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Old 22nd Jan 2018, 10:23 am   #1
ottavio
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Default Looking for a cheap and simple shortwave regenerative kit

Hi all,

I posted a similar topic to a dedicated mailing list but I didn't get the solution I needed.

I'm looking to build a simple regen receiver which can also be used as part of my practical assessment for the UK Intermediate Licence.

It can either be a commercial kit or a just a circuit, but it has to be made from commercially available components. I cannot and don't want to build my own coils.

My requirements are, in order of importance:

- cheap
- simple design
- transistors (not valves)
- lightweight (no enclosures or speakers, just the circuit)
- Ideal bandwidth from MW to 15 Mhz. If this is not possible, at least covering
from 80m to 20m amateur bands; alternatively I would consider a regen that covers the medium waves up to 2Mhz
- Bandspread should be enough to be able to tune to ham ssb stations
- If it's a kit it should be available to be shipped to the UK,
otherwise components can be bought pre made (eg coils)

I was advised to order the Walford Rockwell:
http://www.walfords.net/simple.htm

I also have the pdf of the instructions (I'm not sure if copyrights allow me to post it here). It looks like a nice and clean project, but I think this was born for the CW portion only. The circuit apparently can be made to cover either 700 KHz to 1.3 MHz or 1.4 to 2.4 MHz (for the top band); 3 to 4 MHz on the 80m and on the 40m the bandspread is only 120khz. Apparently you can only have two of the above but not all.

Otherwise other options are more complicate and expensive, like the KRC2:
http://www.kitradio.co.uk/page10.htm

It's not that I cannot afford the money but I just want something simpler.

Any input will be appreciated.
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Old 22nd Jan 2018, 11:12 am   #2
MrBungle
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Looking at the Walford kit that's about as simple as it gets really. There is the option of the very cheap transistor radio kits from China as well. Not affiliated with the seller here but this is a typical example:

https://www.ebay.co.uk/itm/263408131354

Also to note is the GQRP "sudden" kit here but you'll have to join GQRP club to get it (6 for membership and thoroughly worth it from experience): http://www.gqrp.com/sudden.htm

And if you don't fancy that, there are some projects towards the end of the following book which use "canned components" which are easy to get in the UK: https://www.amazon.co.uk/dp/1905086849

I haven't actually done the intermediate yet myself (literally just did foundation) but from what I've seen they should cover the requirements in theory.
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Old 23rd Jan 2018, 6:22 pm   #3
Bazz4CQJ
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Does the UK Intermediate Licence actually forbid the use of home-made coils; I would certainly hope not! Coil makers like Osmor, Denco, and others I can no longer recall, are long gone.

Don't be too put off by coil making. The first I made, under "supervision" by my mentor back in the '60's were no more than ~20 turns of 32 gauge wire on toilet-roll tubes, all held together with sticky tape and they worked wonderfully well in my two-valve TRF on the 30m SW band. The only "coils" I have bought in the last couple of decades have been miniature RFCs.

B
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Old 23rd Jan 2018, 6:28 pm   #4
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Default Re: Looking for a cheap and simple shortwave regenerative kit

It doesn’t. Some people just don’t like winding them. Some days I’m with them, usually after a T37-6 rolls off under the sofa
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Old 23rd Jan 2018, 6:42 pm   #5
Bazz4CQJ
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Default Re: Looking for a cheap and simple shortwave regenerative kit

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Originally Posted by MrBungle View Post
a T37-6 rolls off under the sofa
Well, it will certainly be the case that my next shack will be totally devoid of deep-pile carpet; I could lose toilet roll tubes in the carpet of the current shack .
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Old 23rd Jan 2018, 6:55 pm   #6
David G4EBT
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Quote:
Originally Posted by Bazz4CQJ View Post
Does the UK Intermediate Licence actually forbid the use of home-made coils; I would certainly hope not!
B
Well for a start off, you don't need any kind of licence to build and operate a receiver.

The Foundation licence (the only 'complete 'stand-alone' licence) permits the use of commercial transmitting equipment up to 10 Watts output. It also permits the use of 'approved kits', which isn't defined as there is no approval system, but Tim Walford (Walford Kits), for example, produces quite a range of high quality low power transmitting kits and receivers which would give no concern to Ofcom. The FL does not permit the use of modified ex PMR equipment, but that's a thing of the past anyway.

