CT-100 Flybacks

I recently purchased a used CT-100 flyback. The numbers on it is 274406. I was told the RCA CT-100 flyback number which starts with 79 never appears on these parts. I compared this flyback to the one in my working CT-100. The number on my flyback is 274416. The number 1107355-1 also appears. I compared the various terminals on both flybacks and determined that the one I purchased had an extra terminal (#4) and it associated wire to the transformer as well as a transformer wire going to terminal #T and a 4.7K ohm resistor going to terminal #8 (no transformer wire on this terminal). My existing flyback has no terminal #4 and terminal #8 has the wire to the transformer and terminal #T is just a tie point for the 4.7K ohm resistor (the reverse of the one I purchased). The resistance of the flyback windings appear to be identical in both flybacks. If I were to wire the new flyback in my working CT-100 and reverse terminals #8 and #T I believe the one I just purchased would work.
I talked to another collector and the part number on his CT-100 flyback is 274410. Now we have three different flyback numbers. His terminals were wired the same as the flyback in my working CT-100. Apparently the flyback I just purchased is from a earlier CT-100 design. I also checked the schematic of my Model 5 and that has a HV doubler using three HV rectifier tubes so it uses a completely different flyback.
Any comments on why there are were so many versions of CT-100 flyback produced? We wonder if the last three numbers of the 274 number are not date codes (i.e. 274406 = 6th week of 1954?) and the number 1107355-1 is the real number for this part. I just found out that the number number 1107355-1 appears on two of the three flybacks (the third flyback has the second number unreadable) Wayne

Correction: My Model 5 has a Flyback transformer very similar to the CT-100. It is marked with number 274340. Part number 274 made in October of 1953.

[Don Lindsly]

The numbers beginning with 274XXX are the OEM number and date code. 274 was RCA's OEM number. The next digit is the last digit of the calendar year, 1954. The last two digits are the week of manufacture. Most parts were dated about a year ahead. I would not expect the numbers beginning with 274XXX to agree very often.

The 1107355-1 is the drawing number. That references the manufacturing data necessary to build the part.

There is a third number, usually shorter and beginning with 7, 9 or 10. That is the stock number. That number is used when ordering a replacement part from a supplier. That number is the one listed in Sams and the RCA service data.

The distributor usually had cross-reference lists that translated drawing numbers into stock numbers so if someone came in with a part in their hand, the parts person would know where to find it.

Don

[John Folsom]

Anybody out there have one of the cross references for RCA stock numbers to drawing numbers? I would be eager to buy a copy...

[Pete Deksnis]

For the record, there is no evidence that the part number for the flyback in a CT-100 changed during the production run. Part number 107355-1 appears on early and late production sets is spite of a production modification to the boost circuit.