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POWER AMPLIFIERS. PRO and CON By Dave Russell, W2DMR Forest Cummings, W5LQU. Basic power amplifier. RF Drive. PA. AC?. ALC. Cooling. AC Power. PS. POWER AMPLIFIER TYPES. Vacuum Tube High impedance – high voltage – danger! Tuned network – PI – 3:1 VSWR – No Coupler - PowerPoint PPT Presentation
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PRO and CON
By Dave Russell, W2DMR
Forest Cummings, W5LQU
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PA
PS
AC?RF Drive
ALC
AC Power
Cooling
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Vacuum Tube High impedance – high voltage – danger! Tuned network – PI – 3:1 VSWR – No Coupler Two versions – Grid Driven /low drive Grounded Grid/high drive
Solid State Low impedance – high current Fixed tuning – 50 ohms – max VSWR 2:1 Two versions – Bipolar Junction Transistors Field Effect Transistors
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Rated Power Output – EfficiencyClass C – Class AB1Max allowable VSWRModes – SSB – CW – Digital – RTTYPlate Voltage – Collector VoltageStatic CurrentMax Full Load Plate/Collector currentTuning Required – Network/Antenna CouplerDrive required Cooling required – BlowerALC providedInput AC power – 120v/240v
TRIODES 811 A 25.00 572 B 50.00 3-500 Z 189.00 3 CX 800 A7 850.00 3-1000 Z 850.00 3 CX 1200 A7 ? 3 CX 1500 A7 950.00
TETRODES 4 X 150 ? 4 CX 250 B 185.00 4 CX 350 B 190.04 4 CX 400B 350.00 4 CX 1000 A 600.00 4 CX 1500 B 1275.00 4 CX 1600 B ?
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Power Out – Splatter - Distortion
RF drive – splatter – grid damage - distortionALC – too much – pumping - distortionNeutralizing – instability – parasitesLow line voltageCooling – RTTY – voice/CWFilament Voltage – tube life – low emission - low outputIncorrect Loading – distortionIncorrect Static current (bias) - distortion
Watts S units dB
1500w S 9 +12800 w S 8.5 +9400w S 8 +6100w S 7 0dB ref25w S 6 -65w S5
-131w S4
-20
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11100 WATT TRANSCEIVER 300WCPLR
DIPOLE ANTENNA
0dB Reference
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11100 WATT TRANSCEIVER 1500W CPLR
DIPOLE ANTENNA
+12dB (2 S units)
1500 WPOWER AMP
240 VAC
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AL-811H4-811A Tubes800 w output120 vac$799Tube cost $90
AL-80B3-500Z Tube1000w output120/240 vac$1329Tube cost $189
AL-15003CX1500A7 (8827)1500w output240 vac$3349Tube cost $1275
Antenna CouplerMFJ 989D1500w50 ohm Dummy LoadSWR Meter4:1 Balun6 position switch$390
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Cushcraft 3 element tribander (20-15-10m) 8dBi/25dB fb $549
Hygain 3 element tribander (20-15-10m) 8dBi/25 dB fb $419
40 foot tower $669
50 foot tower $939
Rotator HAM – IV $589
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Total cost = $1677 to $2077
100w3 element beam40 foot towerHAM-IV Rotator6dB increase in ERP6dB increase in received signal10/20 dB less QRMCost = $1707
800 wattsAL-811 PAMFJ 989D Ant Cplr40 foot tower3 element beamHAM-IV Rotator15 dB increase in ERP6dB in receive10/20 dB less QRMCost = $2896
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AL-1500 Power AmplifierMFJ989D Antenna Coupler3 Element Triband Beam40 foot towerHAM-IV Rotator240 vac service18dB increase in ERP6dB increase in Receive10/20 dB less QRMCost = $5646
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•Power Amplifiers can give maximum ERP•PA s really help on DX pileups and contests•PA s don’t help the received signal or QRM•Power Amplifiers are very expensive•Power Amplifiers are dangerous (high voltage)•Over about 800 watts you need 240 vac line•HI Power Antenna Couplers and Dummy Loads are requiredAntennas help both TX and RX signals
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SPEND YOUR MONEY ON YOUR ANTENNA FIRST,
THEN GO ON TO A POWER AMPLIFIER !