10m Simple Sideband

Before my 2013 stroke, I was working on a simple rig for 10m. At the time I was thinking of a dead simple DSB transceiver, but these days a better approach might be an SSB transceiver based around an SI5351 or similar synthesiser.

Whatever the approach, I had in mind a very simple, low cost rig on a single PCB.

10m is very good again and should be good for several years. It is good for Es most summers even in sunspot minimum years. It is also good for local natters. Antennas are small and CB verticals work well.

Such a simple design would make a low cost club project. When built, such a rig could be very useful especially if made as a synthesised SSB rig.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/10m-simple-sideband.

DSB v. SSB

Now, I am very happy to be told I am wrong, but I think DSB rigs can be received on other DSB receivers, but it is much more tricky than receiving DSB on an SSB receiver. I have no experience of this, but a comment on a post yesterday has me thinking. The comment was made by Ken G4APB. Thanks Ken.

Clearly a simple SSB 10m transceiver (if very low cost, simple and easily copied) would be much preferable to a DSB transceiver, but I am unsure of the relative costs.

If you have experience, please let me know. 

Clearly, if 2 DSB transceivers can not (easily) communicate, maybe a simple 10m DSB transceiver is not as ideal as a club project, even though most QSOs would be with SSB stations.

I wonder how inexpensive a 10m SSB transceiver can be made as a simple kit?

10m simple (not necessarily single) sideband transceiver

10m is coming back to life. 

At any point in the solar cycle it can be good for Es contacts (in the Es seasons especially) with low power and simple antennas. This autumn we could well see some real F2 DX more commonly on 10m.

One of my aims in the past was to design a very simple rig for 10m sideband that almost anybody could build. Sadly, my health got in the way and even this is probably beyond me now. Others may well have better ideas. All I want is someone to have a go. 

I can see a simple 10m kit in my mind that could be built at really low cost on a single PCB with a simple case. All this to allow everyone to get on 10m phone for less than the cost of one meal out (remember those!?).

My (dated now) ideas were here.

10m Simple Sideband

In the next 12 months, 10m is returning as a great DX band. At any part of the solar cycle it can be good for Es contacts in April- August in the northern hemisphere. There is a smaller Es peak in the depths of winter.

When I was fitter, I had the outlines of a simple single band QRP rig for 10m. My idea was DSB based as this was simpler. This was to be paired with a direct conversion RX.

Then my 2013 stroke happened and all development work stopped. 7 years later there may be better options. My hope is that someone else will take this on and try to create a simple, single board, single band transceiver.

See https://sites.google.com/site/g3xbmqrp3/hf/10msimple_sb

QRPguys DSB rigs for digital modes

Practical Wireless has a piece on a tiny, low cost, DSB rig kit that is ideal for digital modes like FT8. The article is written by Martin Peters G4EFE.

This is a QRP transceiver producing the equivalent of 500mW at least of SSB. On digital modes like FT8, this is capable of worldwide QSOs.

Being DSB, half the power is wasted, but this makes the rig very simple. On WSPR it would be even better, although there are far more people using FT8 than WSPR.

See https://qrpguys.com/

10m Simple Sideband

My health has not been good for over 5 years, so work on this project stopped sadly.

The ideas were good ones and I am sure there is mileage for someone to progress these. What I really want is for someone to take this on and produce a really simple kit including a PCB and all the parts.

Every summer, such a rig would work right across Europe on 10m. In a few years real DX should be possible with modest wire antennas.

It would make a nice club project. First of all, someone needs to finish the development!

See https://sites.google.com/site/g3xbmqrp3/hf/10msimple_sb

Micro 40 - 40m DSB transceiver

See http://home.alphalink.com.au/~parkerp/projects/projmicro40.htm .

Also: https://aa7ee.wordpress.com/2013/10/19/the-vk3ye-micro-40-dsb-transceiver/ .

Well designed DSB transceivers are much simpler than SSB rigs as no SSB filters and mixing to final frequency is needed. They must not be over-driven to avoid a spreading signal. The PA needs to be linear too. These issues being carefully considered, you end up with a rig that has the same bandwidth as an AM rig but with a suppressed carrier. DSB transmitters are usually received as an SSB signal. The downside is that if a simple direct-conversion receiver is used then there is no rejection of stations sitting on the other sideband. So, they are best on quieter bands, rather than busy HF bands. Bands like 10m, 6m and 4m are probably good candidates.

