To getter the tubes,? you can use the lower B+ position, apply a bit of drive ( with amp into a DL), then tweak the tune cap off resonance a bit.? ?That's from W8JI.?
Another method is to use a small lab supply, with positive terminal to chassis...and negative to cathode...and apply some vdc.? ?That will bias the tubes on....and plate current can be dialed up to anything you want.? ?This is with amp keyed on, NO drive applied...and drawing idle current.? ?With the small lab supply,? you can dial up any amount of idle current you want.? Again, use the lower B+ setting.? ?This method will work? with B+ as low as 900 vdc.?
On a good eimac 3-500Z, they will hi-pot test 16 kv from anode to grid...... and 5 kv from grid to cathode.?
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On the chinese 3-500Z's, they hi pot test 1 kv? between grid and cathode, normal for chinese 3-500Z's.? The chinese 3-500Z's also have a lot higher grid to cathode C? vs an Eimac.? The chinese tubes have the grid a lot closer to the cathode vs an eimac.? Grid to cathode shorts typ show up when the? cathode is lit.... and results in negative grid current on idle. ( on RX), and tube biased off.?
