Active Antenna Amplifier Notes

Active antennas are any antennas with integrated signal amplifiers built right into the unit. While, passive antennas are antennas that have no amplification stages.

An active antenna is a passive antenna that simply includes an onboard amplifier. There is no difference between the antenna element of an active or passive antenna of the same type; the only difference is whether an amplifier is included.

Active antennas can be used for both receiving and transmitting applications, but they are most often seen as receiving antennas. When used to receive signal, the integrated amp boosts the RF picked up by the antenna and allows much longer remote cable runs.

The post Active Antenna Amplifier For FM Radio appeared first on Amplifier Circuit Design.

The heart of this stage is an RF transistor (the BLY90) which, together with the classical passive components in such systems, performs the function of amplifying the radio signal present at its base to deliver to its collector.

The power supply is 14V, with a current of 7 to 8A. It is almost impossible at this stage parasitic oscillations occur. Second harmonic suppression is better than 45dB.

L1 3 Turns on air 7mm
L2 Shock of RF 0.22μH
L3 15 turns 0.5mm wire on a 47K resistor ½ W
L4 3 Turns on air 5mm
L5 Arch 25mm high by 15mm wide. 0.5mm to 5mm wire
L6 Shock RF
L7 3 Turns on air 7mm
L8 4 Turns on 8mm air

The post 70W FM amplifier appeared first on Amplifier Circuit Design.

1500 watt RF Amplifier parts list :

C1,2-0.01 µF silver mica transmitting capacitor
C3-1500 pF screen grid bypass (internal to tube socket)
C4-2000 pF, S kV, two 858S capacitors in parallel, Centralab
C5-Vacuum variable, 10 to 300 pF, 10 kV, Jennings UCS-300 (plate tuning)
C6-300 pF, 5 kV, Centralab-type 858S
C7-Vacuum variable, 3000 pF maximum,
3 kV, Jennings UCSL-3000 (loading) C8-0.0014µF, 10 kV (EM)
C9-0.005µF, 15 kV oil capacitor
C10,11-500 pF. 20 kV “TV doorknob,” Centralab
CI 2-0.05 µF, 20 A feedthrough, Sprague C13,14,15-1000 pF feedthrough
C16-0.1 IF, 100 volts DC disc ceramic D1-Silicon diode, 1 N4148 or 1 N914 F1-3Afuse
J1-BNC chassis mount
J2-N chassis mount
J3-HN chassis mount, used with RG213 for 3 kV feed
J4-Chassis-mount AC outlet, Amphenol 160-2N, AL part no. 713-5202
Lamp-No. 47 6.3 volt lamp
L1-3.5 turns no. 10 silver-plated wire, 1 inch ID, 2 inches long, self-supporting
L2-24 H roller inductor, Johnson 226-1 (EM, CC)
M1-1 mA DC meter movement, filament voltage
R1-50 ohm, 60 watt noninductive resistor,thirty 1500 ohm 2 watt carbon composition resistors connected in parallel
R2-1000 ohm, 2 watt carbon composition
R3-100 ohm, 2 watt carbon composition
R4-220 K, 2 watt carbon composition
R5-25 ohm, 25 watt wirewound adjustable
R6-1000 ohm, 2 watt carbon or wirewound potensiometer
R7-10,000 ohm, 2 watt carbon composition
RFC1-28 turns no. 18 wire solenoid wound
on 0.5 inch OD by 2.5 inch ceramic form (plate choke)
RFC2-Plate choke, surplus part (suggest B&W 801)
RFC3-74 turns no, 20 wire solenoid wound on 0.75 OD by 3 inch ceramic form
RFC4-9 µH 15 A RF choke, surplus part(suggest Dale no. IH15, HF no. 18-105)
RFC5-1.0 mH RF choke
RFC6-10 H, 1 A RF choke
RT1-Surgistor, GC 25-933-S
S1-Air flow switch, Rotron 2A-1 350
SK1-Eimac socket, Sk810B; chimney SK-806 (BY)
T1-Transformer, 6.3 volts AC at 10 A secondary, Thordarson 21 F12, AL 704-2019
Z1-Zener diode, 6.2 volts, 1 N473

The frequency range of this amplifier is 1.8 to 54 MHz. The amount of RF drive needed for full output is around 30 W. grid compartment (R1, R2, RFC4, RFC5) must be protected from the other circuitry-especially the output circuitry.

