NEW PRODUCTS
Stable to 0.01% . . . Indefinitely
NEW KEITHLEY
3500V D.C. SUPPLY The extreme stability of the Model 242 is not specified in hours. Now— over several months—you can per form extended duration measurem e n t s . C u m u l a t i v e d r i f t of t h i s regulated supply is prevented by a self-correcting feedback loop fea turing a temperature compensated zener diode reference, photo-chop per c o m p a r a t o r and wire wound sampling resistors. 300 V to 3500 V are delivered at 25 ma, with less than 1 mv combined ripple and n o i s e ideal for photo tube, photo multiplier and electron multiplier applications. Other specifications contributing to the outstanding value of the Keithley 242 are shown below.
N e w Laboratory Recorder
A new laboratory strip chart re corder, Model LS11A, is designed for laboratory and basic research person nel. The door of the recorder "disap pears" into the top of the recorder case where it is out of the way and not mis placed. Front panel mounted gain, damping, zero, recorder power, and chart controls permit easy adjustment. A five-speed dialomatic chart trans mission, plug-in range modules, "tabletop" notation platen, ball point pens, V 2 mv. minimum spans, and zero diode standardization are other standard fea tures. The laboratory recorder is also available as a dual pen recorder, Model LD11A, with both pens writing full scale. Westronics, Inc., 3605 McCart St., Fort Worth 10, Texas. 429
» o u t p u t : 300 t o 3,500 V at 25 m a in 1 v o l t s t e p s — p l u s , m i n u s , or f l o a t i n g t o 4500 V > stability: 0 . 0 1 % i n d e f i n i t e l y , minute warm-up
after
30
• accuracy: ± 0 . 1 % • ripple and noise: Less t h a n 1.0 m i l l i volt r m s ' line r e g u l a t i o n : 0.005% for 10% c h a n g e in l i n e v o l t a g e • load r e g u l a t i o n : 0.005% f r o m z e r o t o full load 1
o v e r l o a d p r o t e c t i o n : A u t o m a t i c dis c o n n e c t if c u r r e n t e x c e e d s 27 m a
• price: $850
Other Regulated DC Supplies M o d e l 241, 0-1000 V, 0.05% a c c u r a c y
$800
M o d e l 240, 0-1000 V, 1.0% a c c u r a c y
$345
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K KEITHLEY INSTRUMENTS
12415 Euclid Avenue · Cleveland 6, Ohio Circle No. 190 on Readers' Service Card
152 A
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ANALYTICAL CHEMISTRY
The carbon dating instrument shown permits high sensitivity measure ments of carbon-14 in the naturally occurring levels. The instrument works on the principle of conversion of any carbon-containing compound into benzene for radioactivity meas urement in a liquid scintillation spec trometer. Sample conversion is to C 0 2 - > Li 2 C 2 - » C 2 H 2 - » C e H e , with an overall chemical efficiency of ap proximately 5 0 % . The final step is done by a catalyst which is activated by the user, or which can be pur chased already activated from the manufacturer. Very low levels of H 3 can also be measured through label ing of the benzene molecules. This is done by hydrating commercial car bide with the water sample to be counted, converting the resulting acetylene to benzene for measure ment. Packard Instrument Co., Inc., Box 4 2 8 , La Grange, III. 430
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Help yourself while you help your country
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