ÿþ<html> <head> <meta http-equiv=Content-Type content="text/html; charset=unicode"> <meta name=Generator content="Microsoft Word 12 (filtered)"> <title>Air-Cooled Kenotrons</title> <style> <!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4;} @font-face {font-family:Tahoma; panose-1:2 11 6 4 3 5 4 4 2 4;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0in; margin-bottom:.0001pt; font-size:12.0pt; font-family:"Times New Roman","serif";} a:link, span.MsoHyperlink {color:blue; text-decoration:underline;} a:visited, span.MsoHyperlinkFollowed {color:purple; text-decoration:underline;} p {margin-right:0in; margin-left:0in; font-size:12.0pt; font-family:"Times New Roman","serif";} p.MsoAcetate, li.MsoAcetate, div.MsoAcetate {mso-style-link:"Balloon Text Char"; margin:0in; margin-bottom:.0001pt; font-size:8.0pt; font-family:"Tahoma","sans-serif";} span.BalloonTextChar {mso-style-name:"Balloon Text Char"; mso-style-link:"Balloon Text"; font-family:"Tahoma","sans-serif";} p.msochpdefault, li.msochpdefault, div.msochpdefault {mso-style-name:msochpdefault; margin-right:0in; margin-left:0in; font-size:10.0pt; font-family:"Times New Roman","serif";} .MsoChpDefault {font-size:10.0pt;} @page WordSection1 {size:595.3pt 841.9pt; margin:9.0pt 1.25in 0in 1.25in;} div.WordSection1 {page:WordSection1;} --> </style> </head> <body bgcolor="#FFFFCC" lang=EN-US link=blue vlink=purple> <div class=WordSection1> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:7.5pt'>&nbsp;</span></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:20.0pt'>&nbsp;Cold Cathode Valves and Air-Cooled Kenotrons</span></p> <div align=center> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=568 valign=top style='width:426.1pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=right style='text-align:right'><i><span style='font-size:14.0pt;color:maroon'>Click on an item for details</span></i></p> </td> </tr> </table> </div> <p class=MsoNormal><span style='font-size:7.5pt'>&nbsp;</span></p> <div align=center> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=717 style='width:537.55pt;margin-left:28.9pt;border-collapse:collapse'> <tr> <td width=354 colspan=2 valign=top style='width:265.55pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><u><span style='font-size:16.0pt'>Cold Cathode Valves</span></u></p> <p class=MsoNormal><u><span style='font-size:7.5pt;color:white'>&nbsp;</span></u></p> </td> <td width=181 colspan=2 valign=top style='width:135.5pt;padding:0in 0in 0in 0in'> <p class=MsoNormal>&nbsp;</p> </td> <td width=182 valign=top style='width:136.5pt;padding:0in 5.4pt 0in 5.4pt'></td> </tr> <tr> <td width=179 valign=top style='width:134.15pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/gundelach-rectifier-valve.html"><span style='font-size:22.0pt;text-decoration:none'><img border=0 width=146 height=109 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image012.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/gundelach-rectifier-valve.html">Gundelach Valve</a></span></p> </td> <td width=176 colspan=2 valign=top style='width:131.9pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/lodge-rectifier-valve.html"><span style='font-size:22.0pt;text-decoration:none'><img border=0 width=144 height=111 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image002.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/lodge-rectifier-valve.html">Lodge Valve</a></span></p> </td> <td width=180 valign=top style='width:135.0pt;padding:0in 0in 0in 0in'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/victor-cold-cathode-valve.htm"><span style='font-size:11.0pt;color:windowtext;text-decoration:none'><img border=0 width=144 height=110 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image003.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/victor-cold-cathode-valve.htm">Victor Valve</a></span></p> </td> <td width=182 valign=top style='width:136.5pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/andrews-twin-rectifier-valve.html"><span style='font-size:11.0pt;color:windowtext;text-decoration:none'><img border=0 width=135 height=110 id="Picture 15" src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image001.jpg" alt=image003></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/andrews-twin-rectifier-valve.html">Andrews Twin Valve</a></span></p> </td> </tr> <tr> <td width=179 style='width:134.15pt;padding:0in 0in 0in 0in'></td> <td width=176 colspan=2 style='width:131.9pt;padding:0in 0in 0in 0in'></td> <td width=180 style='width:135.0pt;padding:0in 0in 0in 0in'></td> <td width=182 style='width:136.5pt;padding:0in 0in 0in 0in'></td> </tr> <tr> <td width=179 style='width:134.25pt;padding:0in 0in 0in 0in'></td> <td width=175 style='width:131.25pt;padding:0in 0in 0in 0in'></td> <td width=1 style='width:.75pt;padding:0in 0in 0in 0in'></td> <td width=180 style='width:135.0pt;padding:0in 0in 0in 0in'></td> <td width=182 style='width:136.5pt;padding:0in 0in 0in 