Talk:Superheterodyne receiver

message: * Superheterodyne receivers usually contain double tuned circuits (sets of two loosely coupled circuits) as filters in IF receiver - this is because such a filter has almost flat band instead a peak - filtering a signal through many "peak" filters would severely distort it. Seems these tuned circuits are not even mentioned on English Wikipedia, and I am not sure what is their preferred name - is it the "double tuned circuits", or another one?
* There were many different AM IF frequencies used after II World War: in Poland there is 465 kHz standard, in GDR most receivers has 468 kHz, but there were also 440 kHz (Beethoven) and 473 kHz (Undine EAW 7695E) - from engineer's handbook (Poradnik radio- i teleelektryka, PWT Warszawa 1959, Poland) where 42 receivers are briefly described ... which countries used the 455 kHz said here?
* Except image frequency receiving, I recall two other problems these receivers have: larger noise (because mixer both produced own noise due to "sampling", and it catched noise at image frequency produced in RF amplifier), and tuning both input RF filter and oscillator circuit in a way that their frequencies keep constant difference (there was e.g. three-point tuning - for three RF-s of a band the RF filter and oscillator were tuned correctly, for any other RF there was some mismatch). And design of such a receiver requires a lot of work - it is not a receiver an amateur can build in a day or two, unless he has detailed information how to tune it correctly; it is suitable to design such a receiver for mass-production, when high cost of design has little effect on price.
* In "Overview" (near end): "The oscillator also shifts..." - I think the mixer shifts, not the oscilator.
JerzyTarasiuk 19:14, 10 November 2007 (UTC)
replies: text: For television receivers, the IF amplifiers have to be flat for the whole bandwidth, maybe 4.5MHz, of the video signal. That is much wider than for AM or FM radio. Gah4 (talk) 19:41, 30 April 2018 (UTC)

text: Actually, I just remembered that this is wrong. (Well, some days ago ...)  For analog TV, the IF has to undo the effects of vestigial sideband modulation, such that the result is flat from the video input to the modulator.  The response, then, is two flat parts with a transition in between. Gah4 (talk) 23:15, 4 February 2019 (UTC)
thread_title:  Double tuned 

message: Are these images of any use to the article?
If so please cut and paste to article page. Traveler100 (talk) 06:05, 24 August 2008 (UTC)
thread_title:  With regards requestphoto 

message: Would whoever recently pasted large lumps of technical explanation into the text please stop doing that. The History section does not need to go into such extreme detail; you're simply making it harder to follow. There are places for that further down. Ultramince (talk) 02:20, 26 February 2009 (UTC)
thread_title: Edited History Section

message: This was a standard frequency long before ceramic resonators were common - for example, the RCA "Radiotron Designer's Handbook 3rd Edition" says frequencies in the range 450-460 kHz were common, and that edition is from 1942. --Wtshymanski (talk) 17:40, 1 September 2009 (UTC)
thread_title:  455 kHz for medium-wave AM broadcast receivers 

message: Why superheterodyne receiver called super...........  —Preceding unsigned comment added by 58.68.8.190 (talk) 12:40, 7 November 2009 (UTC)
replies: text: 'Cause it's super.  More seriously, because the heterodyne (beat) frequency is above (super) the audible range. Unlike an earlier version of the detection technique, where the heterodyning oscillator is on the same frequency as the input and beats it down directly to audio. This works, but has drawbacks too numerous to describe here. Hmm, does this need to be more explicitly described ? --Wtshymanski (talk) 22:17, 20 November 2009 (UTC)

text: Until now, I always thought it was because Armstrong previously build heterodyne receivers with oscillating amplifiers. I don't know the exact details, though. So the new invention was super (better) than the old one. Now I am not sure. Gah4 (talk) 19:44, 30 April 2018 (UTC)
thread_title:  Why super ?? 

