L
Lucien Nunes
It's only what the chap behind the counter at the telly shop would have been doing 60 years ago. I typed '40 years' and had to correct it. These new-fangled transistors aren't so new any more.
- Jun 10, 2012
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- If you're a qualified, trainee, or retired electrician - Which country is it that your work will be / is / was aimed at?
- United Kingdom
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- Other
- If other, please explain
- Lapsed trainee ( was doing stage lighting 30yrs ago),
+ father of Trainee -who has recently jacked it in !
My electronics are running hot ,
(they need to be for Thermionic emission - Insert Diode here)
Them were the days 90V batteries !
(they need to be for Thermionic emission - Insert Diode here)
Them were the days 90V batteries !
Over the last few weeks I've been using my new JCB toy to lay new drains for a couple of my properties.
Dug up hundreds of cells from these batteries in one particular place.
L
Lucien Nunes
L
Lucien Nunes
Wiring checked and ready to use. I'm going to test an EF37A because that KT66 is known to be duff.
Pinout is similar (it's fairly standard for octal-based pentodes and tetrodes) except the g1 is on the top cap and pin 5 is g3 which is brought out separately from the cathode. 026 510 310 connects g3 and the cathode (pin 8) externally. Vh=6.3, Va=250, Vg2=100, Vg1=-2V. Looking for 3mA and 1.8mA/V.
Pinout is similar (it's fairly standard for octal-based pentodes and tetrodes) except the g1 is on the top cap and pin 5 is g3 which is brought out separately from the cathode. 026 510 310 connects g3 and the cathode (pin 8) externally. Vh=6.3, Va=250, Vg2=100, Vg1=-2V. Looking for 3mA and 1.8mA/V.
Attachments
L
Lucien Nunes
Off we go...
Test insulation by selecting each electrode in turn
This is much better now the switch has been cleaned. Not getting any spurious low (<50MΩ) readings now. Hot tests next:
Just for checks I've popped a 10MΩ resistor between cathode and heater sockets and the tester does indeed show 10MΩ:
Now onto emission test. Dial down the meter range to give a good indication. 2.5mA or so, actually just off the scale on the 2.5mA range:
Test insulation by selecting each electrode in turn
This is much better now the switch has been cleaned. Not getting any spurious low (<50MΩ) readings now. Hot tests next:
Just for checks I've popped a 10MΩ resistor between cathode and heater sockets and the tester does indeed show 10MΩ:
Now onto emission test. Dial down the meter range to give a good indication. 2.5mA or so, actually just off the scale on the 2.5mA range:
L
Lucien Nunes
So the valve is good for emission. Now back-off that standing current to zero:
And switch to mutual conductance test:
Adjust the gm dial until the meter needle is on the index mark:
And read off the mutual conductance which s 2mA/V.:
And switch to mutual conductance test:
Adjust the gm dial until the meter needle is on the index mark:
And read off the mutual conductance which s 2mA/V.:
L
Lucien Nunes
So there it is, one happy tester and one good EF37A.
- Mar 29, 2019
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- If you're a qualified, trainee, or retired electrician - Which country is it that your work will be / is / was aimed at?
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- Practising Electrician (Qualified - Domestic or Commercial etc)
- Business Name
- Gibson Green Electrical
Lucien... I think you should do ½ day sessions (a full day would blow your mind !)... "Playing with stuff with Lucien"... you could easily charge say £90 ish I reckon ! I'll put my name down. Would be popular around fathers day too maybe ?
(remember where you heard it first... only 5% commission per booking)
(remember where you heard it first... only 5% commission per booking)
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Lucien Nunes
Ha, one of my mentors used to do something similar, workshop sessions for you to fix your stuff under his guidance, not unlike today's local repair workshop / maker shop scene, 20 years before that became a thing.
But anyone who wants to play with electrical and electronic things can come and help with setting up museum exhibits and it doesn't cost a bean. Physical abilities permitting you are likely to get drafted in to help with lift'n'shift too though, it's not all joining-up wires and twiddling dials. Next week for example Dave and I have 15 display cabinets to collect that need to be carried down a flight of stairs. The main action takes place in the N. London / Herts / Beds areas. We have pallet racking to put up and a stage to build. Machine tools to move and woodworm to treat.
The iron is hot and the cement mixer is running. Cast iron does not levitate without assistance.
But anyone who wants to play with electrical and electronic things can come and help with setting up museum exhibits and it doesn't cost a bean. Physical abilities permitting you are likely to get drafted in to help with lift'n'shift too though, it's not all joining-up wires and twiddling dials. Next week for example Dave and I have 15 display cabinets to collect that need to be carried down a flight of stairs. The main action takes place in the N. London / Herts / Beds areas. We have pallet racking to put up and a stage to build. Machine tools to move and woodworm to treat.
The iron is hot and the cement mixer is running. Cast iron does not levitate without assistance.
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