Is there an 'industry standard' for a receiver?

[kellys_eye]

When 'ah were a lad...... the 'industry standard' for radio constructors was the ubiquitous crystal receiver - and much fun was had building and using one.

But as things progressed there became a plethora of single tube, single transistor, single IC etc designs that were touted as 'introductions' to radio receivers but was there ever a standard that became as popular as the good old crystal set?

I ask as I have been talking to younger enthusiasts who have queried along the lines of 'what valved (and even transistorised) receiver do you recommend I build first'.

If you were to recommend anyone considering their first valved set what would you say - based on today's parts availability of course?

[G3PIJpeter]

Originally Posted by kellys_eye

If you were to recommend anyone considering their first valved set what would you say - based on today's parts availability of course?

Start here http://www.w7ekb.com/glowbugs/rx/Regens/regens.htm and adapt according to parts available e.g. polyvaricon rather than air-spaced variable capacitor.

This one http://www.w7ekb.com/glowbugs/rx/Reg...at7_regen.html avoids a tickler feedback coil, using a pot to control feedback.

Peter

[paulsherwin]

I still think a crystal set is a good first project. There's less to go wrong, so it builds confidence. After that, a crystal set with a simple one transistor AF amp.

It's a bit bonkers to suggest to an absolute beginner they build a valve radio nowadays. The technology has been obsolete for several generations so will be completely alien, and there are practical problems with things like power supplies and high voltages.

[joebog1]

Is this actually a serious question??
I made my first crystal set by burning sulpher powder with lead filings.
Smell was HORRIBLE and probably deadly. THEN I had to make a springy thingy to find a "sweet spot" on the (supposedly ) lead sulphide I had made.
It worked !!! .

I still have the origional headphones I used back then.
Later, when I could afford a OA91 ?? maybe OA 71, I made a "portable". Clip it to any fence wire and our one and ONLY station romped in!!.
The station was 2XL, whose real call sign was: To Excel.

I have a 5 year old grandson, who will be taught about crystal sets the next time he visits Pa ( thats me ). I will cheat and use an OA 91, as I have hundreds of them.
Headphones WILL be the origionals!!!.

It is a REAL pity medium wave is almost dead!!.

With repect to all,

Joe

[joebog1]

2XL was 920 Khz. Now modified to 8KHz bandwidth and 922 Khz.

j.b.

[SiriusHardware]

I still think a crystal set is a good first project.

The biggest problem there is you could end up with a perfectly good crystal set with nothing to pick up, which would be a bit disheartening. Even back in the early noughties I recall my then partner buying a crystal radio kit as a 'scientific toy' for her son and the problems we had getting it to receive something despite a good earth and very long longwire aerial - they were basically just not in the right location.

I used to have committed to memory a 2- transistor TRF receiver, the first stage was some kind of regenerative receiver, the second was a single stage audio amplifier (output was to headphones only). I was a bit of an insomniac during my early teens and spent many hours listening to James Whale's late night phone-in programme on Metro Radio on exactly that circuit.

Until recently I would have encouraged someone to go to Maplin to buy a chip-based FM receiver kit - guaranteed to have something to receive if it works - now I suppose I would have to point them to something similar online.

[commie1]

Hi,

Whilst a crystal set will get you interested, you quickly realise its limitations. I would argue, that the industry standard radio of all time is the original war time receiver, the HRO. This receiver is the minimal receiver system that you can get away with. The trick is, to replicate it using solid state fets. I have actually done this a few years ago with limited success.

The biggest problem I hit was trying to find a fet which had the a gm as low as 1.6mA/V as per the 6d6 original valves used, you also need a 4 ganged variable capacitor, which are not easy to source.

[paulsherwin]

Replicating an HRO is hardly a beginner's project though

[kellys_eye]

'Industry standard' is of course tongue-in-cheek but we all cut our first teeth, as far as radio goes, along the lines of a crystal set and we need to acknowledge their limitations despite the practicality and simplicity of using them as a starting point.

Perhaps the best way to ask this question would be 'ok, what's the next step?'. And I was hoping there was an 'industry standard' answer such as XYZ's single-valve regen receiver, or 'WHO's transistor TRF'.

Using a crystal set as a common starting point it seems as if divergence starts immediately thereafter and the routes are almost infinite but there must(?) be a version of the-next-step that became commonplace and adopted as, perhaps, the standard of the day? Maybe I'm completely wrong?

Assuming an error in my thinking I'm still inclined to ask 'what would you recommend as the next step?' since I'm sure some members have had surprisingly excellent results from simple arrangements that could (hopefully) be replicated today??

[paulsherwin]

I don't think there was, or is, a standard approach. The reflex designs tend to be rather complex and difficult to understand for a beginner. There are plenty of simple AM designs if you google, and choosing one is down to personal preference.

