12-10-2016, 11:27 AM
I made a test panel some time ago that is used in conjunction with my "Poor man's Valve Tester," designed and produced by myself. The other half of it is a box with a one-valve receiver in it, an EF91 is on top. It is tuned in to a station with the EF91 in position. There are flexible leads with plugs on them for Heaters, Cathode, Grid 1, Grid 2, and Anode.
To test a valve, the EF91 is removed, and the valve on test is put in the appropriate socket in the panel shown. The electrode plugs from the main unit are plugged into the appropriate red sockets along the top of the valve-holder panel. Any links required such as G3 to cathode etc, are made with double-spade jump leads to the bottom terminals. There are flexible leads with plugs on them for Heaters, Cathode, Grid 1, Grid 2, and Anode. There are also two sockets on the main unit, with a shorting switch, inserted in the HT line for checking the anode current. The meter is plugged into them and the shorting switch turned to off. HT and LT supplies come from an external source, a variable DC power supply, also designed by myself, that will supply from 0V to about 300 DC. Again, nothing mind-bending, just a variac with isolating transformer feeding into a conventional full-wave silicon rectifier, and smoothing circuit. The LT comes from either 2, 6 or 12 Volt rechargeable lead acid batteries or another variac for higher heater voltages. I am often told it is not up to much for testing valves, but it has served me very well for some time now.
I will be making up a lead and plug to connect my home-made valve-holder panel to the Avo Valve Tester!
Bob
To test a valve, the EF91 is removed, and the valve on test is put in the appropriate socket in the panel shown. The electrode plugs from the main unit are plugged into the appropriate red sockets along the top of the valve-holder panel. Any links required such as G3 to cathode etc, are made with double-spade jump leads to the bottom terminals. There are flexible leads with plugs on them for Heaters, Cathode, Grid 1, Grid 2, and Anode. There are also two sockets on the main unit, with a shorting switch, inserted in the HT line for checking the anode current. The meter is plugged into them and the shorting switch turned to off. HT and LT supplies come from an external source, a variable DC power supply, also designed by myself, that will supply from 0V to about 300 DC. Again, nothing mind-bending, just a variac with isolating transformer feeding into a conventional full-wave silicon rectifier, and smoothing circuit. The LT comes from either 2, 6 or 12 Volt rechargeable lead acid batteries or another variac for higher heater voltages. I am often told it is not up to much for testing valves, but it has served me very well for some time now.
I will be making up a lead and plug to connect my home-made valve-holder panel to the Avo Valve Tester!
Bob
