Ok. Let’s try this again…RCA 9TC240 Alignment

[Penthode]

Could you show us a photo of the tool you are using to adjust the slugs?

[Chris K]

Originally Posted by Penthode

Could you show us a photo of the tool you are using to adjust the slugs?

Both are plastic tools

[Chris K]

I found another core to go in to possibly work as a secondary in the trap but it's longer than the original core for T-103. Could that possible work?

[Chris K]

Could this possibly work as a substitute? It's 21.25mc primary and 21.8mc secondary trap.

[Penthode]

What is the Merit no.? Looks like TV-107? If it is specified as an RCA replacement maybe.

[Penthode]

I looked up TV-107. It is listed as a convertor transformer with the sound take off similar to the RCA transformer. It was likely used on full split sound sets with sound take off at the convertor. One thing I feel is the trap of the origial spread out on the bakelite frame will have a higher Q. It means that the trap in the RCA provides a deeper null. This may be important when adjust the bandwidth with the 22.1 marker. It means that you may need to modify the alignment procedure to narrow the video IF bandwidth slightly to reduce sufficiently audio carrier passing the remaining video IF stages. Although there is a second 21.25 MHz trap down stream. It is a flip.

It can be made to work but I would prefer the originality.

[Chris K]

I agree but if I cannot save these coils, I'm not sure originality can be at the top of the priority list. Silly question next...I do have an RCA 630 spare parts chassis. The traps are of a different form factor but they will fit the chassis mounting holes. They would be able to make the adjustments for this KCS 28 chassis I think. Thoughts from anyone?

[Penthode]

The coil you are replacing T103 is a combined video stagger tuned stage and sound take of at the trap. The 630TS chassis is of an earlier generation and it is not compatible.

[Chris K]

Originally Posted by Penthode

The coil you are replacing T103 is a combined video stagger tuned stage and sound take of at the trap. The 630TS chassis is of an earlier generation and it is not compatible.

Got it. If you could give me an opinion of an earlier question? I have found another threaded core (ferrite I imagine?) but it's about 1/8th" longer than the core I broke. Do you think that core might work adequately enough to give it a try?

[Yamamaya42]

Originally Posted by Penthode

The coil you are replacing T103 is a combined video stagger tuned stage and sound take of at the trap. The 630TS chassis is of an earlier generation and it is not compatible.

So this is sort of a early Intercarrier type set?
Tapping off audio at the 3rd IF it looks like.

[Penthode]

Originally Posted by Yamamaya42

So this is sort of a early Intercarrier type set?
Tapping off audio at the 3rd IF it looks like.

RCA did not begin using the intercarrier design until about 1951-52.

No the sound take off is still before the video detector, hence split sound. The idea was to suppress the sound carrier as much as possible prior to the video detector to prevent a 4.5MHz carrier beat. The factor being this set has a wider video bandwidth set compared to most others and the the baseband video response is beyond 4MHz in this set making a 4.5MHz beat more visable.

This chassis hower does take advantage of the first two stages of amplification to provide extra gain.

[Yamamaya42]

It's a bit confusing to me what is and what is not!

Cause i see early BW sets with it pulled off after the video detector, and also color sets 45.75mh/41.25mh with it tapped from the 3rd IF before the video detector.

[Penthode]

Originally Posted by Yamamaya42

It's a bit confusing to me what is and what is not!

Cause i see early BW sets with it pulled off after the video detector, and also color sets 45.75mh/41.25mh with it tapped from the 3rd IF before the video detector.

Colour sets pull the sound off before the video detector to minimize the 4.5MHz beat. You will also notice colour sets have another detector after the 3rd IF which is in effect an intercarrier mixer to extract the intercarrier sound.

The intercarrier sound process was desirable because the audio is available over a wide range of the fine tuning control. In otherwords with intercarrier sets you can fine tune for best picture and not worry about the sound. Split sound sets the tuning is for best sound. Which means the Video IF alignment for split sound sets is more critical because if the video carrier is not EXACTLY at 45% on the nyquist slope on the IF resesponse when the sound is 21.25MHz for the spit sound IF channel, the picture will either be soft or excessively noisy.

[bandersen]

You want these black coils - right?

[Chris K]

OMG yes! You are The Man!