The Intermediate licence, which bolts onto the FL, allows home-brew and up to 50 Watts output. In any event, both courses involve some practical work, such as building a VFO, which hopefully encourages some candidates to have a dabble at homebrew. All in all, a far better grounding in the hobby than the old essay style RAE I took back in 1974 - what a let down that was. No practical work, and no on-air assessment.

The Full Licence bolts onto the other two, and also permits homebrew should anyone wish to engage in it, and up to 400 Watts PEP on SSB, which is a bit academic, because most amateurs use commercial transmitters with solid state PAs which put out 100 Watts maximum. But because they have built-in ATUs which will limit the output into a mismatched antenna, it's unlikely that 100 Watts will appear at the feed point of the antenna.

QRP (low power), seems to be the last bastion of 'home-brewing'.

Search PW from cover to cover and you'll find lots of glossy full-page ads with equipment that can cost as much as a small car, but little technical content. (Even Tony Nailer doesn't write for PW any more). Contrast that with the G-QRP Club magazine 'SPRAT', which cover to cover, is home-brew. QRP is defined as up to ten Watts. Surprising what you can do with that. Many QRPers manage with less - there's a 'Million Miles per Watt' award.

Have fun!
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Old 23rd Jan 2018, 7:18 pm   #7
David G4EBT
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Quote:
Originally Posted by ottavio View Post
Hi all,

I posted a similar topic to a dedicated mailing list but I didn't get the solution I needed.

I'm looking to build a simple regen receiver which can also be used as part of my practical assessment for the UK Intermediate Licence.
I was advised to order the Walford Rockwell:
http://www.walfords.net/simple.htm

It looks like a nice and clean project, but I think this was born for the CW portion only. The circuit apparently can be made to cover either 700 KHz to 1.3 MHz or 1.4 to 2.4 MHz (for the top band); 3 to 4 MHz on the 80m and on the 40m the bandspread is only 120khz. Apparently you can only have two of the above but not all.

Any input will be appreciated.
All of the kits designed and supplied by Tim Walford are excellent, and have been ''beta tested' by experienced amateurs who build the kits and highlight any shortcomings in, for example, the instructions which might fox inexperienced constructors, giving feedback to Tim to make any amendments that might be necessary.

The kit doesn't 'appear to cover only the CW portion of the chosen bands' because the info states that it has: "two general coverage bands which can be chosen from MW or around 160m, and around 80m or 40m". The description further states that "because it is a Regen TRF it can also copy the common modes of Morse, and phone Single Sideband used by amateurs".

Tim will have designed that kit with the Intermediate Licence in mind, to strike a balance between ease of construction and reasonable performance. Looks ideal for me as a first project. You'll notice for example, that all of the controls are mounted on the printed circuit board to save any complications of wiring up off-board controls for tuning and regeneration.

If you have any concerns or need further clarification, just give Tim a call and talk it through with him.

I have no connection with Tim, but some years ago I did build one of his kits, which gave a good account of itself.

Best wishes with the Intermediate Licence.
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Old 23rd Jan 2018, 7:49 pm   #8
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Why go for a regenerative receiver? Unless you really know what you're doing [including having the ability to produce the necessary shielding metalwork] they are generally horribly troubled by hand-capacity/swaying-antenna effects when trying to resolve CW or SSB amateur transmitters.

I'd suggest instead looking at the likes of the "Halse" and "Hatch" - http://www.walfords.net/intermediate.htm

What starts off as a simple single-band SSB/CW receiver [Halse] then converts into a 5-Watt SSB transceiver by adding the 'Hatch' board.

[I'm minded to build a Halse/Hatch for myself, putting it on 5MHz for some portable ops when the Clansman PRC320 and its batteries/carrying-frame are just too heavy.]
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Old 23rd Jan 2018, 9:43 pm   #9
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Default Re: Looking for a cheap and simple shortwave regenerative kit

I would endorse what previous posters have said about the GQRP club and look at past issues of SPRAT they have some nice designs for simple receivers and the club have a shop that can supply some of the components.

Dave
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Old 24th Jan 2018, 10:04 am   #10
ottavio
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Quote:
Originally Posted by G6Tanuki View Post
Why go for a regenerative receiver? Unless you really know what you're doing [including having the ability to produce the necessary shielding metalwork] they are generally horribly troubled by hand-capacity/swaying-antenna effects when trying to resolve CW or SSB amateur transmitters.