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The two-stage, 4W, SD1598/SD1853 amplifier.
C4, C12 to C14    0.3 to 3pF Johanson piston trimmer.
D1    1N4747A 20-V, 1 W Zener.
Q1    SD1598.
Q2, Q3    SD1853.
R2    1.5 to 1.7 kohm, 1/2W.
R3    1 to 2ohm,2W,
RFC1 to RFC4 : 8 turns of #28 enam. wire, cloaewound, 0.1″  ID.

Parts-placement diagram for the 2 x S01853 amplifier. The PC-board edges are not shown. All components mount to the trace side of the PC board
(except those mounted to the enclosure).

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160 W (PEP) Broadband Linier Amplifier parts list :
C1 : 0.033 µF mylar
C2, C3 : 0,01 µF mylar
C4 : 520 pF dipped mica
C5, C7, C16 : 0.1 nF ceramic
C6 : 100 uF/15 V electrolytic
CS : 500 µF/6 V electrolytic
C9, C10, C15, C22 : 1000 pF feed through
C11, C12 : 0.01 pF
C13, C14 : 0.015 Pic mylar
C17 : 10µF/35 V nlectroiytnc
C18, C19, C21 : Two 0.068 pF mylars in parallel
C20 : 0.1 uF disc ceramic
C23 : 0.1 µF disc ceramic
R1 : 220 Ω, 1/4 W carbon
R2 : 47 Ω , 1/2 W carbon
R3 : 820 Ω, 1 W wire W
R4 : 35 Ω, 5 W wire W
R5, R6 : Two 150 Ω, 1/2 W carbon in parallel
R7, R8 : 10 Ω, 1/2 W carbon
R9, R11 : 1 k, 1/2 W carbon
R10 : 1 k, 1/2 W potentiometer
R12 : 0.85 Ω (6 5 1 Ω or 4 3.3 Ω 1/4 W resistors in parallel, divided equally between both emitter leads)
L1 : .33 pH, molded choke
L2, L6, L7 : 10 pH, molded choke
L3 : 1 8 uH (Onmite 2 144)
L4, L5 - 3 ferrite beads each
L8, L9 - 22 uH, molded choke
Q1 : 2N6370
Q2, Q3 : 2N5942
Q4 : 2N5190
01 : 1N40O1
D2 : 1 N4997
J1, J2 : BNC connactors

T1 : 4 1 Transformer, 6 turns, 2 twisted pairs of #26. AWG enameled wire (8 twists per inch)
T2 : 1 1 Balun, 6 turns, 2 twisted pairs of #24 AW enameled wire (6 twists per inch)
T3 : Collector choke, 4 turns, 2 twisted pairs of #22 AWG enameled wire (6 twists per inch)
T4 : 1 4 Transformer Balun, A&B – 5 turns, 2 twisted pairs of #24, C – 8 turns, 1 twisted pair of #24 AWG enameled wire (All windings 6 twists per inch).
( T4 – Indiana General F624-1901, – All others are Indiana General F62 / 801 ferrite toroids or equivalent.)

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Amateur Radio Linier Amplifier parts list :
C1	: 33pF Dipped Mica
C2	: 18 pF Dipped Mica
C3	: 10 uF 35 Vdc for AM operation,
	  100 uF 35 Vdc for SSB operation.
C4	: .1 uF Erie
CS	: 10 pF 35 Vdc-Electrolytic
C6	: 1  µF Tantalum
C7	: .001 pF Erie Disc
C8, 9	: 330 pF Dipped Mica
R1	: 100 k ohm 1/4 W Resistor
R2, 3	: 10 k ohm 1/4 W Resistor
R4	: 33 k ohm 5W Wire Wound Resistor
R5, 6	: 10 ohm 1/2 W Resistor
R7	: 100 S2 1/4 W Resistor
RFC1	: 9 Ferroxcube Beads on #18 AWG Wire
D1	: 1N4001
Q2	: 1N4997
Q1, Q2	: 2N4401
Q3, 4	: MRF454
T1, T2	:16:1 Transformers
C20	: 910 pF Dipped Mica
C21	: 1100 pF Dipped Mica
C10	: 24 pF-Dipped Mica
C22	: 500 µF 3 Vdc Electrolytic
K1	: Potter & Brumfield
KT11A 	: 12 Vdc Relay or Equivalent

The post 140W ( PEP ) Amateur Radio Linier Amplifier (2 -30 Mhz) appeared first on Amplifier Circuit Design.

