Since you mention “5U4s”, I have always wondered, is there really a big dif in the 5U4/5U4G/5U4GB, and so on.
This site seems to list differences, but does it matter in a TV?
https://300guitars.com/articles/rect...ge-drop-chart/
My set has the OEM RCA 5U4-Gs, they still work but are old and a bit worn, I can see a bit of the heater material has come off and is floating around in the tube, to get EXACT replacements will hurt a lot cause of the insane prices they want for them, thanks to the audiophile market.
$170 for a NOS RCA 5U4-G is insane!
The GB has a larger voltage drop, 6-7 volts and has a much less crazy price, will that drop of 6-7 volts in the G vs the GB really matter much?
The GZ37 has an even better voltage drop rate at 37v, but it's price is even MORE insane for NOS, WTF!
And there is also the 5AR4 / GZ-34 , not so over priced, but with a voltage drop rate of 10v, may be too harsh.
So it seems is is 5U4-G and pay, and pay A LOT for them, or 5U4-GB, and have slightly lower voltages.
To me it makes no sense for the prices to be so damn high.