I like this 'Radio 2 tuner' from the Dick & Smithy column of Radio Constructor (May 1972): http://vintageradio.me.uk/radconnav/...72/circuit.jpg Unlike many beginner's projects it might actually be of some use, and could easily be modified to work with different stations. Importantly for a beginner, it's very obvious what's going on. You could turn it into a standalone radio driving a speaker by adding an LM386 stage, which would be a good introduction to ICs.

[AdrianH]

Sorry to quote something on Ebay but why not buy a radio kit for the kids something like item number 255085285961

It is low voltage, you can help with the soldering and at the end it is cased and portable?

Not tried one but may well do.

Adrian

p.s.
Just looking at what else the seller has and looks like there is a few options and located in England.

[Andrew2]

I'd avoid reflex designs as they are a bit convoluted as Paul says. Also difficult for the beginner to get his/her head around. It's an unnecessary complication these days, as they only came about in order to save on the cost of another transistor/valve. Transistors are so cheap now that it's easier to just shove an extra stage in.

[Mark1960]

I think a simple crystal radio using a diode and crystal earpiece would be a good demo for a beginner. Headphones might be thought to be hiding something complicated. This also demonstrates that radio waves are a form of energy, no battery required.

I guess the problem nowadays is that even something the size of an earphone can have a computer and battery inside.

[Radio Wrangler]

Beyond the crystal set, what is there?

George Dobbs' Ladybird books radio?
There were battery valve designs in Meccano Magazine and Hobbies Ltd's annual in te sixties.

The HAC kits

Transistors, even valves, are available. I suppose Denco coils would be a show-stopper. Variable capacitors could be difficult.

How about an up-converting superhet with a lowpass front end. LW and MW in one fell swoop like those Armstrong tuners?

Maybe high capacitance MVAM type diodes and a nobbled car radio design.

I'm just trying to think of ways around components which are no longer currently made.

David

[G.Castle]

A young friend built this circuit, it works very well indeed, despite it's low component count. The headphones were made from earpiece drivers out of old telephone handsets mounted in ear defenders.

[Hybrid tellies]

In my younger days, back in the early 1970's, living in the more remote part of west Cornwall the only AM radio signals available to us were BBC Radios 2 and 4 joined by Radio Luxembourg during the evening. I learnt that on some radios, especially those from the Far East, if you tweaked the trimmers on the tuning capacitor you could make Radio 1 on 247m audible. I did this for my little Hong Kong special and also on some friends Hong Kong specials, ok it made the low frequency end of the MW band deaf but nobody cared as there was nothing of interest at this end of the band.

So my earliest experience with radio was not by building a crystal set or constructing a radio from a kit but trying to improve the performance of the cheap and cheerful radios from the Far East.
I have to admit I learnt a lot from this and launched my long term interest and my career in TV/Radio servicing.

Coming back on topic I noticed the big difference between the performance and sensitivity of a short 6 transistor superhet, which most transistor radios were back in the day and the more expensive better quality radios which were generally a normal 7 transistor superhet. That one extra transistor used as an AF Amp made all the difference. I have always wondered what the overhaul gain is of a short superhet and normal superhet radio and if there were any industry standards for this.

[commie1]

Originally Posted by paulsherwin

Replicating an HRO is hardly a beginner's project though

Sorry for the late reply, I'm afraid good working communications receivers, like the HRO, are never simple and require exquisite design expertise period.

Cheers
Darren

[G6Tanuki]

Crystal-sets are all very well, but what is there remaining to listen to on the frequencies/modes they cover? Llarreggub, as they would say in "Under Milk Wood".

The modern version of the xtal-set and the regenerative-TRF, I would suggest is the "Direct conversion" receiver; it's far better able to deal with resolving SSB [which is still quite commonplace on the HF bands].

The 'really modern' version being something that resolves a slice of your band-=of-=choice into I- and Q-components to feed into the soundcard-port on your PC/phone/tablet. Such a 'resolver' can be made surprisingly cheaply [see the 'softrock' kits available online] and the rest is then just software to decode your various communications-modes.

[commie1]

Originally Posted by G6Tanuki

I would suggest is the "Direct conversion" receiver; it's far better able to deal with resolving SSB [which is still quite commonplace on the HF bands].

If you standardize on 1uV r.m.s. sensitivity then you or anyone else can do this on 160m and 80m, with direct conversion, if however, you try and shoot for 1uV on 40m and downwards, you will not get it right, you will end up with an audio oscillator.

If direct conversion were truly viable, the Japanese would be using in their designs long ago.

Cheers
Darren

[kellys_eye]

Originally Posted by G6Tanuki

The modern version of the xtal-set and the regenerative-TRF, I would suggest is the "Direct conversion" receiver; i

That's kind of where I'm at right now. Siimple, practical and useful - all aspects that encourage construction and operation.

If I was to answer my own query then I reckon a DC receiver would be the 'standard' - which will probably bring about much discussion! (I hope).