RADIO TUNERS

[alg2468]

I have two radios that have analog tuning with a digital frequency readout: a General Electric World Monitor Radio (model 7-2990) and a Kchibo 10 band AM/FM/SW radio. The frequency readout is a great help in tuning radio stations. Why are not most radios sold with a digital frequency readout? Surprizing considering that digital tuning became practically an industry standard for TV's by the late 80's. Does it really add a lot to a portable radio's cost to add a digital frequency readout?

 

[rbrucecarter5]

Several issues -
(1) power consumption. There are low power chip sets available, but all that digital circuitry does drink power.
(2) noise - it takes careful design to keep digital noise out of the RF chain. A lot of consumer gear doesn't even try, and it doesn't matter because the sensitivity isn't there.
(3) offset tuning. It is nice to be able to choose to offset the tuning on AM a bit to get rid of adjacents. Can't do that with digital unless it has 1 khz steps. And that is a pain, too, because then you have to tune and tune to get anywhere.

Again, there are fixes for all of these, but the reference designs for most cheap radios consist of:
One IC - AM/FM receiver on chip
4 gang tuning capacitor
ferrite loopstick antenna for AM
one ceramic filter each for AM and FM
discriminator coil for FM or ceramic discriminator.
Add the audio circuitry and off you go. Cheap parts list. If you add digital tuning, you add a lot to the materials cost.