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TRIODE.DOC
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1996-08-17
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T.A.P. Version 2.0 (C) 1989-1996
(Triode Amplifier Program)
FREEWARE
Courtesy of KD9JQ
T.A.P. Version 2.0 (Triode Amplifier Program) provides the Amateur with a new
Tool in Designing Triode Power Tube Amplifiers for Grounded Grid Service.
This Program should be considered as a designers aid only and does not represent
all facets of High Power Amplifier design. It is left to the user to verify
correct Filament Voltages and Currents for the frequency of operation, to verify
the correct plate voltage and dissipations per operating class, and as well as
the proper cooling and mounting methods recommended by the tube vendor. The user
does not need to have to Plate/Grid-Voltage/Current Plots to use this program
unless a new device data file is required.
The following information will guide the designer with Menus and Prompts.
Start:
1. Press <CR> to pull up the Library files of typical triodes.
2. Type in the file name (.TUB extension assumed) and press <CR>
3. A menu will pop up indicating 4 possible design selections or Exit.
F1 will find IBdc, RL Given PO, VDC, VBmin
F2 will find IBdc, PO Given RL, VBmin, VDC
F3 will find VBmax, PO Given IBdc, RL, VBmin, VDC
F4 will find VBmin, PO Given RL, IBdc, VDC
F9 Exit "Ends Program"
4. A series of prompts will appear requesting input from the designer.
Enter the requested information at this time. The program utilizes
Data from the Tube Library File to simulate the Tube Characteristics
at VBmin (Plate Voltage at full IB).
VDC = DC Plate Voltage @ no load.
Guideline;
Plate voltage should not exceed
VDC (Maximum rated) - (.5 * Vp-p Drive)
VBmax = Maximum Instantaneous Plate Voltage at IB @ cutoff.
Should not exceed VDC.
Page 2
VMmin = Minimum Instantaneous Plate Voltage at Peak Plate Current
** Hint ** Use 10% +/- 5% of VB to start.
Lower VMmin => higher Grid current, higher drive
Higher VMmin => lower Grid current, lower drive
Guideline;
VKmax < .75 * VBmin where VKmax = Peak Grid Voltage
VP = VBmax - VBmin (1/2 Plate Swing)
IBdc = DC Plate Current at Full Power
PO = Output Power Desired (Po to Load will reflect FeedThru Drive)
RL = Plate Load in Ohms (Final Load reflects FeedThru Drive)
FO = Operating Frequency (Mhz)
N = Number of Tubes used in Parallel (Not for Push Pull)
CLASS = C ( 165 Deg Conduction)
B ( 180 Deg Conduction)
AB1 ( 185 Deg Conduction
AB2 (~191 Deg Conduction)
USER (Conduction Angle or Bias)
USER Option:
You will be prompted for [A] Angle or [B] Bias.
The Angle allows the user to select a particular conduction
angle from 140 to 220 Degrees. The corresponding Bias voltage will be
calculated.
The Bias option allows you to enter a particular fixed voltage. The
corresponding Conduction Angle will be calculated. This option is
useful when using zero bias triodes. A bias of "0" volts must be
entered as a small number such as .0001.
5. A list of the calculated Design parameters will now be displayed.
Any exceeded values will flash red.
6. To obtain Input/Output Matching circuit data press either the up or
down arrow keys.
7. A display of matching circuits for input and outputs is now shown.
Input T or PI Matching circuit component values can be obtained by
Toggling the TAB key.
Page 3
VG = Peak Cath Voltage Swing
IB = Peak Plate Current IB(DC) = IB/Kb
IG = Peak Grid Current IG(DC) = IB/Kg
CA = Conduction Angle (Radians)
VK = Cathode Bias Voltage VK =(Cos(CA/2)*(VG+VBmin/U))+VDC/U)
Kb = PI^2/CA (Radians) Kg is a function of VK/(VG+VK)
Expected efficiency ~= (1 - (1/Kb)) * 100 %
PDCinput = VDC * IBdc Po = VP^2/(2*RL)
PDISS = PDC - Po
N (efficiency) = Po/PDC * 100 %
Po to Load = Po + Pfdthru where Pfdthru = (VG+VK)^2/(2*RB)
PGDISS = (VG+VK)^2/(2*RG) Grid Dissipation
RB = 2*(VG+VK)/IB RG = 2*(VG+VK)/IG
RK = 2*(VG+VK)/(IB+IG) Parallel Real component of Input Impedance
XP = -1 / (WO * CP)
CP = Cath-Grid Capacitance.
where WO = 2 * Pi * Fo
Converting to Series
RS = RP/((RK/XP)^2 + 1) XS = -RP*RS/XP
Zin = SQR(RS^2+XS^2) Magnitude of Zin
Phase Angle = 2*ATN(XS/(RS+Zin))
PIN = (VG+VK)^2/(2*Zin)
The Output is designed for a PI design with an additional C/L
circuit for intermediate impedance step up Transformation. If only
the PI circuit is desired, the user can input a new transformation
Impedance equal to the Load (50 ohms). The Plate Tuning Capacitance
has the RFC Plate Choke and Tube Capacitance reactance removed.
Items 1 thru 8 can be changed by the user at this time.
Select the Item number to change and enter the new value. Enter a
Negative number when entering Inductance, and a Positive number for
Capacitance. Only used for RFC's. <CR> to update screen to new
values.
Toggling the UP or Down Arrow Keys will alternately pop up the Data
Display or Matching Circuits.
8. The center Menu allows for "Dynamic" design of the matching
circuits. To use this option, you must have initially designed the
amplifier at the low end of the Band of interest and at the highest
expected output power with the F1 selection. Print out Data at
this time.
Press "D" and the program will prompt you for new power output level
(Lowest) and Upper Frequency end of the Band. The screen will now
display Matching circuit values required while maintaining constant
inductor values. Loaded Q and capacitance values are recalculated.
Print out the new Data at this time.
MENU will return you to the main menu.
FILE will return you to the .Tub Library.
PRINT will output the Data to your Printer.
QUIT will exit program.
Page 4
Note: The designer should account for drive and bias current
equalization of parallel devices. If there is adequate grid and
plate dissipation then the problem may not pose a problem at HF.
Circuit component losses are not figured in to the Gain. Use of
High Q components for low losses are required in high power
amplifiers.
Example:
A QL of 12 to QU of 400 => (1-(QL/QU))*100% efficiency or .22dB Loss
in the Tank Circuit. Subtract all Input & Output LC losses from
calculated Gain.
REFERENCES
RADIO HANDBOOK 22ND ED By William I. Orr Section 7
RCA TRANSMITTING TUBE TECHNICAL MANUAL TT-5 10-62 Pages 46 - 62
CARE & FEEDING OF POWER GRID TUBES VARIAN 4TH PRINTING 1982