Although not impossible, it is quite difficult to demodulate a DSB signal on a simple direct-conversion receiver. DSB rigs are ideal as simple transceivers to communicate with SSB rigs.

10m 3 transistor DSB transceiver

In case you missed this:

http://www.cqpub.co.jp/hanbai/books/15/15061/15061_p.180-181.pdf

This gives the schematic and lots of data in Japanese.

All RF circuit inductors could be replaced by small  (T50-6 or T37-6) yellow toroids and variable caps.

10m 3 transistor DSB rig video, and more on the Minima

Stephen G7BFY sent me a link to a video on YouTube of the Japanese 3 transistor DSB transceiver featured in this blog some years ago. It is being tested by some Italian stations over a 10km path. Sorry this video is in Italian.

See https://www.youtube.com/watch?v=PqpfLSqtVgs

Minima Video
The video below is of the Minima SSB/CW transceiver. The transceiver is towards the end of the (rather noisy) video. This is the creator, Ashaar Farhan, in the (Indian?) video.

 

Simple 10m DSB transmitter

From Steven, G7VFY comes news of a very simple 10m DSB transmitter from the blog of KA7OEI. This is an experimental very low power transmitter. It is unlikely to be of use in serious applications, but the range might surprise some.  On 10m, the antenna is efficient and on a clear frequency it has the potential to get a long way. Over 1000km would not surprise me on a totally clear frequency. After all, 1mW (or so) is about 53 if a 100W signal was 59+12dB. On 10m such signals with 100W are very possible.

See http://ka7oei.blogspot.co.uk/2014/10/the-pointless-10-meter-dsb-qrp.html .

Micro-40 DSB build

http://aa7ee.wordpress.com/2013/10/19/the-vk3ye-micro-40-dsb-transceiver/ has a beautiful description of the building of this little transceiver using Me-squares. There is  a complete walk-through of AA7EE's build - truly beautiful workmanship.

10m Simple Sideband (DSB) Transceiver

Regular readers of this blog will recall that about a year ago I started breadboarding a simple DSB speech transceiver for 10m. Having had great success with the WISPY 10m WSPR transceiver, I now have a very simple design for the TX part of such a DSB speech transceiver (just need to add an audio preamp/clipper/filter), so I am beginning to get ideas together for this project again. A power of around 1W pep (DSB) equivalent to 500mW pep SSB is the minimum I think. On RX a single balanced diode mixer (or a double balanced mixer such as an ADE-1 or SBL1) should be fine. For the VFO, I am thinking of a mixer/VFO with a tuning range of 28.4-28.6MHz. The RX audio design from WISPY works well but it will need another audio stage to drive headphones.

I want to have another go at a 136kHz transverter (based on my latest architecture), more non-line-of-sight (NLOS) optical comms, E-field probes, more earth mode comms, WSPR beacons for other bands,  etc etc...

My problem is I've too many ideas in my head and not enough hours in the day to try them all out. What I need is a spare, free, design team (!) to take these ideas forward whilst I get on with other things, like looking after the grandchildren, gardening, maintaining the house, eating and sleeping etc. Since retiring 4 years ago I have no idea why I've no spare time!

QRP 10m WSPR

As I cannot access my "lab" currently (kitchen refit materials are everywhere!) I am restricted to operating from my shack, so this morning I've been trying out 28MHz WSPR with 500mW out to the halo in anticipation of my QRP WSPR transceiver design coming soon. This will be DSB, so I will need 1W RF out to get the equivalent of 500mW on the WSPR frequencies.

500mW 10m WSPR reports today

Not unexpectedly, there are loads of reports on the screen when I last looked from all over Europe. The best report so far today is +8dB S/N which suggests just 500uW would have been sufficient to be spotted. I know that others have achieved similar, indeed very much better, success when the band is open. What is also intriguing are that I have been spotted within the UK at over 300km, presumably by Es or backscatter, although maybe by tropo?

I have still to finish off the 472/500kHz transverter and write this up before starting on the 10m WSPR rig, but should have the latter done quite soon. It will be fun to have a stand-alone 10m WSPR transceiver running with a little netbook.

