{"id":1065,"date":"2013-01-13T16:15:09","date_gmt":"2013-01-13T16:15:09","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=1065"},"modified":"2013-01-13T16:16:22","modified_gmt":"2013-01-13T16:16:22","slug":"4p1l-pentode-driver-continued","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2013\/01\/13\/4p1l-pentode-driver-continued\/","title":{"rendered":"4P1L pentode driver (continued)"},"content":{"rendered":"

\"4P1L<\/a>After the initial tests done with the 4P1L in pentode mode and filament bias, I thought a bit about how this driver could be implemented in practice. I may try this configuration in my 4-65a SE amp, but am not urged by this at all.<\/p>\n

The screen supply is formed by a gas valve (SG3S) which provides a very stable reference when feed by a CCS. In this case the cascoded pair M3 and M4 will provide in conjunction with R4 and U2 a very low noise screen current to U1. \u00a0R9 has to be adjusted on test to set a current of about 15mA on the CCS. The 4P1L will draw 1.8mA at 81V as screen current, so R4 may also need adjustment to set the right operating point.<\/p>\n

The driver should provide about a gain of 150. Driving easily a transmiting vale (or why not a 300B \ud83d\ude42 ) in class A2 with this configuration. My tests showed a maximum THD of about 0.27% at 200Vpp.<\/p>\n

Gain could be reduced if needed by tweaking the RL. And if stacked supplies are not used, then a single +400V supply could be used with additional dissipation across the reference currents (M1 and M3\/M4).<\/p>\n

Keep thinking…<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

After the initial tests done with the 4P1L in pentode mode and filament bias, I thought a bit about how this driver could be implemented in practice. I may try this configuration in my 4-65a SE amp, but am not urged by this at all. The screen supply is formed by a gas valve (SG3S) … Continue reading “4P1L pentode driver (continued)”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[150,153,158,67,5],"tags":[137,782,286,285],"class_list":["post-1065","post","type-post","status-publish","format-standard","hentry","category-4-65a-se-amplifier-2","category-driver","category-se-designs","category-thd","category-valves","tag-4-65a-se-amplifier","tag-4p1l","tag-4p1l-driver","tag-4p1l-pentode"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-hb","jetpack_likes_enabled":true,"jetpack-related-posts":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/1065","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/comments?post=1065"}],"version-history":[{"count":2,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/1065\/revisions"}],"predecessor-version":[{"id":1068,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/1065\/revisions\/1068"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=1065"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=1065"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=1065"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}