[Heathkit] Re-Kitting my Basket Case DX-100

[L L bahr]

I finally took a bunch of pictures of my basket case DX-100 today.  That was what was holding me up from stripping the whole transmitter down to parts, then having the chassis parts re-plated and then build it up again as a new DX-100 kit. (The chassis is really rusty).  After taking the pictures, I then started to take the transmitter apart and I am maybe around a little over half done with that process.  I had a hard time removing a lot of the screws and nuts as many of them were rusted in place.  

Initially I was going to build up a new wiring harness out of Teflon wire, then I got lazy and decided to just clean up the old harness and now after taking much of the transmitter apart,  I am again convinced the right way to do this is make up a new wiring harness with colored Teflon stranded wire.  The old harness is made up of single strand wire and the insulation is getting hard.  I decided if I am going to build this transmitter up again as a new kit with new hardware, new capacitors, new resistors, and with a newly re-plated chassis, I need to use a nice new wiring harness.  (I plan to re-paint all the transformers too when installing them).  Somebody had replaced the 6146 tubes with 807 tubes and really messed up the tube wiring in this area as 807s need different tube sockets.  The area was a real rat's nest.  All the tubes were missing when I acquired the rig, but I now have replacement tubes for the rig.  My basket case transmitter was missing other parts too, but I now have purchased most of them from guys with parts rigs.

The screen resistors are undersized, so I plan to use larger wattage ones when re-installing them.  Also, the center tapped 30K 50 watt hi-voltage bleeder resistor will be replaced with two 15K resistors in series of the same wattage.  (I don't trust old bleeder resistors). Most likely I'll make some audio mods to the audio chain as once built up, the audio chain is almost impossible to work upon.

I rebuilt the meter lamp assembly as the wires from heat were brittle and exposed ready to short out.  I have rebuilt the 20/20/20 @450 can electrolytic by restuffing fresh new caps into the can.  (I used 22 mfd @ 450 volt radials rated at 105C).  For the two 125 mfd @450 volt hi-voltage caps I purchased some 250 mfd @ 450 volt  105C Snap In caps.  I made some 2 1/4 inch square printed circuit boards to accept the snap in caps and they have etched lands for the terminals and transmitter wires.  These boards will be bolted down to the cahssis using the same holes as used by the original can caps.  I purchased some 150 mfd @450 volt Nichicon caps rated for 105C. (These cost only around $3.00 each).  The bias caps are just a couple axial 22 mfd @ 160 volt caps.  The two high voltage caps are only around 7/8 inches in diameter and only approximately 1 inch tall  This is a far cry from the originals at around 1 1/4 iches in diameter and around 4 inches tall.  The new ones won't look original but they will look good on their PC boards.  (I could hide them by placing the old black carboard sleeves over them.

Since I am going to use mostly all new resistors, I have purchased modern 1 watt resistors to replace the old 1/2 watt ones and purchased 2 watt resistors for the 1 watt ones.  The new sizes mimic the size of the old resistors.  I'll most likely use LED #47 lamps for the meter and VFO dial to reduce heat on the nearbye plastic parts which have a tendency to warp.

When this rig is back together,  I plan to repaint the cabinet in original colors. 

That said, I built a DX-100 as a kid when they first came to production and it worked the first time it was turned on.  We will now see, 59 years later, if I can do it again!  This project is going to take some time and some effort.  I think it is going to look and work great when completed.

I love Heathkit DX-100s!

Lee, w0vt
Houston, Texas