Hickok 600A Manuel - Sayfa 4

Test Ekipmanları Hickok 600A için çevrimiçi göz atın veya pdf Manuel indirin. Hickok 600A 6 sayfaları. Tube testers

6. PLATE VOLTAGE TEST: No adjustment. This voltage is entirely dependent on the power transformer and the AC line

setting. See also ADJUSTMENT CHART 1, LINE ADJUST above. If the AC line test circuit is reading correctly, check

and/or replace the type 83 rectifier tube.

7. SCREEN VOLTAGE TEST: No adjustment. This voltage is entirely dependent on the power transformer and the AC

line setting. See also ADJUSTMENT CHART 1, LINE ADJUST above. If the AC line test circuit is reading correctly,

check and/or replace the type 5Y3 rectifier tube.

8. REDUCED SCREEN AND GRID BIAS VOLTAGE ADJUSTMENTS: Earlier versions of the 600 do not have the

provision to reduce the screen voltage. Pressing P1 will have no effect on the screen voltage. For later versions the 56 volt

reduced (P4 and P1 pushed) screen grid voltage measured in step 8 and the –39 volt control grid bias voltage measured in

step 9 is set by adjustment of the two taps on R6. If adjustments are necessary to either the reduced screen voltage or the

grid bias voltage, adjust the control grid voltage first because that affects the reduced screen grid voltage also. Before doing

any adjustments always verify that the screen supply voltage is 130 volts. Adjust the AC line control until it is.

In both versions of the 600/600A the grid bias is controlled by the series combination of R6 a tapped power resistor,

and R7 the front panel BIAS adjust control. Remove the tester from the case and prop it up on a work surface face down

such that you can reach and push the control panel buttons P4 and P1. Set it up with the top edge of the control panel facing

you and the panel meter to the right.

To set the grid bias voltage, adjust the BIAS control fully clockwise. Loosen the clamp screw of the sliding tap on

resistor R6. This is the tap with the jumper wire to the end tab on R6. Gently hold the tap with insulated pliers and slide the

tap until the voltage is as close to –39 volts as you can get it. Tighten the screw to secure the tap in place. Don't over

tighten the screw. Only enough pressure to keep the tap from sliding is sufficient.

On later versions to set the reduced screen voltage perform test 8. Loosen the clamp screw of the second sliding tap

on resistor R6. This is the tap that is not connected to the end tab of R6. Gently hold the tap with insulated pliers and slide

the tap until the voltage is as close to 56 volts as you can get it. Tighten the screw to secure the tap in place.

There is some interaction between the two adjustments so repeat tests 8 and 9 and adjust as necessary to get both

voltages within the limits.

9. GRID BIAS VOLTAGE: See step 8 above.

10. GRID SIGNAL VOLTAGE TEST: No adjustment is possible for this voltage. The voltage is entirely dependent on the

power transformer and the AC line setting. Make sure that the AC line setting is correct and that the AC line set function is

working properly.

11. PLATE SUPPLY BALANCE TEST: This is entirely dependent on the power transformer and the rectifier tubes. If

balance is incorrect replace the 83 tube.

12. SCREEN SUPPLY BALANCE TEST: This is entirely dependent on the power transformer and the rectifier tubes. If

balance is incorrect replace the 5Y3 tube.

13. METER BRIDGE BALANCE: The meter bridge balance is determined by the relative positions of the upper and lower

halves of the ENGLISH control. The ENGLISH control is designed so that the two halves form the two legs of a balanced

bridge circuit. As the control is turned clockwise the two halves decrease in resistance by the same amount thereby

decreasing the sensitivity of the bridge so that higher transconductance readings are displayed without over scaling the

meter. The resistance of both halves of the control must track each other as they are rotated or the bridge will become

unbalanced, adding or subtracting a constant number from the correct reading. If the power supply is properly balanced and

the meter does not read zero or close to it with this test, the ENGLISH control is not balanced. If the control becomes dirty

and intermittent the resistance will change abruptly and deviate from normal as it is rotated causing the zero to fluctuate or

jump adding error. Because these are not high precision controls some fluctuation is always going to be seen as they are

moved through the full span of rotation, especially at the end points and sometimes when the direction of rotation is

changed. If the total fluctuation is on the order of four or more small divisions on the meter and cleaning doesn't help, the

only solution is to replace the control. To clean a dirty control, follow the Control Cleaning instructions given below.