I there any focus gain in using 3 22 meg resistors in series to make 66 meg or would it be the same as using a single 66 meg stick resistor.

Not really, other than improved HV creepage and clearance handling perhaps, the specialty 66m 6kv resistor will do fine as it was made for just that application, the only reason that early color sets had 3 22m resistors was that they had not created the specialty 66m one at the time and was not in mass production as it was later.

the 1963 silvertone I had with the ctc12 clone had the stick resistor unless Motorola decided to keep using 3 resistors maybe they didn’t trust the new stick resistor.

did you ever do the heater voltage tests?

Or they just had a HUGE stock of 22m 6k resistors on hand! :D

Or, at the time, they could buy three 22M for less than one 66M.

I didn’t do the heater voltage test yet

Not in St Louis.

I worked in the EJ Korvette in Catonsville (Baltimore), MD right out of right school. I worked in the Audio Department. The only repair facility was in our Audio Department and it was only for the equipment that we sold in that department. Televisions were in the department next to us. And remember how color sets were always in a darkened room?

Zenith 21FJP22 tubes
 

Years ago in working with Zenith TV's I came across a Zenith roundie with a CRT that had a Zenith brand sticker/label on the top of a RCA label. They were either too lazy or didn't care.

[QUOTE=Electronic M;3253618]Zenith/rauland made their own, RCA did, and so did Sylvania. Easiest way to know who REALLY made a tube is to look up the EIA number on the label. I've seen Zenith labeled roundy tubes that had Zenith, Rauland (Zenith subsidiary) and RCA EIA codes. The RCA tube appeared to be early into Zenith selling roundys.


Many years ago the CRT's were in somewhat short supply. If you made your own tubes you were in the drivers' seat for making as many sets as you wanted. Smaller manufacturers had to depend on what ever they could get ie; Curtis Mathis and others like them. Yes, they also traded around as in contract marketing. Smaller vacuum tubes were also treated and traded the same way.

Gun booster
 

Anyone know how these work I have used one in the past but don’t know how this works by boosting the gun but does not change heater voltage. They do work good without changing the heater voltage.

Are you sure? I can't imagine how that's possible.

I did post the same question years ago but don’t remember the result. I think it was taking voltage from somewhere else within the plug there is an adjusting pot and no transformer inside since I took one apart befor and all there is inside is a resistor and a pot.

I'm not sure which one you got and opened, but the way that most work is on 2 levels, first is by boosting heater voltage from 6.3 to at least a volt or more higher via a transformer in most cases, second is by isolation which may sometimes help in H-K shorts.

These brighteners came red green and blue depending on what gun is weak the pic is for the red gun they are colored. I had taken a green one apart and the heater connection is not touched at all just wires from the gun that will be boosted to a resistor and a pot that’s it

I'm unfamiliar with how those type might work, never having seen one, they must be trying to alter the bias of the “weak” gun in relation to the others to try and balance things out, but I can't imagine that working out so well vs a real booster that kicks up the heater voltage, which is only a Band-Aid to start with.

I used one on another set with a really weak red gun could not get a white screen not enough red but after plugging one of these in it never changed the green and blue adjustment only the red just turned the pot up alittle and viola had more the enough of red. It is odd not to increase the heater voltage but it don’t but they do work well.

It has a pot that is accessible for adjustment (not visible in the photo)? Must be changing the G2 range on the affected gun.

The only thing I think it may have been doing is altering the cathode bias beyond the standard ranges on the tube for the weak gun, and thus pushing the drive level even harder, but that can't be very good for a weak gun on a tube, likely to burn it up fast.

It seems to me changing the G2 on one gun could get the mid grays about right, but the tracking would be poor. I really would like to have seen one in operation.

Someone here years back had mentioned that some voltage is changed with this maybe how it’s wired like maybe the G2 The post is here somewhere but it was awhile ago. They still show up on eBay sometimes and this has a 7 meg pot and a high ohm resistor

Another thought is that if it's adjusting the cathode drives, since it's passive, it can only reduce them, so the correction would be at the expense of reduced brightness.

I do know with the red all but almost gone after plugging this in the red was really strong

I remember setting up this set and the red gun pot was maxed and bearly able to see the red that was there.

Well w/o seeing it, we can only guess at how it worked. :./

I have one for red and one for green but I don’t need either one thankfully.

Well, if you have 2, why not post detailed pix of them to help us understand how the work?:yes:

Do you mean take one apart ? The pic I posted just don’t show the pot

Yes, if available.
Also the one you posted is not very clear, it would help if it was higher definition, and all markings / words written on it could be seen to help ID it, cause it's kinda blurry and partial, looks like “Colorite” or something.
There are also other numbers on it, can't tell what they are, or if they mean anything at all.

This one is the same all three just got to get it apart

That thing seems to be a mystery device, can find no info on them at all, but lots on the normal heater type boosters.

This is odd it just looks like the pot and resistor is wired in series with the two green wires from the plug.

This looks like it’s in series but I don’t see anything that ties in for extra voltage

which ones on the socket??

I suspect it's on pins 4 ,13 or 5, depending on what ever color it was made for.

Those types of "boosters" were advertised in a lot of the electronic magazines back in the day. The most basic ones came with splice connectors to use on which ever gun needed it. It's just a pot and limiting resistor connected between the screen and grid of the gun.

This brightened is for the green gun so there is solid green and green and white the solid green goes to center of pot and the green and white goes to a resistor and soldered to one end of the pot and both go out to the tube.

I found the basic patent with a schematic:
https://patents.google.com/patent/US4139861

The idea is to reduce the negative g1-cathode bias, increasing the current in the gun (but also ruining the lowlight tracking, which is then restored by adjusting the cutoff with the set's G2 controls).

edit, Ahhh so my first thought was right!
Lower the cathode voltage a bit! :P