Most DMMs have 10Meg input impedance, so you can put a 10meg resistor
in-series with your meter, and measure double the voltage. It wont be
exact, but pretty close. If you really need an exact measurement, then
measure a stable lower voltage without the resistor, then again with it.
Dividing
Thanks everyone for the hints, I'll look more closely at the HV - I'm a bit
shy about measuring as I don't have a meter that will go to -1300v for the
bright.
- Gary
On Tuesday, October 26, 2021 at 3:17:49 PM UTC-4 Bartek Ogryz wrote:
> I'm not familiar with that project and that circuit, but
I knew I'd seen the number, and found them just now:
http://www.tube-tester.com/sites/nixie/dat_arch/Numitron_RCA_01.pdf at the
bottom of the page, they are development numbers for the DR2200 series.
/Martin
On Tuesday, 26 October 2021 at 22:21:47 UTC+2 Dekatron42 wrote:
> Tubes designated
Tubes designated DTF are development numbers used by Apollo/RCA - it says
so at the bottom of their datasheets.
/Martin
On Tuesday, 26 October 2021 at 21:43:52 UTC+2 Bartek Ogryz wrote:
> Hi!
> They appeared on eBay last days: DTF137, DTF138, DTF140 (or maybe DTF/37,
> DTF/38, DTF/40). What
Hi!
They appeared on eBay last days: DTF137, DTF138, DTF140 (or maybe DTF/37,
DTF/38, DTF/40). What are theese? Anyone has some more knowledge about them?
Bartek.
BTW: If someone is interested in numitrons, quite rare Apollo DA-2500 are
hiding on eBay: item no 254866404573. Unfortunatelly, as
I'm not familiar with that project and that circuit, but based on my
experience in CRT TV repairs, if you have a proper blanking signal,
something must be wrong with HV as Tristan said.
Grid1 - negative voltage on this grid allows electrons to flow (brighter
picture), 0V blocks them (darkness).
