Questions tagged [amplifier]
Questions about amplifiers, typically RF power amplifiers. For low-noise amplifiers (LNAs) consider using the "lna" tag.
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Question about low voltage from mains for tube amplifier 811h
Edit: So I guess what i really want to know is more technical question regarding 572b tubes. What plate voltage is minimum to safely drive 572b tubes? what is lowest filament voltage to optimally ...
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Quartz Oscillation Output Signal Amplifying for more Power?
Quartz oscillation is well known for its high Q-Factor and stable frequency. I have read many articles which say that amplifying such quartz oscillations should not be easy. I am not a licensed radio ...
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Can I operate in AM mode using an Alpha 78 amplifier?
I don't have any experience with amplifiers. I bought my first one last year, a used Alpha 78. I cannot find anywhere where it explicitly states that you can use the Alpha 78 in AM mode. I suspect it'...
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Replace transistors in MiniPA amplifier kit
I recently purchased a MiniPA 100-watt HF amplifier kit. It is a class AB push-pull amplifier and uses the MRF 9120 transistor. While doing some reading on this amplifier kit I noticed some ...
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How do I couple two VHF Small Signal Amplifiers together?
I have managed to build single stage VHF amps ok using the transistor's S-Parameters to determine the load and source reflection coefficients for a specific gain and stability considerations.
Simple ...
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What happens with LNA in bidirectional communication? [closed]
I want to ask that if you have a cable that has started with 40dbm source signal and has reached -10dbm then you put LNA (the end of the cable will be plugged to RFIN), then attach the RFOUT to ...
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Repeater Amplifiers DMR vs Analog
I have recently purchased an amplifier for my repeater. This was actually my first amplifier purchase ever and should probably have asked more questions prior to buying it. The repeater is a ...
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Why does my received power rise so much when I connect an antenna?
I am in early stages of making a narrow-band radio receiver (block diagram below). To give you an idea, I am using a simple CP-FSK based modulation scheme, and have achieved 5dB SNR with a Tx signal ...
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Connect an LTE ("4G") signal booster (amplifier) directly to my router will break it?
The goal is to connect an LTE ("4G") signal booster (amplifier) directly to my router to
avoid the radio signal feedback¹ by the LTE ("4G") signal booster (amplifier).
¹ ...
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What's the maximum possible "DC input to radiated RF" energy efficiency of a radio transmitter system?
It's simply a bromide amongst hams that you need to match the output impedance of a transmitter to the input impedance of an antenna, but I never thought through the implications of this until I came ...
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How much does a RF amplifier use of its input power?
I've been casually aware that signal gain can be added in "stages" but never really considered how that might actually work in practice. And it seems that some RF amplifiers really prefer to ...
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RFID extension cable
I am trying to build an extension cable to relay an RFID signal (125kHz) to various distances (2,5,10m). I am using 2 identical antennas at the two ends of a 75Ohm coax cable, and I also put 2 ...
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Looking for specifications for Wilson Electronics WAU 420 amplifier
Hey there helpful people I'm trying to track down some specifications on a Wilson Electronics WAU 420. I have no idea on its exact age but guessing its from the late 90's. It's likely UHF band and ...
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Really a Class C design?
In the March 2000 QST there was an article on the Tuna Tin QRP transmitter, which I thought I might build:
The text describes Q2 as a C Class amplifier, but I just can't see how that can be true.
&...
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Design of an LNA housing box for a UHF/VHF satellite ground station
I'm currently designing a waterproof metallic case to house LNAs, power cables, and RF switches for a UHF/VHF satellite ground station. As shown in the diagram below, the antennas are connected to an ...
