1951 Zenith 16" Porthole

[John Marinello]

Originally Posted by dieseljeep

The set uses the old 52 degree 16EP4, not the newer 16GP4 70 degree CRT.

Wrong, x2.

24H20 chassis use the 16GP4.

The 16EP4 is a 60 degree tube.

[Radiotronman]

The picture us a little dim, but if you look on the upper right hand if my cabinet tube layout, it lists the 16GP4 for both 24H20 and 24H21 chassis. The schematic for this set (SAMs 120-13) also list it for the 16GP4.

[John Marinello]

Originally Posted by Radiotronman

The picture us a little dim, but if you look on the upper right hand if my cabinet tube layout, it lists the 16GP4 for both 24H20 and 24H21 chassis. The schematic for this set (SAMs 120-13) also list it for the 16GP4.

That's just a tube layout, and covers the 24H20 (16") & 24H21 (19") chassis,
which were similar. If you look at the CRT, It shows 16GP4 OR 19AP4.

The 16GP4 is a 70 degree tube, and the 19AP4 is a 66 degree tube.

[Radiotronman]

Finally got around to placing my order for capacitors and decided to recoat the flyback and clean the dust inside the cage area. The flyback had pieces of the original coating laying at the bottom which I removed. I recoated it with rtv sealant and I'll reinstall the casing once it cures over night.

[Radiotronman]

Surprisingly, there was also a wire on the flyback that wasn't even soldered on! It was just wrapped around the loop connector. So I cleaned the terminal and soldered it on. I don't know how it worked all these years without a secure connection? It was loose when I touched, just floating.

[Radiotronman]

Just an update after most of the recapping is done. The hv is low, but I do have a raster with a picture!

[John Marinello]

What is your HV reading? Not sure what to make of your pic, is it just dim, or blurry also? What happens when you increase brightness, does the pic bloom, then extinguish? That would be a symptom of low HV. Is your ion trap adjusted properly?

[dieseljeep]

Originally Posted by John Marinello

Wrong, x2.

24H20 chassis use the 16GP4.

The 16EP4 is a 60 degree tube.

If I'm going to be wrong, I do a good job of it!
I looked at the Riders #6 coverage for that chassis and it looks like it was the last run of the portholes. They did have to switch to a 70 degree sweep to incorporate the 16 and 19" CRT.