Galbraith Counter/Timer

By

Branch 05 Projects Group

Cover letter 1
Cover letter
Assembly
Ass 2
ass3
Ass4
Cab Ass5
Cab Ass6
Cab Ass 7
Cab layout
Xral osc
Display bd
input
Main
Oven
point
Pre
programm bd
2
3
psu
test lead

Galbraith counter files addenda

These scanned files were originally typed in 1972 on foolscap paper. I have scanned these & they seem to print OK on A4 but the headings have been left off at times and the bottom few lines are missing in places. These missing lines are shown below. They will need to be read in conjunction with the pages/ files as shown. Rory ZL3HB Crystal oscillator.jpg -- last sentence in bottom right paragragh reads “ Three samples tried by the author gave controlled temperatures of 57.6’ , 59’ , and 62’ . Bottom left diagram is cross sectional diagram of the oven Oven assembly.jpg – In construction of oven item 4, continues “…..soldering of wires to oven and board. When finally mounted, the metal cover will hold the unglued end cover to form an insulated compartment. 5. Drill 1/8” holes in metal flange to match mounting holes in P.C. board and finish as desired. e.g. paint outside white. 6. Using shortest practical leads for crystal, mount oven unit on the copper side of the board. Check for correct wiring of oven & place metal cover, with end pieces, over the oven unit & bolt it to the board using the 4 bolts ( 1/8” ) supplied. Programme board 1.jpg -- Last line after ‘S2 function switch’ = The LED is a Hewlett Packard 5082-4480. The shortest lead is the cathode. Programme board 2.jpg -- After ‘IC 16a provides’… control of the divider output to the gate control, opening on functions 2 & 4. IC24d opens on function 3 only to give gate control from the input amplifier. Input amplifier.jpg -- Last missing paragraph = Note:- A 200pf capacitor should be added across the 1K5 input resistor to improve the sensitivity above 15Mhz. Measured sensitivity is greater than 50mV to 20Mhz & greater than 100mV to 34Mhz. Cabinet ass pg4.jpg -- after ‘to the operate switch under the front of the display board, check that the wires are not restricted and that the display board is fully forward ( if desired file the edge of the 200v rail to prevent earthing ) and screw in position using four ¼” PK’s. Cabinet ass pg5.jpg -- 28. Select FREQUENCY. The GATE OVEN light should indicate cycling of 1 second on & about 20 milli-seconds off. The display will quickly count up…..(over page ) to 1000.000,….