Crystal saver for tube type transmitters

I recently had an email from a builder of a Pastime Projects “Remember When” slat board transmitter kit.  The circuit is from a 1940’s ARRL Article and used a 6V6 tube as a crystal oscillator on either 40 or 80 meters depending on the coils installed.  The chassis used orange crate wood.  Our retro kit uses Amish prepared oak and brass screws in the design.  If you are not familiar with our kit, go to and look at the home page as well as the ‘transmitter’ page.

The problem was crystals used in these transmitters can become damaged and ruined by excessive current. 

Crystal Current Limiter

Crystal Current Limiter

An old trick to prevent overheating and burnout of the crystals used in these transmitters is to put a 60 ma. bulb in series with the crystal.  We have experimented with this, and find it really works.  For this reason, Pastime Projects now offers this idea for crystal protection. We cannot guarantee it but its a lot cheaper than a new crystal!  It sells for $8.50 delivered to your US home..  Why not order a couple?  It come wired, (no socket) with pig tail wires for connection to your crystal.  See the web site to order.  Yes, there is instructions with each crystal protector.  Best regards  Glenn 



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