21AXP22 Vs 21FJP22

[Electronic M]

I've got all 3 as well as FJP, GUP/GVP types and some of the late size measurement/labeling rule change roundy tubes with 19V numbers.
All are capable of good pictures.
The 21AXP22 is a better tube color wise (early ones in the 21CT55 and CTC-4 had the same NTSC spec phosphors as the 15GP22. The CTC-5 is the muntz/portacolor of RCA color chassis (the low point where they cost reduced the design too much and had to back track during and after it) and can't really drive the AXP to correct HV spec...It also lacks full DC restoration. The right set to see an AXP working to its potential in is a 21CT55 or a CBS 205.

Makers were continually changing phosphor blend until settling on SMPTE in the late 60s. Different 21FBP22s from different makers (RCA, Zenith/Rauland, Sylvania, etc.) had different phosphors with different primary gamut, brightness, and phosphor power down color.
Some FBPs had green-ish phosphors, some had white phosphors, some had grey. There were also green, and black tinted safety glasses that could change the look.

The Demodulator circuit (its health), greyscale and setup all play a role in how good or bad a CRT looks.
I currently own working examples of every RCA consumer color chassis except the CTC-12, an RCA TM-21 broadcast monitor, a conrac CYB21 broadcast monitor, I've had every year of Zenith roundy (I currently keep J, M and N years), I've got rare 50s colors from a variety of makes and rare 60s roundys from a variety of makes...Easily over 25 roundys. I've seen different year RCA chassis make different pictures with the same tube swapped between chassis, I've seen a great tube swapped to a mediocre chassis make a mediocre picture.

Performance is a function of good combination, circuit performance, and setup. If you go long enough in the hobby you'll see AXP sets and FBP sets that make some CYP sets look bad. Heck my CTC-9 had me thinking the CYP was an ugly pastel looking tube, but my CTC-10 and low hours CTC-7 make it look good.

When you hit a good combination treasure it.

The Europeans chide it as Never Twice the Same Color and with the constant changes to Demodulator circuits/angles, station camera and modulator adjustment practices, and CRT phosphor over the 50s and 60s, they weren't wrong.

[old_tv_nut]

Originally Posted by Electronic M

I've got all 3...

...Performance is a function of good combination, circuit performance, and setup. If you go long enough in the hobby you'll see AXP sets and FBP sets that make some CYP sets look bad. Heck my CTC-9 had me thinking the CYP was an ugly pastel looking tube, but my CTC-10 and low hours CTC-7 make it look good.

When you hit a good combination treasure it.

The Europeans chide it as Never Twice the Same Color and with the constant changes to Demodulator circuits/angles, station camera and modulator adjustment practices, and CRT phosphor over the 50s and 60s, they weren't wrong.

Thanks. This is the best summary I've seen of the wild, wild west nature of NTSC over the years. Don't forget the NTSC black level of 7.5 IRE that had no explicit reference in the signal, the extreme variability of that, chroma level and burst phase that occurred in analog cable systems, all contributing to inconsistency.