Rick Campbell's One Transistor Amp Article

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W4AMV:
Hi Stu. I believe in you simulation that NPN Q1 and Q2 are the default "ideal" LT models. You need to right click on the device, pick a new device, and load in a real model. There are about 30 or so NPN devices in the model library, starting with the 2N2222, 3904 next, etc.... The 3866 may be in the latest version of LT, not sure. If not the Sandia Labs site has a reasonable model. Or, you can build your own model from measured data.

Alan

W4AMV:
Here is one model description for the 2N3866, not the one from Sandia Labs, but give it a try. The BF seems to large. It might be E2, not E3 !


******
* Spice Model
* Item: 2N3866
* Date: 8/11/10
* Revision History: A
* ==========================================================
* This model was developed by:
* Central Semiconductor Corp.
* 145 Adams Avenue
* Hauppauge, NY 11788
*
* These models are subject to change without notice.
* Users may not directly or indirectly re-sell or
* re-distribute this model. This model may not
* be modified, or altered without the consent of Central Semiconductor Corp.
*
* For more information on this model contact
* Central Semiconductor Corp. at:
* (631) 435-1110 or Engineering@centralsemi.com
* http://www.centralsemi.com
* ==========================================================
******
*SRC=2N3866;2N3866;BJTs NPN; Si;55.0V  0.40A  500MHz   Central Semi Central Semi
.MODEL 2N3866  NPN (
+ IS=13.232E-12
+ BF=1.2948E3
+ VAF=100
+ IKF=.13116
+ ISE=785.43E-12
+ NE=1.7362
+ BR=1.0408
+ VAR=100
+ IKR=3.3880
+ ISC=13.232E-12
+ NC=1.4860
+ NK=.72187
+ RB=8.9057
+ RC=1.7862
+ CJE=31.375E-12
+ VJE=.87558
+ MJE=.31831
+ CJC=7.3111E-12
+ VJC=.76419
+ MJC=.30725
+ TF=178.96E-12
+ XTF=10.044
+ VTF=10.275
+ ITF=5.8742
+ TR=10.000E-9 )
******

WA1GFZ:
you will need a supply of liquid gas to make a 2222 or 3904 run at that current. The 3866 is a beast and as I said a week ago you are asking way too much power from it. The guy who did that amplifier article is smoking dog poo.
I've been playing with the 3866 for almost 30 years.

AB2EZ:
Alan

I will try using that SPICE model a little latter this evening...

Frank

Off the top of your head, can you suggest a good choice of transistor for:

1 Watt output, class A (single ended), and <30 MHz applications?

Stu

W4AMV:
Hi Stu. Here is the Sandia Labs model. I would use this. Note, the BF is reasonable in this listing.  :)

Let us know how it works out. I agree with the comments on 1 watt levels from the 3866... however, if you optimize the drive level, bias point, and conduction angle, it may be possible to do quite well. I know Rick and he conducts a class on high eff. PA design... you can see his notes and lecture slides on the WEB.

.model 2N3866/27C  NPN     (
+         IS = 9.798605E-15
+         BF = 145.568899
+         NF = 1.007933
+        VAF = 64.3030691
+        IKF = 0.3661244
+        ISE = 1.806705E-14
+         NE = 1.6207001
+         BR = 10.471
+         NR = 1.0003673
+        VAR = 8.322
+        IKR = 0.1449443
+        ISC = 3.326752E-15
+         NC = 1.1076801
+         RB = 15.986
+        IRB = 2.530217E-3
+        RBM = 0.01
+         RE = 0.02604
+         RC = 1.0359
+        CJE = 9.055532E-12
+        VJE = 0.6761546
+        MJE = 0.2754969
+         TF = 1.25476E-10
+        XTF = 13.0616413
+        VTF = 0.4699
+        ITF = 0.2828
+        PTF = 18.9645325
+        CJC = 7.054363E-12
+        VJC = 0.5769848
+        MJC = 0.3139067
+       XCJC = 1
+         TR = 9.098362E-8
+        CJS = 0
+        VJS = .75
+        MJS = 0
+        XTB = 1.831
+         EG = 1.11
+        XTI = 5.0205
+         KF = 0
+         AF = 1
+         FC = 0.9
+ )

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