{"id":5599,"date":"2016-05-29T12:44:52","date_gmt":"2016-05-29T11:44:52","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=5599"},"modified":"2016-05-29T12:44:52","modified_gmt":"2016-05-29T11:44:52","slug":"rl12p35-german-transmitting-pentodes","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2016\/05\/29\/rl12p35-german-transmitting-pentodes\/","title":{"rendered":"RL12P35 German Transmitting Pentodes"},"content":{"rendered":"

It was pure lust and love at first sight. I found the RL12P35 german transmitting pentodes <\/a>and couldn’t resist in buying them. A very nice set of NOS Telefunken and Valvo valves with also NOS sockets. These pentodes look like a de-rated LS-50\/GU-50 and very interesting candidates for a nice PP amp:<\/p>\n

\"RL12P35 <\/a>
RL12P35 valves <\/div> <\/div> <\/div>
\"Note <\/a>
Note the Nazi printing! <\/div> <\/div> <\/div> <\/div> <\/div>\n

These have been used by Lorenz to build the classic and lovely PP amp LVA\/BA30 RL12P35 Amp<\/a> with anode to grid feedback (i.e. a la Schade) like the below amplifier:<\/p>\n

<\/p>\n

When I submitted to the mercy of the uTracer, I had to work around the 300V limitation of my uTracer v3 (I do have the 400V upgrade kit but I haven’t got around to modify it yet). So I looked into the data sheet to find an operating point to measure my valves against:<\/p>\n

\"RL12P35<\/a>
RL12P35 test point<\/figcaption><\/figure>\n

The valves measured really well, most of them above 90%. The test point used was Va=250V, Vs=200V, Vgk=-15V which aimed for Ia=110mA:<\/p>\n

\"RL12P35<\/a>
RL12P35 (valve 9) used for creating the Spice Model<\/figcaption><\/figure>\n

From my traces I could see that the screen current should be about 25mA, Ra closer to 24-25k\u03a9 and transconductance around 4.5mA\/V which is predicted from the data sheets.<\/p>\n

The generated Spice model matches really well:<\/p>\n

\"RL12P35<\/a>
RL12P35 @Vs=250V<\/figcaption><\/figure>\n
\"RL12P35<\/a>
RL12P35 @Vs=200V<\/figcaption><\/figure>\n
\"RL12P35<\/a>
RL12P35 Screen Current @Vs=200V<\/figcaption><\/figure>\n
\"RL12P35<\/a>
RL12P35 triode curves<\/figcaption><\/figure>\n

 <\/p>\n

Here is the Spice model of the pentode:\u00a0RL12P35-pentode-150V<\/a>:<\/p>\n

****************************************************\n.SUBCKT RL12P35-pentode 1 2 3 4 ; A G2 G1 C;\n* Extract V3.000\n* Model created: 28-May-2016\n*\n* Traced and model created by Ale Moglia \/ valves@bartola.co.uk\n* www.bartola.co.uk\/valves\n*\n*\n*\nX1 1 2 3 4 BTetrodeDE MU= 5.01 EX=1.331 kG1= 676.1 KP= 14.9 kVB = 1008.8 kG2= 3519.4\n+Sc=.12E+00 ap= .034 w= 16. nu= .24 lam= 11.8\n+ Ookg1mOokG2=.119E-02 Aokg1=.46E-06 alkg1palskg2=.119E-02 be= .151 als= 3.10 RGI=2000\n+ CCG1=16.5P CCG2 = 0.0p CPG1 = 0.05p CG1G2 = 5.7p CCP=10.4P ;\n.ENDS\n\n****************************************************\n.SUBCKT BTetrodeDE 1 2 3 4; A G2 G1 C\n*\n* NOTE: LOG(x) is base e LOG or natural logarithm.\n* For some Spice versions, e.g. MicroCap, this has to be changed to LN(x).\n*\nRE1 7 0 1MEG ; DUMMY SO NODE 7 HAS 2 CONNECTIONS\nE1 7 0 VALUE=\n+{V(2,4)\/KP*LOG(1+EXP(KP*(1\/MU+V(3,4)\/SQRT(KVB+V(2,4)*V(2,4)))))}\nE2 8 0 VALUE = {Ookg1mOokG2 + Aokg1*V(1,4) - alkg1palskg2*Exp(-be*V(1,4)*SQRT(be*V(1,4)))}\nE3 9 0 VALUE = {Sc\/kG2*V(1,4)*(1+tanh(-ap*(V(1,4)-V(2,4)\/lam+w+nu*V(3,4))))}\nG1 1 4 VALUE = {0.5*(PWR(V(7),EX)+PWRS(V(7),EX))*(V(8)-V(9))}\nG2 2 4 VALUE = {0.5*(PWR(V(7),EX)+PWRS(V(7),EX))\/KG2 *(1+als*Exp(-be*V(1,4) * SQRT(be*V(1,4))))}\nRCP 1 4 1G ; FOR CONVERGENCE A - C\nC1 3 4 {CCG1} ; CATHODE-GRID 1 C - G1\nC4 2 4 {CCG2} ; CATHODE-GRID 2 C - G2\nC5 2 3 {CG1G2} ; GRID 1 -GRID 2 G1 - G2\nC2 1 3 {CPG1} ; GRID 1-PLATE G1 - A\nC3 1 4 {CCP} ; CATHODE-PLATE A - C\nR1 3 5 {RGI} ; FOR GRID CURRENT G1 - 5\nD3 5 4 DX ; FOR GRID CURRENT 5 - C\n.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)\n.ENDS BTetrodeDE<\/pre>\n
Enjoy!<\/p>\n
Ale<\/p>\n","protected":false},"excerpt":{"rendered":"
It was pure lust and love at first sight. I found the RL12P35 german transmitting pentodes and couldn’t resist in buying them. A very nice set of NOS Telefunken and Valvo valves with also NOS sockets. These pentodes look like a de-rated LS-50\/GU-50 and very interesting candidates for a nice PP amp: These have been … Continue reading “RL12P35 German Transmitting Pentodes”<\/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_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":[5],"tags":[192,912,913,916,917,915,914],"class_list":["post-5599","post","type-post","status-publish","format-standard","hentry","category-valves","tag-gu50","tag-ls50","tag-rl12p35","tag-rl12p35-pentode","tag-rl12p35-spice-model","tag-rl12p35-triode","tag-telefunken"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-1sj","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5599","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=5599"}],"version-history":[{"count":2,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5599\/revisions"}],"predecessor-version":[{"id":5610,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5599\/revisions\/5610"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=5599"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=5599"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=5599"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}