Here are my recommendations, and the article below explains why.
IF YOUR BUDGET IS AROUND $30, get a Korg CA-40 and a direct-connect cord.
But if you POSSIBLY CAN SPEND $79, get a Dusty Strings Dulci-Tune!
If you follow the tuning tips listed below in a very quiet room, almost every tuner will work pretty well. But you can't always tune in a very quiet room. Sometimes you are at a noisy workshop or jam, and others are tuning, playing, and practicing, and your tuner goes crazy! It's almost impossible to tune because your tuner hears sympathetic vibrations on your instrument, plus all the other instruments in the room, and it doesn't know what it is supposed to be tuning!
The answer is to use a tuner that connects directly to one of the tuning pins on your dulcimer. Almost all other sounds except the strings on your dulcimer are virtually ignored, and tuning is SO MUCH easier!
There are lots of tuners that accept 1/4" plugs on chords that you can clip on to a tuning pin. The best quaility for the price, in my opinion, is the KORG CA-40, with a cord. You can order both for $30 by clicking on DULCIMER SHOP above, and then clicking TUNERS.
But if you can possibly swing $79, the Dusty Strings Dulci-Tune is a must-have! It slips snugly onto a tuning pin, eliminating the need for a cord. And it works better than any electronic tuner I have ever used (unless you want to spend hundreds of dollars on a strobe tuner, and take two hours tuning!). You can order a Dulci-Tune by clicking DULCIMER SHOP above.
TIPS ON TUNING
1. When tuning the bottom string of a course, use your middle finger to lightly touch the top string to deaden it so it will not vibrate while you pluck the bottom string with the fingernail of your pointing finger. When tuning the top string of a course, use your thumb to deaden the bottom string.
2. Pluck the string you are tuning as SOFTLY as possible. Begin by barely plucking the string. If your tuner is not picking it up, pluck just a tiny bit harder until the tuner picks it up. The softer you pluck, the better the tuner works. This is because plucking softly does not make other strings vibrate.
3. When tuning treble-bridge courses, tune the strings on the side of the treble bridge that is nearest the tuning pin. Tune 1/2 tone above the desired pitch, then gradually tune back down until the note is in tune. This will almost always result in the note on the other side of the treble bridge being in tune.