[earlyfilm]

The other suggestions have been good, but first, let's stop and plan the project.

I am going to suggest a logical method for thinking this through, parts of which you have already done.

Per Sams, the Admiral uses a 12LP4, which is a an magnetic focused CRT and you want to replace it with a similar CRT and you do not know what the CRT in the potential donor set is.

First, see if there is a tube chart in the set to be junked. These charts are not always where you expect them to be.

Second, and this took about two minutes to do on the internet, look up the donor set service data and you quickly will see that Rider 6-41 has the schematic, Sams Servicer in folder 556 has servicing information on this set and a similar model number 2D2047B has a schematic in Sams 161-10. The Truetone uses chassis number 12AX27, if Rider is correct. Is that number on your donor chassis?

Third Look at the potential donor CRT and see if it has a number. Sometimes they are high enough on the neck to be under the yoke. Do NOT clean the neck and base yet, and use a point-source flash light to see if a faint number is visible. If none if found. Gently clean the neck with a soft brush. Look again. Sometimes if you can make out a partial number, blowing your breath on the number, to make the neck fog, which can bring it out.

The last resort is to use liquid cleaner the neck, taking care not to get any in the base to glass joint. If the number was in ink, it will be gone, but if it was acid etched, a flashlight and/or a light dusting with talcum powder will bring out a number.

If the CRT is a rebuilt as indicated by a less than perfect neck weld, often times one will find a substitute gun in the CRT, with the most common error being a bent gun in an aluminized CRT and on a non-aluminized CRT the bend angle is different, which requires a different strength magnet, which may be the case on the donor CRT.

You already have said you have measured the CRT and it is close but not quite the same. Does the angle of the bulb indicate it is the same sweep deflection angle? Does it have the same base? Is it magnetically focused like the 12LP4 or electrostatically focused? You should have a schematic (there is one on ETF) for the Admiral that you going to restore, and you have mentioned the set to be junked is working, so on the donor set, gently slide the CRT socket out and take voltages and see if they are close.

James