message: There is a template on Intermediate frequency proposing a merge here.  I am not so sure this is a good idea, I suggest that the proposer states the case for merger here before anything is done.  Also it is normal in proposed mergers to put a template on the proposed target article as well with a link to the same discussion. SpinningSpark 18:18, 29 November 2009 (UTC)
replies: text: I oppose this merger.  Frequency upconversion and downconversion using intermediate frequencies is a common technique in communications engineering, widely used in many devices besides superheterodyne receivers, such as radio transmitters, modems, cable television systems,  radio repeaters,  microwave radio relays,  satellite transponders,  fiber optic communication systems, cell phones and cellular base stations, telemetry systems, and microwave test equipment.  --ChetvornoTALK 19:39, 29 November 2009 (UTC)

text: This does not look like a good idea to me either. The Hetrodyne article would be a better merge destination candidate but I don't support that. I do support some other heterodyne merge proposals  --Kvng (talk) 17:51, 30 November 2009 (UTC)
replies: text: Oppose = the article is about a receiver, not just a circuit module component.Francis E Williams (talk) 16:55, 17 January 2011 (UTC)

text: OPPOSE. I am sure that there are many articles that overlap enough that they should merge, but I don't believe that this is one.  This article should contain enough details about IF to follow the rest of the discussion.  The Intermediate frequency article should include details not needed here.  The IF section of this article should not be excessively detailed, or excessively simple, compared to other sections. Gah4 (talk) 05:40, 4 February 2019 (UTC)
thread_title:  Proposed merge of Intermediate Frequency 

message: The article contains the same informaion in many of its sections, it needs to be restructured slightly and some sections rewritten to clarify what is being said.Francis E Williams (talk) 15:19, 17 January 2011 (UTC)
replies: text: You'll find the Wikipedia chief editor's Telex and FAX numbers on the home page; using either of these media, you can request the forms to make an editorial change to the article. Please allow 4 to 8 weeks for the submittal to be considered at the next editorial committee meeting. Rememmber, all manuscript submissions must be typed double-spaced, pica font, with a new fresh ribbon on 20 lb paper, on only one side.  Please enclose a self-addressed stamped envelope with your submission in case it is rejected by the editorial committee and you want your manuscript back.  --Wtshymanski (talk) 15:35, 17 January 2011 (UTC)
replies: text:  Thank you for the information. I have since received a suitable responce via UPS and have uploaded the approved content accordingly. My submission was approved on the basis that it did not remove any content, but was simply re-ordered it into a logical more readable sequence.Francis E Williams (talk) 16:52, 17 January 2011 (UTC)
replies: text:  The joke "They must be in a hurry; they Fedex'd you a FAX machine" is meaningless to today's Twitterati. And 07 57506 was the compnay Telex number, a generation ago when dinosaurs ruled the Earth. --Wtshymanski (talk) 17:26, 17 January 2011 (UTC)
replies: text: The invention of the 3D printer has been a Godsend here in my village.Francis E Williams (talk) 17:33, 17 January 2011 (UTC)
thread_title:  Duplication of content 

message: Yes, conceptually the local oscillator and mixer are two separate things, but every practical Am broadcast band receiver that I have ever worked on, or even just seen a circuit diagram for, had the one transistor being a combination mixer oscillator.
121.217.52.34 (talk) 07:40, 10 June 2013 (UTC)
thread_title:  Separate/combined mixer/oscillator. 

message: While I don't doubt that a little security might have been a consideration, a larger one is illustrated by the...um, illustration.  Wax potting prevents corrosion in wet and salt environments.  The wax melts out quite easily, and is useless to prevent commercial espionage.  Anmccaff (talk) 17:22, 22 February 2016 (UTC)
thread_title:  Wax potting 

message: what is your objection to the diagram? --ChetvornoTALK 20:29, 31 October 2016 (UTC)
replies: text: It's too busy and confusing. I've inserted the diagram and caption as they were in the article. It's a figure where one must already understand what is going on in order to appreciate it; I don't think it is clear to one who is learning. The diagram plots multiple signals (baseband, IF, LO, RF) on the same axis; that's confusing. You know how the signals are used, so you can separate them out in your mind. That's not the case with someone who does not know what is going on. Is the LO received along with the image and RF? LO and RF convolve to produce a result, but they are not present in the same signal. Why is the image a dashed CW frequency more reminiscent of the LO and not looking like another, undesired, station? Is the image another oscillator? The figure has multiple operations described without separating them. Consider plotting separate signals that are tied to the signals in the block diagram. In addition, the figure implies a specialized source (DSB) in a general situation; what about CW, SSB, and FM? The figure focuses on the artifact issue (image rejection) while ignoring primary asset of high selectivity. The heterodyne didn't leave any work for the IF filter (only one station needs to be filtered). Glrx (talk) 21:55, 31 October 2016 (UTC)
thread_title:  Frequency spectrum diagram 