0in'></td> </tr> </table> </div> <p class=MsoNormal><span style='font-size:7.5pt'>&nbsp;</span></p> <p class=MsoNormal>&nbsp;</p> <div align=center> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=731 style='width:548.4pt;margin-left:24.85pt;border-collapse:collapse'> <tr> <td width=220 valign=top style='width:165.3pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal>&nbsp;</p> <p class=MsoNormal><u><span style='font-size:16.0pt'>Air-Cooled Kenotrons</span></u></p> <p class=MsoNormal><span style='font-size:7.5pt'>&nbsp;</span></p> </td> <td width=306 colspan=2 valign=top style='width:229.8pt;padding:0in 5.4pt 0in 5.4pt'></td> <td width=204 valign=top style='width:153.3pt;padding:0in 5.4pt 0in 5.4pt'></td> </tr> <tr> <td width=220 valign=top style='width:165.3pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/general-electric-kr-3-&amp;-kr-4-kenotrons.html"><span style='text-decoration:none'><img border=0 width=197 height=70 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image004.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/general-electric-kr-3-&amp;-kr-4-kenotrons.html">General Electric&nbsp; KR-3</a></span></p> </td> <td width=306 colspan=2 valign=top style='width:229.8pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/huge-machlett-kenotron.html"><span style='text-decoration:none'><img border=0 width=190 height=73 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image005.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/huge-machlett-kenotron.html"><span style='font-size:11.0pt'>Machlett ML8094/199 </span><span style='font-size: 10.0pt'>and Machlett-Raytheon ML5578/200</span></a></p> <p class=MsoNormal align=center style='text-align:center'>&nbsp;</p> </td> <td width=204 valign=top style='width:153.3pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/valvix-kenotron.html"><span style='font-size: 10.0pt;text-decoration:none'><img border=0 width=179 height=66 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image006.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/valvix-kenotron.html">Tubix (France)</a></span></p> <p class=MsoNormal align=center style='text-align:center'>&nbsp;</p> </td> </tr> <tr> <td width=220 valign=top style='width:165.3pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/philips-type-k-kenotron.html"><span style='text-decoration:none'><img border=0 width=204 height=62 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image007.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/philips-type-k-kenotron.html">Philips Type K</a></span></p> <p class=MsoNormal align=center style='text-align:center'>&nbsp;</p> </td> <td width=306 colspan=2 valign=top style='width:229.8pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/philips-metalix-kenotron.html"><span style='font-size:10.0pt;text-decoration:none'><img border=0 width=198 height=66 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image008.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/philips-metalix-kenotron.html">Philips Metalix, England</a></span></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:7.5pt'><br> &nbsp;</span></p> </td> <td width=204 valign=top style='width:153.3pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/early-philips-large-size-kenotron.html"><span style='text-decoration:none'><img border=0 width=188 height=69 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image009.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/early-philips-large-size-kenotron.html">Philips (England)</a></span></p> </td> </tr> <tr> <td width=220 valign=top style='width:165.3pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:7.5pt'>&nbsp;</span></p> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/machlett-ml-26-kenotron.html"><span style='font-size:11.0pt;text-decoration:none'><img border=0 width=200 height=47 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image010.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/machlett-ml-26-kenotron.html">Machlett ML-26</a></span></p> <p class=MsoNormal align=center style='text-align:center'>&nbsp;</p> </td> <td width=306 colspan=2 valign=top style='width:229.8pt;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal align=center style='text-align:center'><a href="../AIRCOOLEDKENOTRONS8/early-air-cooled-kenotron.html"><span style='font-size:10.0pt;text-decoration:none'><img border=0 width=184 height=59 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image011.jpg"></span></a></p> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt'><a href="../AIRCOOLEDKENOTRONS8/early-air-cooled-kenotron.html">Unknown make</a></span></p> <p class=MsoNormal align=center style='text-align:center'>&nbsp;</p> </td> <td width=204 valign=top style='width:153.3pt;padding:0in 5.4pt 0in 5.4pt'></td> </tr> <tr> <td width=220 style='width:165.3pt;padding:0in 0in 0in 0in'></td> <td width=160 style='width:120.3pt;padding:0in 0in 0in 0in'></td> <td width=146 