Cryptic Alignment Instructions.

[Les Dickson]

I’ve just finished the electronics on an RCA Victor Model T4-2 and it’s functioning quite well. However, I’d like to tweak the alignment but I don’t understand the cryptic alignment instructions. All it says is
R.F. 1400 KC
IF 460 KC
Peak All Stages

Attachments:

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   rca-t4-2-schematic.gif
   

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   Resized_20200915_194211.jpg
   

[Alistair Thomson]

I have to make some assumptions here, because I don’t know what this radio looks like inside:

1. L2 and C1/C2 tune the frequency being received;
2. L3 and C6/C5 tune the oscillator frequency.;
3. C1 and C6 are ganged so that the oscillator tracks the received frequency giving an IF of 460KHz into L5/L6;
4. All heaters are connected in parallel.

If that is all the case, I would first peak the IF by removing Tube 1 and injecting 460KHz from a signal generator into the L5/L6 transformer via a loosely coupled coil, peaking with C9. Peaking could be by oscilloscope or simply by audio level.

Then I would insert tube 1, tune the dial to 1400KHz and inject 1400KHz into the antenna, again via a coupled coil, to L11. I would then peak that signal with C2, then peak it again with C5, and again with C8.

Of course, this might all be rubbish!

• This reply was modified 5 years, 5 months ago by Alistair Thomson.

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