EF86

<h2 id="characteristics">Characteristics</h2>
<p>6.3 <a href="/facts/Volt/KF18MXP2">Volt</a>, 200 mA indirectly heated A.F. miniature pentode with Noval (B9A) base with an EIA 9CQ (or 9BJ<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>) basing diagram.
</p>
<ul><li>Transconductance: 2.2 mA/V at Ia=3.0 mA, Ig2=0.6 mA, Va=250 V, Vg1=-2.2 V, Vg2=140 V, Vg3=0 V</li>
<li>Voltage gain: 185 (45<a href="/facts/Decibel/0LyxAPXh">dB</a>) at Vsupply=250 V, Ik=0.9 mA, Rk=2.2 kilohm, Ra=220 kilohm, Rg1=1 megohm, Vout<44 VRMS</li></ul>
<p>Special precautions have been taken in the design to reduce the:
</p>
<ul><li><a href="/facts/Mains_hum/c3w24hhy">Hum</a> (through a <a href="/facts/Bifilar/87qNc4UH">bifilar</a>-wound twisted pair of heater wires),</li>
<li><a href="/facts/Noise_(electronic)/Izbv38Rr">noise</a>, and</li>
<li>microphony (through a rigid internal structure to reduce resonances).</li></ul>
<p>The EF86 is much less noisy than other pentodes, but slightly noisier than some <a href="/facts/Triode/IGbT0RHa">triodes</a> at about 2 μV equivalent input noise to 10 kHz. Although used in circuits such as tape recorder input stages and instrument amplifiers, microphony can be a problem, even when mounted in a vibration-reducing valve holder.
</p>
<h2 id="equivalent-and-similar-devices">Equivalent and similar devices</h2>
<ul><li>6267 * Z729 * CV2901 * 6BK8 * 6CF8 * 6F22 * CV8068 * CV10098</li></ul>
<p>Special quality:
</p>
<ul><li>EF86SQ * M8195 * CV4085 * EF806S</li></ul>
<p>Different heater requirements:
</p>
<ul><li>PF86, 300 mA (4.5 V)</li>
<li>UF86, 100 mA (12.6 V)</li></ul>
<p>The rarely used EF83 is a remote-cutoff pentode<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> otherwise similar to the EF86; the remote cutoff (variable mu) makes it suitable for applications such as <a href="/facts/Automatic_gain_control/qY7qWtC7">automatic gain control</a> (AGC) in tape recorders.
</p>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://www.tubeworld.com/6267.htm">Tubeworld.com's EF86 page</a> <a href="https://web.archive.org/web/20061109155707/https://www.tubeworld.com/6267.htm">Archived</a> 9 November 2006 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a></li>
<li><a href="http://www.r-type.org/addtext/add036.htm">Mullard's EF86 at the National Valve Museum</a></li>
<li><a href="http://www.r-type.org/exhib/aai0113.htm">The Mullard EF36, EF37 and EF37A at the National Valve Museum</a></li>
<li><a href="http://tdsl.duncanamps.com/show.php?des=EF86">TDSL Tube data: EF86</a></li>
<li><a href="http://tdsl.duncanamps.com/sheets/ef86/ef86_01.pdf">Datasheet for Thorn/Mazda 6F22/EF86 (pdf)</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"www.thetubestore.com - EF86 Tubes". www.thetubestore.com. <a href="https://www.thetubestore.com/preamp-tubes/ef86-tube-types" target="_blank">https://www.thetubestore.com/preamp-tubes/ef86-tube-types</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"EF86 @ The Valve Museum". www.r-type.org. <a href="http://www.r-type.org/exhib/aai0113.htm" target="_blank">http://www.r-type.org/exhib/aai0113.htm</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"EF86 @ The Valve Museum". www.r-type.org. <a href="http://www.r-type.org/exhib/aai0113.htm" target="_blank">http://www.r-type.org/exhib/aai0113.htm</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>"Tube 4 EF86". Archived from the original on 27 September 2011. Retrieved 1 September 2010. <a href="https://web.archive.org/web/20110927175206/http://www.nj7p.org/Tube4.php?tube=EF86" target="_blank">https://web.archive.org/web/20110927175206/http://www.nj7p.org/Tube4.php?tube=EF86</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"EF83 @ The Valve Museum". www.r-type.org. <a href="http://www.r-type.org/exhib/aaa0527.htm" target="_blank">http://www.r-type.org/exhib/aaa0527.htm</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

EF86 open-in-new

EF86