Sub-harmonic mixer based 10m WSPR transceiver

My favourite HF band is 28MHz and I often put my FT817 on and run WSPR in the background whilst getting on with other things in the shack. You may be surprised how often good DX reports are received. This ties up the FT817 so I have been rethinking how to make a very simple WSPR transceiver for 28.1246MHz.

One neat idea is to use a 14.060MHz crystal (cheap from GQRP) pulled up to 14.0623MHz (it is possible) and use this to drive a Polyakov sub-harmonic mixer, which needs half frequency drive, in a simple direct conversion receiver feeding a PC sound card via an isolating transformer. The same oscillator, doubled would be fed into a single balanced DSB modulator and a small QRP PA stage. The resulting WSPR signal would appear as a DSB signal , not SSB, so half the power would be wasted but who cares with milliwatts?

The resulting full WSPR transceiver would be extremely small and simple, need no VFO or VXO and could be left running almost continuously when the PC is switched on. This would be ideal with a small netbook PC.

The idea is not new: see for example http://www.qsl.net/d/dl1gsj/html/qrssrx30.html .

Sounds like this is my next project......

Ultra-simple WSPR

G3XIZ has been having a lot of success on 40m WSPR recently using a 100mW DSB transmitter to generate a WSPR signal. All that is needed is an audio source (for the baseband WSPR signal), a balanced mixer and a PA. Of course, with this arrangement 3dB of power is lost in the "other" sideband which will appear outside of the WSPR sub-band. At some point - when I've got my lightbeam kit finished in January - I hope to try this arrangement on 28MHz WSPR. A very inexpensive 14.060MHz QRP frequency crystal will double to 28.120-28.130MHz so will be ideal to generate a 28MHz DSB WSPR signal at 28.1246MHz. Of course one could convert the TX into a phasing exciter and null out the other unwanted sideband. This should not be too difficult either as the phasing has only got to be good over just a 200Hz wide audio band, unlike speech which needs good phase balance over the full 300-2.4kHz band.

The Tenbox - name chosen

Thanks for the suggested names for my 10m DSB project. The one that wins is the Tenbox, which is the logical name following on from my earlier AM transceiver projects called the Fredbox (2m) and the Sixbox (6m). The Tenbox is just right - a small box with a complete, yet simple, 10m sideband transceiver inside that should be completed in the next 4-6 weeks.

There will be no progress now for a week as my little 3 year old grandson is here to stay and he sleeps in the shack bedroom. Maybe I will teach him a little more CW.

More work on the 10m DSB rig

Today I continued breadboarding the TX strip of the 10m DSB transceiver changing the single balanced mixer to a broadband design and adding/changing stages in the driver and PA. After the mixer, the driver/PA design now has 2 transistors and 1 FET PA with an output of around 1W pep. This is not enough. My aim remains at least 2W pep either from this line-up (with an IRF510 PA) or with a different PA.

Incidentally, I need a name for this rig. I used the name "Tenner" for my 10m CW transceiver, so what shall I call this one? Please give me some ideas! DSB10? Sidebander10? 10phone?

10m DSB rig progress (some)

Today I spent a little time on the transmit strip of my 10m DSB transceiver project. I started with the single balanced mixer using a T50-6 (yellow) toroid tuned to 10m, with LO injection from a signal generator and LF via a small audio preamp from an audio generator. For now I used a 1kHz tone to ensure drive levels were OK. Output is currently 20mW pep with 2 small 2N3904 linear stages following the mixer. To reach a useful RF level I therefore need another 20-23dB, easily done in two more stages. This would take me to around 2-3W pep.

Simple Sideband QRP 10m transceiver started

A long overdue project of mine is a QRP 10m simple sideband (DSB) transceiver. Having got the 4m transverter working (circuit to follow) I'm now starting work on this project in time for the summer sporadic-E season. A website to track progress on this has been started. See a Simple Sideband 10m Transceiver. With any luck this will be breadboarded by mid-March. I have included lots of links to other 10m designs from which ideas will be (or have already been) gleaned.

Starting work on the 10m transceiver today

The weather's a bit warmer (0 deg C) so I'm going to start on the local oscillator section of my DSB transceiver today. Will almost certainly use a mixer/VFO or mixer/VXO using a ceramic resonator instead of a crystal. This will allow me to cover a useful part of the band on either CW or sideband and to provide CW offset easily. The DSB modulator will be a matched pair of diodes.