I'd suggest instead looking at the likes of the "Halse" and "Hatch" - http://www.walfords.net/intermediate.htm

What starts off as a simple single-band SSB/CW receiver [Halse] then converts into a 5-Watt SSB transceiver by adding the 'Hatch' board.

[I'm minded to build a Halse/Hatch for myself, putting it on 5MHz for some portable ops when the Clansman PRC320 and its batteries/carrying-frame are just too heavy.]
That kit would definitely not be accepted by my club as it is too complicated. Our trained originally said it definitely must be a VFO kit. This is why I want to find a simple alternative.

If the kit was for my own use only, I'd definitely spend a bit more money and build either the BITX or the BITX40.
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Old 24th Jan 2018, 10:33 am   #11
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Did some research for this just now as I'm going to have to do the same thing. I have all the bits lying around though, and a couple of VFOs I've already built...

There was someone selling a VFO kit specifically for this, but as you can see, it's no longer for sale: http://www.tuckley.org/vfo/

Jabdog sell a complete kit for a VFO only. This might be a good option for you! See: http://www.jabdog.com/kits-txrx.htm

However a note: such is life and it's pretty difficult to throw together a VFO these days because of parts availability. The original varicaps/varactors specified tend to simply not exist these days or be tiny SMD parts. Air variable capacitors are dead and gone. Polyvaricons are terribly unstable, fragile and unreliable. Everything is heading towards cheap digital synthesizers such as AD9850 variants or Si570's. I rather like the latter as you can get it to generate the VFO and BFO frequencies.

RSGB does however have some advice here as they seem to be way behind the times and backtracking: https://thersgb.org/publications/boo...ediate-vfo.pdf

Just a point with the hfsignals kits; they are actually already complete and you are only required to attach the various control tentacles to the board and throw it in a box. That wouldn't cover the requirements to build and align the VFO as it's prebuilt and pre-tested.

Here's a VFO I did yesterday to evaluate using LEDs as varactors, because they're cheap. Add a 10 turn pot (9) with some pad trimmers and you have a nice tuning system. This tunes low half of 40m (7000-7100khz):

Click image for larger version

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I think this is about 2's worth of parts and this has a power amp on it too.

A point with clubs though, at least in my experience, is that the few people I've talked to would never have actually built a VFO in their life so some of the advice isn't necessarily good. Always double check it elsewhere. Also there's a lot of religion in this stuff which makes no sense whatsoever.
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Old 24th Jan 2018, 10:53 am   #12
Ted Kendall
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Default Re: Looking for a cheap and simple shortwave regenerative kit

I like the breadboarding method - never thought of doing it like that - sort of bird's nest but with a ground plane. Neat!
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Old 24th Jan 2018, 11:07 am   #13
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Default Re: Looking for a cheap and simple shortwave regenerative kit

It works pretty well. Traditionally called "dead bug style" as the ICs are usually upside down with legs up. Here's another one I did which is a whole receiver: https://www.vintage-radio.net/forum/...d.php?t=139481

I'm not sure the obsessive compulsive organiser in me can cope with it though in the long term so I've started looking at other methods. It's fine for prototypes but I need something that I know doesn't look too horrible inside. I tried Manhattan style but it's too fiddly and takes too long. Currently settling on a style I saw somewhere which is untitled AFAIK where you use the copper top as the ground plane, drill all the holes through and then countersink them, then wire up all the parts via leads on the bottom. That's nice and neat and doesn't require PCB manufacture.
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Old 1st Mar 2018, 10:09 am   #14
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Default Re: Looking for a cheap and simple shortwave regenerative kit

I ended up ordering the Rockwell from Tim Walford and I started building it a couple of days ago. I have to say I'm struggling a bit. The instructions are quite terse and you need to read them a couple of times or maybe 3 or 4. The PCB is not marked, like a standard kit. You have to deduce where to solder the parts from the pictures provided (but I have a pdf colour copy, courtesy of http://www.learnmorsecode.com/regen/WALFORDS/index.html) and the hand written schematics. Note that the owner of the above mentioned site has also played around with the kit, something I plan to do later on.
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Old 1st Mar 2018, 10:31 am   #15
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Default Re: Looking for a cheap and simple shortwave regenerative kit

First time you do these they are hard. Very hard. Much head scratching will ensue. But there is a light at the end of the tunnel; they do get easier. Even if you make a mistake or two, which I do regularly even after building kits for about 30 years, it's always salvageable. If you get stuck, or something doesn't work, please post back. This forum I have found has many terrific people who are willing to help.

