From: Mark Byrd

 About myself – 48, married w/ 2 kids and a dog.  I live in Spring (Houston), Texas and work for Shell.  My father had been in electronic communications all his life, and introduced me to my first crystal radio when I was about 5 (The REMCO crystal set).  At about 8 or 9, he gave me a Science Fair Globe Patrol kit.  While both radios are long gone, I have recently replaced them.  I’m still impressed with the Globe Patrol.  I built Heathkits all through high school, including three computers and a Hero robot.  My wife and I assembled cards for a company who supplied graphic cards for the Heath H8 computer, and used the money to buy her engagement ring.  I have piddled and invented with electronics all my life.  I also went through a spell of restoring dozens of antique radios from the 30’s and 40’s, and still have a dozen or so displayed around the house.  I have an electrical engineering degree from LSU.  I travel all around the world for work and like to hit the local electronics places when I have the chance.  Other hobbies:  My son and I race off-road motorcycles and I also enjoy streetbiking.  I’m also a woodworker – it is great to be able to tie my love for radios and woodworking together.


 
* The wood used for the base is Jatoba, which is similar to Mahogany in appearance, but denser.  I do the simple finish - 3 or 4 coast of rub-on gloss poly, followed by a couple of coats of satin spray poly. 



* For the crystal detector cup, I purchased a brass fitting from Harbor Freight (Item 47986) that converts an air hose down to an airbrush size hose.  I turned it by chucking it in my drill press, using a file and then progressively finer sandpaper.  To remove the threads on the inside, I used a cylindrical diamond carving bit for my Dremel tool.  I just held the bit it in my hand and worked the inside while spinning the brass fitting on my drill press. 



* For the detector stand post, I used 3/8" solid brass rod.  I made about 10 at once.  I started by boring the horizontal hole 3/4" from the end, then clamping the rod vertically in my drill press vice to bore a hole from the end to intersect the horizontal hole.  I threaded this hole with an 8-32 tap.  I cut this section off (total of 1") with a hacksaw and smoothed the ends on a disk sander.  Repeat for additional posts if desired.  Inside the stand is a small ball bearing and spring held in place by the bottom mounting screw.  This gives excellent stability/stiffness when adjusting the detector arm.  The detector arm is just a rod, threaded on both ends.  The cylindrical threaded brass nuts that hold the cat whisker are simply brass nuts turned round again on the drill press.





* I have purchased the 1/2" Delrin from a couple of suppliers.  It costs about $30/sq ft, and you can make two of these radios from one sq ft. 
* The Delrin cuts well on a table saw with a 40 to 50 tooth blade.  I used a scroll saw with a 12 tooth blade to cut the semi-circle.
* I used forstner bits to recess all screws in the panel, the crystal detector base and the wood base.  Most holes in the Delrin are tapped.
* The terminals are brushed nickel plated brass, readily available from my local electronics store (ACE electronics in Houston)



* The tuning capacitors are Pilot Capacigrads.  They were cleaned using Mike Starcher's method - first in an ultrasonic cleaner, then dipped in Klean-Strip Phosphoric Plus with one part clean water plus a tablespoon of Downey fabric softener.  Then coated with clear satin spray poly.
* The coil form is a 3" paper-based phenolic tube, purchased from a model rocket store, then painted with a mocha colored paint (not my favorite).  In my current project, I'm staining the same tube with mahogany stain, followed by a coat of satin spray poly. The windings are 25AWG silk-covered wire supplied by Kustomwire (frequently selling this wire on eBay). 
* Wiring is 0.064" square bus wire available from Antique Electronic Supply.
* The vernier dial is a 4" BMS dial.



I built a very simple coil winder, with a turns counter, for winding the coils.  The cones on the winder were made from a boat trailer bow guide, purchased at Academy Sports for $4. 


 
Thanks, Mark


 

Click Here to return to the Vintage Homebrew Projects Gallery page

© 2006-2008 ~ Michael R. Starcher ~ All Rights Reserved