Questions tagged [superheterodyne]

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2
votes
1answer
525 views

Frequency Display for Old Tube Radio

I have a Hallicrafters S-120 1960s vintage vacuum tube receiver (an "All American Five" superhet with solid state rectifier replacing one of the "five" tubes). It works well, doesn't have excessive ...
5
votes
3answers
650 views

Can SDR receivers be detected remotely?

It's my understanding that active superhet receivers can be detected by looking for the emissions from the local oscillator, particularly because the LO's frequency is usually set at some fixed offset ...
3
votes
3answers
103 views

What causes an AF amplifier to make popping sounds in a superheterodyne receiver?

Recently I've made a simple single IF superheterodyne SSB receiver for 40 meter band. The schematic is available here [PDF]. VFO and BFO are based on Si5351, the AF amplifier is LM386. It works OK but ...
0
votes
1answer
41 views

Combining two CFU455IT +/-2kHz (4kHz) ceramic filters to get a +/-1.25kHz (2.5kHz) filter for SSB

Can I put two of these cheap (less than 3USD) and common CFU455IT +/-2kHz (4kHz bandwith -6dB ) ceramic filters in series to get a lower bandwidth good for SSB TX? If I'm correct I will get -12dB at +/...
9
votes
1answer
323 views

How Could Superheterodyne Receiver Ever Work?

I am surprised how the Superheterodyne Receiver still works and is still in use after coming to realise the impact of Image Frequencies on its performance. Basically, I'm curious how engineers make ...
4
votes
2answers
185 views

Can a Digital Down Converter, at the same time, generate I,Q streams & Downconvert?

A Digital Down Converter (DDC) is usually used to convert Real Digital Signals at a high frequency to baseband (centered around 0Hz). DDC does this so by producing negative and positive frequencies. ...
3
votes
1answer
286 views

Seeming conflict in the definitions of dynamic range

As I understand it, dynamic range is the difference in dB between the strongest and weakest signal discernible by your receiver. So, the larger the dynamic range, the better, which seems intuitive. ...
4
votes
1answer
3k views

What advantages does dual-conversion have over single-conversion superheterodyne?

I've seen a variety of radio block diagrams, and some have two mixers inline with the signal. If the signal is already in a frequency range suitable to work with, what does the second conversion/...
12
votes
1answer
6k views

How is the IF for a superhet selected?

There seem to be almost as many choices for the intermediate frequency (IF) as there are superheterodyne receivers and transceivers out there. The ones I have come across are 455 kHz, 452 kHz, 1.6 MHz ...