Radio technology is ever changing. Whether that is good or bad is really up to the individual. I like to think that change can be good if it serves a purpose. However, I am often opposed to change just for the sake of change. That includes unnecessary changes in technology.
Many old timers remember the days of the big dial on the VFO (Variable Frequency Oscillator). This dial, or knob, was connected to a genuine variable capacitor. As you turned the knob/dial, the capacitance within the capacitor would change. This change in capacitance corresponds to a subsequent change in the frequency the radio was tuned to, thus it would vary accordingly. This is why we called it a VFO. Today, many so-called “VFO’s” are really just optoisolator circuits, meaning that when you turn that know, it simply changes where light hits a photo-conductor.
Want to know whether or not your radio is using a real VFO or an optoisolator? Turn the dial while the radio is off, and then turn it on. If the frequency is unchanged, it is an optoisolator. If it changes, it is a real VFO.
What about volume control? Pretty much the same thing. However, in older radios, volume is handled by a potentiometer (basically a variable resistor). As the resistance is decreased, the volume in your speakers increase. Just like the VFO, many modern radios also use an optoisolator for volume control. Thus, it should be obvious that the same test would apply. To know if it is a real potentiometer, or an optoisolator, turn off the radio, spin the knob, and then turn it on. A change in volume should indicate that it is the real deal.
There is something I should say about optoisolators versus a genuine variable capacitor, or potentiometer, and how they work. Maybe it will be obvious to some of the older guys, but many young guys might not get it. There is a definitive difference in how an optoisolator feels versus either the VFO, or a potentiometer. With an optoisolator, you can feel something to the effect of clicking. With both the VFO and potentiometer, there is a certain level of positive resistance when turning the knob that controls them. Optoisolators don’t have that resistance. Thus, you should be able to tell, based entirely upon feel, if your radio has the real deal, or just a digital fake.
Maybe it is just me, but I prefer the real deal. Yes, it does take up more physical space, but it is less likely to fail. Perhaps that is the true beauty of older radios, they aren’t as likely to fail, as they are not reliant upon computer parts. Yes, I am being a bit of a curmudgeon, but sometimes I have to.
Changes in radio technology can be good. I don’t necessarily mind an HT using digital circuitry. However, for a good base station, I’d prefer a genuine VFO and potentiometer, as an optoisolator just won’t cut it. Digital does have a place in the ham shack, but does it really need to be part of the radio? I would like to think not. However, I leave that to the discernment of the reader.