Years ago when changing the frequency of a transmitter meant swapping out a crystal, amateur operators kept a box of crystals handy so they could swap out on the fly. These days, most operators don't have a box of crystals handy. Those of us who enjoy tinkering with older technology radios often will acquire a radio that once had a crystal in it, but those have long since disappeared, and all that is left is two holes where the crystal once lived.
These images were taken from order forms and and a catalog sheet from JAN Crystals of Ft. Meyers, FL in 1973. CB crystals were $2.50 each, and 2 meter FM crystals were $3.75 each. Amateur radio crystals for the HF bands were 75 cents each, or three for $2.00. Shipping was 10 cents per crystal (parcel post) or 15 cents per crystal (First Class).
These images will provide the dimensions and wire spacing for the most popular crystal holders (mounts), so if you end up needing a crystal for a Lafayette 6 Meter Band Transceiver (I'm looking at one on the bench right now), a quick measurement will tell you the wires are a 1/2" apart, so the crystal holder is either an HC6 or an HC17. The HC17 wires are longer than the HC6, so a quick measure of the length should identify the crystal holder number easily. The actual crystal would have a number selected by the manufacturer (such as CR-18/U, or 211-10T), which may or may not mean much to you. But, if you can identify the holder number and frequency of the crystal, you should be able to order the correct replacement.
Crystal frequencies were usually marked as KC, MC, or MHz, so pay close attention to how the frequency is identified. 6444 KC is the same as 6.444 MC, and it's easy to misread the tiny stamping on the end of the crystal. (Side note: "Crystal" is often abbreviated as "xtal".)
There are more crystals and holders out there than the ones shown here, but these were the most popular amateur radio crystals of the time. If I find more comparison graphics, I'll add them at that time.
