Hickok 752A calibration? - Page 5

mksj100 · 7th January 2012, 10:57 PM

Pretty stiff on the transformer rewind, but then it is a lot of work and time. Another option might be to use/fit a toroidal transformer that has dual independent secondaries. You would need to account for the primary side voltage which I assume it is 100V on this model. AnTek has a number of inexpensive dual voltage dual isolated secondary windings toroid transformers. Something like the AN1T200 ($29.00), would give ~203V unloaded at 120V, so ~170V at 100V input (both secondaries would be used independently as opposed to parallel) Antek - AN-1T200 . Toroid transformers would be a bit stiffer, so may not see as much sag under load, but you could always pad it on the primary side. Not sure how it would operate in the tube tester circuit, but I have done something similar on the filament transformer to allow testing of some high current tubes. It's been an informative discussion, will bow out at this point.

dgta · 11:24 PM

Guys, looks like I can get an Antek transformer with TWO 170V secondaries pretty cheaply but need to be careful specifying it.

Can anyone tell me how much the plate voltage (150VDC) droops with an actual tube under test drawing current? For example, a 6L6 at whatever the test current is (20-30 mA?)

Edit: wow, I was just researching Antek while you were posting, how coincidental can we get?

7th January 2012, 11:21 PM	#42
dgta diyAudio Member Join Date: May 2011	Guys, looks like I can get an Antek transformer with TWO 170V secondaries pretty cheaply but need to be careful specifying it. Can anyone tell me how much the plate voltage (150VDC) droops with an actual tube under test drawing current? For example, a 6L6 at whatever the test current is (20-30 mA?) Edit: wow, I was just researching Antek while you were posting, how coincidental can we get? Last edited by dgta; 7th January 2012 at 11:24 PM.

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7th January 2012, 10:57 PM	#41
mksj100 diyAudio Member Join Date: Oct 2007 Location: Tucson, AZ	Pretty stiff on the transformer rewind, but then it is a lot of work and time. Another option might be to use/fit a toroidal transformer that has dual independent secondaries. You would need to account for the primary side voltage which I assume it is 100V on this model. AnTek has a number of inexpensive dual voltage dual isolated secondary windings toroid transformers. Something like the AN1T200 ($29.00), would give ~203V unloaded at 120V, so ~170V at 100V input (both secondaries would be used independently as opposed to parallel) Antek - AN-1T200 . Toroid transformers would be a bit stiffer, so may not see as much sag under load, but you could always pad it on the primary side. Not sure how it would operate in the tube tester circuit, but I have done something similar on the filament transformer to allow testing of some high current tubes. It's been an informative discussion, will bow out at this point.