + 15.l/lOQ)
For the case of a 1 microsecond negahfve pulse ma a
PRF of' 1000, tl would equai 99 microseconds and t2 t~ould
equal 2 microsecond, Thus Ro/Z~ woulld he npproxims'tely 0
and therefore (from cmvesj K would also be approximately 0,
The multiplying faktor would then be 1/4. (3, 4- '%9/1). Bellcc,
it, may bo seen that in the case of negative pulses of short
duration, much smalley meter readings will be obtained. than
for an equivalent positive pulse, and unless the pulse voltage
3.s large, these measurements may be Lmpracttcal. |