Also to note as a contrast, the pinnacle of such things is the Chinese radio kits which either ship without instructions entirely or you find that the instructions are in Chinese or are entirely wrong or for something entirely different. This results in an hour googling what colours are in Standard Chinese so you know which IFT to stick in which hole and then still get it wrong and the output stage explodes in your face. This happened to me recently. It took me a week to get it working. Persistence pays off!
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Old 1st Mar 2018, 6:45 pm   #16
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Default Re: Looking for a cheap and simple shortwave regenerative kit

have a look at the spectrum communications site. there is/was a simple regen kit there for sale . a collaboration with g3rjv . also the collected articles on cd by g3rjv 20 years of practical projects in practical wireless. a mine of information.regards ei7ka
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Old 1st Mar 2018, 9:27 pm   #17
David G4EBT
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Default Re: Looking for a cheap and simple shortwave regenerative kit

Quote:
Originally Posted by MrBungle View Post

Jabdog sell a complete kit for a VFO only. This might be a good option for you! See: http://www.jabdog.com/kits-txrx.htm
I think this is about 2's worth of parts and this has a power amp on it too.
Though the link to that Jabdog website still works, you'll see that the webpage was last updated on 9th June 2011. For some years now, Peter has run his business as an ebay shop, the link to which is here. Many of the items he used to stock, which are listed on the defunct webpage have been obsolete and no longer available for some years now. For many years Peter used to have a full page add in 'SPRAT' magazine, but again, that went by the wayside some years ago.

Here's where JABDOG is now:

http://stores.ebay.co.uk/JabDogElectronicComponents

As to designs for simple regenerative receivers, they often appear in SPRAT, but rarely with full constructional details suitable for a raw beginner.

QRP is really the last bastion of home-brew and SPRAT is a 'cookbook' for experienced home-brewers. As an example, in issue 170 - Spring 2017, there was a design by a French radio amateur (F5LVG) for a 'High Performance Regenerative Receiver'. It covered five amateur band - 80,40,20,17 and 15 Metres, using self-wound high-Q plug-in coils on 22mm diam plastic tube formers, for which winding details were provided. (only one coil per band with no taps). The devices used are 1N4148 x 4, 1N4007, BF199 x 2, (RF Amp and regenerative detector), BC547 (AF pre-amp) amd a TDA2003 AF Amp.

But as far as this thread is concerned, this design has little relevance.

It does meet the criteria of being cheap, it's high performance, it's as simple as could be consistent with good performance for an experience constructor, but it does not meet the criteria of being simple to build for someone studying for the intermediate licence so as to meet the requirement for demonstrating practical skills. Anyone wishing to build it would need to design their own layout and means of construction. Often, that's 'ugly style/dead bug/Manhattan' or less often, a self-designed PCB, which the SPRAT 'F5LGV' design would lend itself to. Along with a homebrew QRP transmitter, the designer had several SSB contacts from France with North American amateurs.

If there are any problems in building the Rockwell, Tim Walford is at the end of a phone and on e-mail, and would I'm sure be happy to help in any way possible. Bear in mind that the Intermediate licence permits the licence holder - should they have a mind to - to design, build and put on air transmitting equipment using up to 50 Watts, so at least a minimal understanding of how transmitters work, and a minimal level of practical skill and experience is called for.

This tends to be self-regulating - if someone either doesn't wish to build transmitting equipment or doesn't feel competent, they don't do it - the reality is that as with the full licence, in the time poor/cash rich society in which we live (relative to yester-year), most amateurs use out-of-the-box equipment, some of which costs as much as a small family car, but that's a personal choice, not a condition of the licence.

In this - as in any other hobby - people will do what interests them most, whether it's just going on air, home-brewing, or a bit of both.

To enjoy driving a car, you don't have to build it from a kit.
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Old 5th Apr 2018, 9:24 am   #18
dalekmoore2007
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Default Re: Looking for a cheap and simple shortwave regenerative kit

I don't know if you know of the old Tandy electronics science fair kits which i started my electronic construction with .
http://my.core.com/~sparktron/pbox.html
PDFS here and there is a simple SW radio as wanted i made many a time
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