Questions tagged [amplifier]

Questions about amplifiers, typically RF power amplifiers. For low-noise amplifiers (LNAs) consider using the "lna" tag.

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11
votes
3answers
4k views

Why does "high SWR" damage transmitters, instead of "impedance mismatch"?

In the audio realm, where cable lengths are insignificant compared to the signal wavelength, I would understand an impedance mismatch damaging an amplifier as follows: Take an audio amplifier that ...
14
votes
3answers
2k views

What is a linear RF amplifier?

Most of the RF amplifiers advertised, and most of the questions about amplifiers, are "linear" amplifiers. What is a linear amplifier, and what other common amplifier type(s) exist that requires ...
4
votes
1answer
392 views

What is the average fade margin required for proper operation at 2.4 GHz?

I have two radios. Sensitivity is -84 dBm and transmitting EIRP is +30 dBm. How much distance should I expect? I want it to be somewhere near about 2-3 km. Is it possible?
7
votes
2answers
604 views

How to calculate if low-pass filtering is sufficient?

An answer on this question Suggested method for boosting 0.05 watt transmitter up to 10+ watts? suggests putting a filterless 19dB amplifier between the HackRF (or similar general-purpose SDR) and a ...
6
votes
1answer
1k views

Suggested method for boosting 0.05 watt transmitter up to 10+ watts?

Long time ham operator here, new to this particular challenge - I have a software defined radio transceiver that I'd like to try and use to make contacts on HF, in particular 20-meters. Tuning ...
9
votes
2answers
691 views

What is the purpose of the transformer at the input (and output) of this RF push-pull amplifier

Firstly, feel free to move this to Electronics SE if it's not on-topic, but it's strongly related to ham radio and RF circuitry. Reading Hayward's classic "Solid State Design for the Radio Amateur" ...
7
votes
1answer
129 views

Efficient BPSK31 amplification

I'm looking at making a portable system that can transmit BPSK31. I have a limited power budget, so I'm looking at trying to make my final power amplifier as efficient as possible. From my ...
4
votes
4answers
793 views

Why does an RF Amplifier fail when the SWR is high?

Exactly why does an RF output transistor fail if the SWR is bad ? Is it A because the impedance mismatch between the transmission line and the antenna results in maximum power not being transferred ...
3
votes
1answer
188 views

Reduction in transceiver power output into high SWR

How much do transceivers drop their output power, when the SWR is high? Most amateur solid state amplifiers or transceivers are (fully?) protected against high SWR, by a circuit which reduces the ...
1
vote
2answers
100 views

Toroid Coupling Issue in Common-base Amplifier

I'm working on an old school VFO for the 15 meter band based on a JFET Hartley oscillator. The plan is to follow the oscillator section with a JFET buffer, then a CB amplifier (for increased reverse ...
0
votes
2answers
153 views

sdr as watts and amps [closed]

Thanks to rclocher3 for helping edit more to English why closed so my struggle to get thought to English thank rclocher3 I round back too best I put in avuenue what I was asking why closed i tryed ...