[Boatanchors] Globe Scout 40A

[L L bahr]

While talking about Globe Scouts, be aware the 6V6 oscillator tube is VERY HARD on FT-243 crystals.  (More so on the thinner ones such as 40 meter and up crystals). The crystal current can easily fracture them.  After a few minutes of operation you will feel heat on the crystal case and a frequency counter will show drift as the crystal heats up.  Leo Myerson for years showed on his schematic the oscillator to be 6V6 or 6AG7.  Yet model after model he only used 6V6 tubes. If you rewire the tube socket for a 6AG7 tube using all the existing parts and then plugging in a 6AG7 tube, you will find there is much less strain on the crystal and you will also have more drive.  The 6AG7 is a wonderful oscillator compared to one using a 6V6. My friend WA5VGO came up with a great solution without modifying the radio.  He took an octal male plug with mounting brackets for chassis mounting and made an adapter out of it.  The male octal plug has two mounting wings on it so he bolted two spacers to the top of the octal male plug and then bolted a female octal tube socket to the tops of the two spacers.  (You wind up with an octal female tube socket straddled over or stacked above the octal male plug).  Then all you have to do is wire the bottom male plug for 6V6 wiring and the top socket for 6AG7 wiring.  Eureka!  You now can plug the adapter into the Globe Scout and then plug a 6AG7 tube into the adapter.  (All 6AG7 tubes were metal and almost all 6V6 tubes are metal, but not all.  Both metal tubes look alike.  I'm in the process of making one myself as the 6V6 is really heating up my crystal.  I'm going to make the change before I fracture my 7160 crystal I use everyday for QSOs with my AM buddies.  Now that WA5VGO has changed over to a 6AG7 tube, the crystal no longer feels warm after use.

As many of you know having built an Ameco AC-1 clone or using a real AC-1 clone which uses a 6V6 oscillator, it is tough on FT-243 crystals too.  You key up a AC-1 for extended periods using a 40 meter crystal and it will go POOF!  Forget any small Chinese crystal used in a 6V6 oscillator.  

One last note, you can use a color burst crystal down around 3.5 Mhz and double up to 40 meters.  The crystal gives plenty of drive and puts you on just slightly lower then 7158 KHz. (My color burst crystal is in a HC-6 holder). 

Lee, w0vt