2009


Have you got a sluggish crystal that doesn't key too well?

This can happen and does not mean the crystal is faulty. Some crystals just will not key quickly. If you improve the feedback in the PA then you should be able to get even the most reluctant crystal to key fairly well. There are two Paraset pa circuits around so read below carefully and select the best method for your type of Paraset.

If your Paraset has an r.f. choke in the cathode then do this:

Connect a low value capacitor between the grid 1 (pin 5) and the cathode (pin 8) of the pa. Somewhere between 5 and 15pf should do nicely. You could use a gimmick insulated wire twist capacitor about 1" to 2" long. Or a square of double sided pcb about 5/8" square as the capacitor plates. Don't use a low voltage rating capacitor here as there are quite a few volts flying about, you could use a silver mica capacitor here as that would survive.

If your Paraset has a resistor in the cathode then do this:

Connect a low value capacitor between the anode (pin 3) and the grid (pin 5) of the pa. Somewhere around 2 to 5pf should do nicely. The best and most simplest way is to use a gimmick insulated wire twist capacitor about 1" long. One could use a square of double sided pcb about 3/8" square as the capacitor plates. Don't use a low voltage rating capacitor here as there are quite a few volts flying about, you could use a silver mica capacitor here as that would survive.