11-11-2014, 04:56 PM
Alignment is making the adjustments so that the tuned circuits in the radio are all tuned to the proper frequencies, and in the correct relation to one another. In your radio there are a good many adjustment screws that you should be able to see. Most, if not all, of these are adjustable capacitors, known variously as compensators, trimmers, or padders.
The alignment does a few things:
1) It makes sure the circuits tuned to the intermediate frequency (IF) are all tuned identically, so you get the maximum throughput. Your radio is designed for an IF of 470 kilo hertz (also called kilo cycles). If both your IF transformer circuits are not tuned identically, your volume will be low.
2) It makes sure the dial is adjusted so that the dial pointer is pointing to the right frequency all the way across the dial. If you are listening to a station at, say, 850, you want the dial to point to 850. If this is adjusted wrong, not only will the dial point to the wrong frequency, but you might lose stations at each end.
Usually, alignment is done by injecting known modulated frequencies into the radio with an instrument called a signal generator, and adjusting the compensators to those known frequencies. Often you have to re-do the adjustments several times.
Alignment of the AM band can be done to a fairly good approximation without a signal generator if it isn't too far out of adjustment when you start out. To do this, you use strong local stations that are close to the frequencies that you would use if you had a signal generator. There are some pitfalls to doing it this way. A signal generator makes it a good bit easier.
If you adjust the IF this way, you will almost certainly not be able to tune the IF to 470 KHz, but you can get the IF circuits tuned to the same frequency as each other. That is almost as good, as long as they aren't too far away from 470.
The same procedure can be used with police and short wave bands, but it is a lot harder to find broadcasts close to the frequencies you need, and to be sure what the actual frequencies of the broadcasts are.
Because your radio is a fairly complicated one with many compensators, I'd advise using a signal generator and getting some help and advice the first time through. At least do some reading so you understand what you are trying to accomplish. After you do a couple of radios it is usually pretty easy, but I know my first few times through were kind of intimidating.
Most of the time your schematics will have alignment instructions along with pictures that show where the adjustments are.
The alignment does a few things:
1) It makes sure the circuits tuned to the intermediate frequency (IF) are all tuned identically, so you get the maximum throughput. Your radio is designed for an IF of 470 kilo hertz (also called kilo cycles). If both your IF transformer circuits are not tuned identically, your volume will be low.
2) It makes sure the dial is adjusted so that the dial pointer is pointing to the right frequency all the way across the dial. If you are listening to a station at, say, 850, you want the dial to point to 850. If this is adjusted wrong, not only will the dial point to the wrong frequency, but you might lose stations at each end.
Usually, alignment is done by injecting known modulated frequencies into the radio with an instrument called a signal generator, and adjusting the compensators to those known frequencies. Often you have to re-do the adjustments several times.
Alignment of the AM band can be done to a fairly good approximation without a signal generator if it isn't too far out of adjustment when you start out. To do this, you use strong local stations that are close to the frequencies that you would use if you had a signal generator. There are some pitfalls to doing it this way. A signal generator makes it a good bit easier.
If you adjust the IF this way, you will almost certainly not be able to tune the IF to 470 KHz, but you can get the IF circuits tuned to the same frequency as each other. That is almost as good, as long as they aren't too far away from 470.
The same procedure can be used with police and short wave bands, but it is a lot harder to find broadcasts close to the frequencies you need, and to be sure what the actual frequencies of the broadcasts are.
Because your radio is a fairly complicated one with many compensators, I'd advise using a signal generator and getting some help and advice the first time through. At least do some reading so you understand what you are trying to accomplish. After you do a couple of radios it is usually pretty easy, but I know my first few times through were kind of intimidating.
Most of the time your schematics will have alignment instructions along with pictures that show where the adjustments are.
John Honeycutt
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