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Old 02-14-2017, 04:55 PM
Kawooa's Avatar
Kawooa Kawooa is offline
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Join Date: Aug 2015
Location: Wyoming.
Posts: 36
B&K CRT 400 reads lower then 465

I have a CRT 400 which I replaced all bad resistors in and the selinum recitifer. A new silicon diode is in series with a 5w 200ohm resistor for roughly the same voltage drop as orginal. My 465 is also partly restored up. There are a couple resistors I need to check but everything else seems fine. I replaced the capacitors in both.

When I test a 17BP4? on the 400 it glows the two half of the neon lamps for no shorts dimly. On emission it will only read 150-200 at best. I even tried two other 6X4 tubes in it to no avail. My 465 reads no shorts as well but on emission it reads 450-500ua. I did hit the tube with the rejuv. low using the 400 as the emission was quite low. Before the rejuv. The 465 would read about 200-300ua. I left the tube on the 465 for an hour and the reading increased slightly.

I want to know why my 400 reads so much lower then the 465. I did calibrate the heater voltage on the 465 meter to exactly dead on when using 117vac as per the manual. I will check the 400's heater voltage at some point but since it's a set voltage for then grids I haven't been comfortable enough to handle the connector.

This all started when I decided to test a 5DEP31 tube from a busted heathkit oscilloscope. The tube shows no emission at all! I tried repairing open elements but nothing worked. I think it's a different pin out even though it uses the same connector. So I tried both testers and same result. So I tried them on my 17BP4 to be sure it was the tube and not my testers. The 465 was set to read the heater voltage a little low so 6.3v on the meter was really 6.5v. So before I rejuv the reading was about 200-300ua. After rejuv it reliably shows 460ish ua.

And on the 465 cutoff is fantastic at just over 25v G1. The setup chart states 22-77v G1. So right now I'm more inclined to believe the 465 is accurate or at least close. But somethings off with the 400 as it reads much to low for me to pass. If it was within 50 I'd be fine.i want to solve this before I try to sell as I don't need it. Pm me if you want it. Otherwise eBay it goes.

Thanks for the help
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