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The first thirteen slide charts and calculators on this page were generously donated to me by David Shore, who also provided links to Wikipedia pages to help me understand them as my electronics knowledge is rather limited. I apologise now for any errors I may have made in the descriptions.

Ampex International AI.947 Frequency Wavelength Calculator made by Perrygraf, dated 1963. Setiing the tape speed in the upper window enables the wavelength to be read against frequency and the playing time against tape length. There is a small handwritten table under the brand name. The reverse gives details of Ampex instrumentation tapes and the standard configurations for them.

M/A.COM Microwave Power Devices VSWR Calculator ©1989 made by the American Slide Chart Corporation. The Voltage Standing Wave Ratio (VSWR) in radio and telecommunications engineering is a measure of the impedance matching of loads to the characteristic impedance of a transmission line or waveguide (ref. Wikipedia)). It is particularly relevant to the matching of radio transmitters and receivers to their antennae. On the upper side, setting the VSWR to the arrow enables reading the return loss, power reflected percentage and voltage reflection coefficient. On the other side there is a Watts and Volts Converter for a 50 ohm system, and a Voltage Ratio to Power Ratio converter.

Global Microwave VSWR Calculator made by Datalizer Slide Charts. This is essentially the same as the M/A.COM example above.

Hughes Aircraft Compnay Microwave Calculator made by Arth-O-Graf ©1988. On the upper side are, (a) the dBm - Watts conversion essentially the same as the voltage and watts converter on the previous two charts, (b) a VSWR vs return loss vs mismatch loss calculator, and (c) a free space path loss calculator. On the reverse side various noise parameters are calculated for small signal gain, first stage gain, and noise bandwidth.

Nortin Communictions Signal Distribution System Performance Calculator made by Perrygraf ©1978. The large plastic calculator is housed in a paper sleeve (the bottom two pictures). It says “The Nortin Signal Distribution System Performance Calculator provides a convenient means of determining dynamic range performance of wideband multi-stage sustems. The calculator uses five steps to arrive at predicted dymanic range.” The sleeve then describes the calculations performed. The first two stages find the intercept points - the theoretical points at which the intermodulation product levels match the signal level. The remaining stages find system noise, the minimum detectable signal, and dynamic range.

Tecom Industries Inc Antenna Calculations slide chart made by Arth-O-Graf ©1976 Tecom. The first section finds minimum range at a particular frequency for a given antenna diameter. The second section finds force and wind pressure for a given wind velocity and antenna diameter. The next section converts dB to power ratio or voltage ratio; the next noise temperature to noise figure; the last gives sidelobe levels against the ratio of blocking diameter to aperture diameter. On the reverse beamwidth and gain can be found for parabolic antennae. Next the free space attenuation at a given range can be calculated for a given frequency and gain reduction at surface tolerance. Finally return loss can be found for a given VSWR.

Telonic Engineering Co RF Filter Performance Chart made byPerrygraf ©1965. Its construction is slightly unusual as it has two slides (upper & lower). On the upper face section I calculates the Chebishev response. The Chebishev filter has a very steep roll-off at the expense of some rippling in the pass band. Section II relates transmission and reflection to the VSWR. On the underside the calculations relate to tubular band-pass filters giving attenuation at MHz from the centre frequency, percentage bandwidth (3dB) at centre frequency, and insertion loss.

Adams Russell Amplifier Design Calculator made by Perrygraf ©1978. Using the principle of Intercept the 3rd order spurious-free dynamic range is obtained from the first stage gain and noise figure, the second stage gain, and the intermodulation ratio.

EEV Lincoln Microwave Engineering Parameter Indicator. The upper face is Low Power and the lower face High Power. Whilst information given includes various formulae that the calculator is based on there are no instructions on its use. However the high power side is for specific waveguide types and gives dimensions and theoretical CW power rating as well as wavelength and frequency.

Mid-Century Microwavegear Limited Waveguide Data slide chart. The upper side gives power rating, attenuation, and dimensions for a range of standard waveguides. On the reverse the wavelength can be set on the upper axis of the graph and the lower & upper frequency limits and cut-off frequency read in the apertures below.

ECS Low-loss Coaxial Cable Chart and ECS Connector Reference Chart made by the American Slide Chart Corporation no. ASC10713 ©1995. Both sides work the same way - the cable part number is first set by moving the black dot to the window under the part number. On the upper side the electrical characteristics, physical characteristics and system attenuation for the cable can be read in the two main windows. On the lower side the available connector types can be read in the main window.

Sage Laboratories Inc Wireline and Wirepac Selection Key and Parameter Calculator ©1994 made by Datalizer Slide Charts. The upper side gives examples of how to use the chart to select the appropriate coupler using the slide and windows on the lower side.

Hewlett Packard Time Domain Reflectometer Calculator made by Perrygraf dated 1965. Intended for use with the Model 1415A Reflectometer, it could be used to calculate the distance from the round trip time given the propagation velocity or dielectric constant, or to find either of these from the round trip time in a known length of cable. The second side gives the instructions for finding an unknown impedance by reference to a known one using the oscilloscope and the calculator.

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