[Heathkit] DX-100 Spot Switch (Little Red Push Button)

[Glen Zook]

The mod was to the DX-100 and the DX-100B.  This modification was included in the MK-1 kit which also "improved" the keying of those transmitters.  However, adding the spotting switch is independent of the keying modification and can be done without changing the keying.  The only thing is that the simple DPST push button switch is no longer available, at least I have not been able to find one of the original type anywhere.  But, you can use a more expensive momentary contact DPDT and that works very well.

The TX-1 Apache came with the spotting switch.

A copy of the official Heath paperwork for adding the spotting switch and improved keying are part of the information available at

http://k9sth.com/uploads/Heathkit_DX-100_mods-1.pdf


Please note that this document is fairly large and may take a while to download if you do not have a high speed Internet connection.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
From: L L bahr <pulsarxp at embarqmail.com>
To: heathkit at mailman.qth.net
Sent: Sunday, October 30, 2011 7:14 PM
Subject: [Heathkit] DX-100 Spot Switch (Little Red Push Button)


As a kid,  I built a DX-100, not a B and an Apache TX-1.  I remember adding a little red push botton switch on one of them as a "spot" switch.  I can't remember if I did it on the DX-100 or the TX-1.  I think it was a Heathkit endorsed modification. Does anyone remember on which transmitter this was added as a useful mod? I really enjoyed my DX-100 and TX-1 transmitter.  As years went on,  I moved over to SSB but never purchased a Heathkit SSB rig.  Not even to this day.  I plan to get a DX-100 station up and running again.  The thought of running one again really has me excited.  

As mentioned earlier,  I plan to restore from the "ground up", a basket case DX-100 plus one other, if I can ever find one, but it will be just a restoration and not a ground up project.  I'm not sure I will solid state the power supplies as I know SS will ease the filament load on the transformers yet boost the output power.  If one moves the capacitor from the transformer side of the 5V4 tube to the load side of the filter choke, the increase can be cancelled.  There is good and bad to going with SS rectifiers or with valve rectifiers.  Right now I am trying to figure out how to take some really great shots of the "before" restoration of the basket case DX-100.

Lee, w0vt 
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