style='width:109.5pt;padding:0in 0in 0in 0in'></td> <td width=204 style='width:153.3pt;padding:0in 0in 0in 0in'></td> </tr> <tr> <td width=220 style='width:165.0pt;padding:0in 0in 0in 0in'></td> <td width=160 style='width:120.0pt;padding:0in 0in 0in 0in'></td> <td width=146 style='width:109.5pt;padding:0in 0in 0in 0in'></td> <td width=204 style='width:153.0pt;padding:0in 0in 0in 0in'></td> </tr> </table> </div> <p class=MsoNormal align=center style='text-align:center'><span style='font-size:7.5pt'>&nbsp;</span></p> <div align=center> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=664 style='width:498.1pt;margin-left:32.7pt;border-collapse:collapse'> <tr style='height:225.9pt'> <td width=664 valign=top style='width:498.1pt;padding:0in 5.4pt 0in 5.4pt; height:225.9pt'> <p class=MsoNormal>&nbsp;</p> <p class=MsoNormal>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;<span style='font-size:11.0pt'>Kenotrons are vacuum rectifying hot-cathode valves of the diode type, used until the Seventies in the high tension circuits of x-ray tubes. The first Kenotron was introduced by Saul Dushman in 1914 (the K3 of General Electric, put on the market a few years later).&nbsp;</span><span style='font-size:7.5pt'> </span></p> <p class=MsoNormal><span style='font-size:7.5pt'>&nbsp;</span></p> <p class=MsoNormal><span style='font-size:11.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Early kenotrons were of a remarkably large size in order to ascertain adequate cooling in the ambient air. Later makes were fitted, like x-ray tubes, with some sort of metal heat radiator fixed to the anode end of the tube. But finally, like x-ray tubes, kenotrons became smaller in their external size and were oil-immersed in the high-tension transformer tank of the x-ray unit.<br> </span><span style='font-size:7.5pt'>&nbsp;</span></p> <p class=MsoNormal><span style='font-size:11.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; In the late sixties and during the seventies solid state <span style='color:blue'><a href="../RADIOLOGYRELATEDITEMS8/solid-state-rectifier.html">semiconductor rectifiers</a></span> replaced kenotrons in high tension generators. Most modern x-ray units are presently equipped with electronically controlled high frequency generators.</span></p> <p class=MsoNormal><span style='font-size:7.5pt'>&nbsp;</span></p> <p class=MsoNormal><span style='font-size:11.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Prior to the invention of the kenotron in 1914, rectifier valves were of the cold-cathode (filament-less) type. Three of them are presented in this series.<br> </span>&nbsp;</p> <div align=center> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=606 valign=top style='width:454.65pt;border:solid windowtext 1.0pt; padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal style='text-align:justify'><b><i><u><span style='font-size:11.0pt;color:maroon'>A Prophecy</span></u></i></b><span style='font-size:11.0pt;color:maroon'> :&nbsp; In his book  Textbook of Radiolgy , 1918, p.62 , in the chapter about valves, Edward Reginald Morton wrote:  <b>& . </b></span><b><span style='font-size:10.0pt;color:maroon'>It will, of course, be understood that if we had a purely unidirectional supply of current for our tube, no rectifying device would be necessary& & ..Such a supply is not only possible but more or less easily available, and in all probability valve tubes and such devices will be relegated to the museum of X-ray antiquities .</span></b></p> </td> </tr> </table> </div> </td> </tr> </table> </div> <p class=MsoNormal style='text-align:justify'><br> &nbsp;</p> <div align=center> <table class=MsoNormalTable border=0 cellpadding=0 id=table1> <tr> <td width=326 style='width:244.5pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal align=right style='text-align:right'><a href="oil-immersed-hot-cathode-fixed-anode-and-special-purpose-8.html">Previous</a></p> </td> <td width=321 style='width:240.75pt;padding:.75pt .75pt .75pt .75pt'> <p align=center style='text-align:center'><span style='font-size:10.0pt'>&nbsp;</span></p> </td> <td width=328 style='width:246.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal><a href="oil-immersed-kenotrons-index-8.html">Next</a></p> </td> </tr> <tr> <td width=326 valign=top style='width:244.5pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal align=right style='text-align:right'><img border=0 width=57 height=25 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image001.gif"></p> </td> <td width=321 style='width:240.75pt;padding:.75pt .75pt .75pt .75pt'> <p align=center style='text-align:center'><a href="../index.html">Go to Main Page</a></p> </td> <td width=328 style='width:246.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal><img border=0 width=57 height=25 src="cold-cathode-valves-andair-cooled-kenotrons-index-8_files/image002.gif"></p> </td> </tr> </table> </div> <p class=MsoNormal>&nbsp;</p> </div> </body> </html>