message: Not sure why a large amount of martial was added to the EL section, seems way beyond MOS. If its sub-material from the same site, link only the site (WP:ELPOINTS #4).  If its a mass of martial on an alternative view to correct a "poorly sourced and skewed" history section, well, the EL section is not the place where you do that (WP:ELPOV).  If this is material from reliable sources then it should be added to the "History", not the EL section. Fountains of Bryn Mawr (talk) 22:56, 4 July 2017 (UTC)
thread_title:  Article text in the EL section 

message: Intermediate-Frequency (IF) amplifier should be merged with this article with any unique content added.;  As a stage of a superhet receiver, the amplifier has little or no independent notability and would always be discussed in context of a receiver. This article has more description of the IF amp than the proposed merge source anyway, so there may be very little that needs to be added here. Discussing all the stages in one place gives a more comprhensive overview of the topic and doesn't waste the reader's time clicking on links that give no additional useful information. --Wtshymanski (talk) 20:26, 30 January 2019 (UTC)
replies: text: As with Intermediate frequency, I thought that the more theoretical descriptions would go here, and more practical ones in Intermediate-Frequency (IF) amplifier.  As this one is already pretty long (are there suggested guidelines for article size?) some details might move out of this one.  It seems to me that readers often would be more interested in the theory, or more interested in practical descriptions, (even historical ones), so the separation would be useful. Details like the tuning of an IF strip for a vestigial sideband receiver aren't here, and might be too specific to go here.  (The response has to correct for the different amplitude of the two and one sideband frequencies, after demodulation.)  Details on the pentagrid converter are also more practical than theoretical, for example. Gah4 (talk) 02:22, 31 January 2019 (UTC)
replies: text: The nutshell description at Wikipedia:Article_size says "Neither too long nor too short" which is such a Wikipedia thing to say.  The numeric guideline is 4000 to 7000 words of readable prose. This article is just under 5000, so it's creeping up on the limit ( but probably needs editing which would bring it back down again).  Agree, if Intermediate-Frequency (IF) amplifier persists it would be the place to put the finer details, with a good overview left here - but how much more detail can you put into an encyclopedia article before it becomes a how-to guide or a textbook? --Wtshymanski (talk) 16:05, 31 January 2019 (UTC)

text: Support, for now -  you made some good points, but I think the amount of information does not justify a separate article yet.  When this article becomes larger it can be split off.  We also have Radio receiver design for this content.   Vacuum tubes, pentagrid converters, double-tuned transformers, and "aligning" an IF strip are mainly historical subjects which could go in History of radio receivers.  Modern receivers use ICs and crystal or ceramic filters, and increasingly digital IF signal processing.  These are the subjects that really need more coverage.  --ChetvornoTALK 20:35, 31 January 2019 (UTC)

text: The section names in the "Principle of operation" section  should follow standard superhet terminology; the "Amplifier" section should be renamed "IF amplifier".  There are several amplifiers in a superheterodyne. --ChetvornoTALK 20:35, 31 January 2019 (UTC)
replies: text: I believe alloy transistors means Germanium, so some years ago.  But yes, I believe that there is enough for the article. I don't know how fast it will be written, though. Gah4 (talk) 23:21, 4 February 2019 (UTC)
thread_title: Suggest merge January 2019

message: Regarding a recent edit from IF amplifier to IF filter, some might mention tuned amplifier.  Also, somewhere there might be indication of the design of IF amplifiers flat over the IF bandwidth, and dropping somewhat fast outside. This is especially important for TV, with the larger bandwidth. Gah4 (talk) 14:52, 20 November 2019 (UTC)
thread_title:  [[tuned amplifier]] 

message: There is a recent edit, and edit summary, regarding SDR and direct conversion. As well as I know, there are a few different ways to build SDR. One is to digitally, (software controlled) generate a LO, then input that into the usual analog mixer, and digitize the output. That is pretty much how the GS1299 described above works. The data sheet only says "low IF", and I don't find it on a patent, either. I believe it then digitizes the low IF, and digitally demodulates the FM signal. After that, it has to digitally demodulate the FM stereo signal. The only frequency reference is a 32768Hz crystal, from which it generates all the needed frequencies.  
Some SDR articles suggest directly digitizing the RF. Except at lower frequencies, maybe medium wave AM radio, direct digitizing at RF isn't easy.  And digital mixers at VHF or higher is not easy, either.  Gah4 (talk) 08:25, 11 May 2023 (UTC)
thread_title:  SDR with analog mixers