The 100 watt linear amplifier operating from a 28 volt supply, 8 dB of power gain is achieved along with excellent practical performance featuring: maximum input SWR of 2:1, harmonic suppression more than-63 dB below 100 watts output, efficiency greater than 40%, circuit stability with a 3:1 collector mismatch at all phase angles.

100 watt linear amplifier Parts list :
Ti & T2 - Balun. Unbalanced to Balanced RG 58, I = 2.5"
R1 : 1 k, 1/2 W
R2 : 10 ohm 1/2 W
R3 : 10 ohm 1/2W
R4 : 5.6 ohm 1 W
R5 : 5.6 ohm 1 W
R6 :  2.7 ohm 1/4 W
Z1 & Z3 : Microstrip - W = 200 mils, I = 1 8"
Z2 & 24 : Microstrip - W = 200 mils, I = 300 mils
Z5 & 26 : Microstrip - W = 150 mlls, I = 300 mils
Z6 & Z8 : Microstrip - W = 150 mils, I = 1.4"
RFC 1,4 : Ferroxcube Bead 56 590-65-38
RFC 2,3 : 0,16 uH Cambion Molded Coil
RFC5, 6 - 1 Turn #20 Enameled Wire Wound on 5/16" Bolt
RFC7, 8 : VK200 20/48
C1,3,4,5,7,8,11,15 : Underwood 40 pF
C12,16 : Underwood 25 pF
C13, 14, 22, 23 : Underwood 18 pF
C9, 10, 18,20 : I uF Tantalum
C21, 24 : Underwood 10 pF
C2, 6 : Arco 403
C17.. 19 : Underwood J102. 1000 PF Feed Thru
C25, 26 : 0,1 uF, Erus  Red Cap
L1 : 24 nH, #14 Wire, I = 1.2"
L2 : 12 nH, #14 Wire, I= 0.6"
L3 : 24 nH, #14 Wire, I = 1 2"
Board : G10, cR : 5. t=0.062" , I = 8.0", W = 4.0"
Q1 : 2N5192
Q2 : 2N5194
Q3 : MRF309
Q4 :  MRF309
D1 : 1N4001

The post 100W PEP 420-450Mhz PUSH-PULL LINIER AMPLIFIER appeared first on Amplifier Circuit Design.

L1 can be chosen for the application. A 470µH coil works on lower frequencies and lie in Am, for shortwave try a 20µH coil. This AM/FM/SW Active Antenna circuit can be powered by a 9 volt battery pack. If a power supply is used, bypass the power supply using a 0.04µF capacitor to prevent noise pickup. The antenna used on this circuit is a standard 18-inch telescoping type, but a thick piece of copper, bus-bar, or piano wire will also work fine.

The post Active Antenna for AM/FM/SW appeared first on Amplifier Circuit Design.

This amplifier will pull in all distant FM stations clearly. Active FM amplifier circuit is configured as a common-emitter tuned RF pre-amplifier wired around the VHF / UHF transistor MFE201. There are several other types of transistors that will probably work as well, such as NTE107, 2SC2570, etc. but this is untested.

Adjust capacitor trimmers C1 and C2 for maximum gain. Input coil L1 is made up of 4 turns of 20SWG enamelled copper wire over the 5mm diameter former. It is tapped at the first turn from ground lead side. Coil L2 is just like L1, but has only 3 turns. Pin configuration is shown in the diagram.

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General Purpose 10 Watt Audio Amplifier Parts list :

R1,R2 : 470 ohm
R3,R4,R5 : 22k ohm
R7,R8 : 100 ohm
R9,R10 : 0.33 ohm
R11 : 4.7 ohm
VR1 : 250 ohm ( variable )
C1,C7 : 0.1uF
C2 : 0.01uF
C3 : 1uF/35V
C4 : 470uF
C5,C6 : 2200uF/35V
D1,D2,D3 : 1N4002
T1 : 2N3904
T2,T4 : TIP41A
T3 : 2N3055
T5 : MJE 2055
IC : 7812

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