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.

 

More on the Minima transceiver

My mention of this Ashaar Farhen design yesterday seems to have been very popular, so I have dug out a bit more information. As it stands it produces 1W pep but it is easy to add a further PA.

See http://www.sarfata.org/ham/minima/ .

Although a kit of parts is available, I am not aware of a full kit with enclosure and a PCB being available as is the case with the BitX from Hendricks Kits.

The Minima transceiver

See http://www.phonestack.com/farhan/minima.html

This is the latest project from Ashaar Farhan. Component cost is said to be less than $100. This is based around a Si570 sythesiser and a programmed Arduino micro-controller IC. It looks a simple to duplicate rig covering up to 30MHz. It is the successor to the BITX rig I think. The IF is 20MHz. If you only want 0-15MHz or 15-30MHz (i.e. not both) the rig get even simpler.

Unbelievable prices!

See http://www.banggood.com/T-688-0_5W-UHF-Auto-Channels-Mini-Radios-Walkie-Talkie-Pair-Black-p-920432.html .

I cannot believe these prices. £13.91 for a pair covering 400-470MHz, 500mW, with free shipping to the UK. That is under £7 each for a 70cm transceiver from Bang good.  Just how do they make any profit? Buy 3 sets and it is even cheaper.  Quite remarkable!

The link says T688 but the photo T668. Not sure which is the correct number but the link works.

The rigs run from 3 x AAA batteries (each) and the price does not include a charger.

Para-saki all diode QRP transceiver

This looks like a design by Michael Rainey AA1TJ, but this one was on a German blog site of Peter DL3PB. I was very annoyed by the Facebook pop-up that kept appearing. I kept closing the pop-up but it is really annoying. Website owner - PLEASE get rid of it!

See http://streampowers.blogspot.co.uk/2013/08/para-saki-qrp-transceiver-fact-diodes.html .

The design makes extensive use of tunnel diodes, a Michael Rainey favourite.

FT991 multi-mode, 160m-70cm all mode transceiver

The first UK price looks like around £999 from Nevada who expect stocks spring/summer 2015. This is more than I was expecting.

This image is the best I could find. The image is located on the Universal Radio site in Ohio and the link to the image will be removed if this is a problem.

http://www.universal-radio.com/catalog/hamhf/3991lrg.jpg

Click the image for a bigger, clearer picture. 

I would consider investing in this transceiver, but would be looking for a better price. The FT450D is currently £699 in the UK (even less at MLS £619.95 according to G1KQH) I wonder if they will spin out an FT817 replacement based on the FT991 design? I am sure there would be a good market for a 5-10W version here in the UK.

X108 20W transceiver

G1KQH informs me this Chinese transceiver is available for an introductory prce of £399.99. Personally I think this is MORE than I would expect. To me it still looks like a "back shed" design. I notice this supplier has sold out.

See http://www.sinotel.co.uk/index.php?main_page=product_info&cPath=20&products_id=183&zenid=oi6qsdgfla6p73q0c5vhs40kj3 .

This is an introductory price for the basic version without TCXO and noise blanker. The FT817ND is now available for well below £500 with cash back offers and, to my mind, is a well proven MF-UHF design.

The X108 claims " minimalist industrial design". Read NO industrial design in my book! Still waiting for the Chinese "killer" radio to out-smart the Japanese. This, in my opinion, is not it.

Chinese X108 QRP transceiver can now be ordered

G1KQH has told me that the 9-band multmode transceiver, the X108 from China, can now be ordered on-line.

http://www.wouxun.us/item.php?item_id=346&category_id=65

Personally, I'd prefer the FT817 but, even with shipping to the UK, taxes and duty , the price is attractive, even if the product looks rather ugly (to me). It still looks "back shed" design to me. Personally I'd rather wait until the Chinese are really there with their designs. Others may disagree, but the industrial design of this product certainly lets it down.

Also, this is a kit, but with very little soldering.

mcHF transceiver

Graham G8NWC has brought this QRP transceiver (the mcHF) to my attention.

See http://www.m0nka.co.uk/ .  It is described as a small and inexpensive homebrew HF transceiver.  Features (as listed on Chris M0NKA's website):

• Standalone and compact embedded transceiver
• Operates on USB, LSB, AM and CW
• Large 2.8 inch color LCD
• Four encoders and 17 buttons for easier operation
• Fast and fully electronic RX/TX switching
• Two USB ports – for PC control and external keyboard
• Two temperature compensated oscillators/clocks makes it ideal for digital modes
• Four digital filters – 1.8kHz, 2.6kHz, 3.6kHz and 10kHz
• Built in Iambic Keyer that supports Mode A and Mode B
• Large 48kHz spectrum display

QRP rigs

See http://www.vanyi.net/homemade/homebrew-hf-ssb-transceivers/ .

This page has a nice collection of links to a range of (mainly) homebrew QRP transceivers for various bands. Well worth a visit and good browse.

LNR FX-4 transceiver?

https://scontent-a-lhr.xx.fbcdn.net/hphotos-frc3/t1.0-9/1278189_519456928132890_1956196588_n.jpg

See http://www.lnrprecision.com/ and scroll down the page.

This looks "Chinese" in origin and I am wondering if this is a badged product?  It looks a bit like a poor man's KX3. It is a 4 band, 5W QRP CW/SSB transceiver.  In the USA it retails for $450. It is clearly aimed at backpackers.

See https://www.facebook.com/media/set/?set=a.519456908132892.1073741827.229134337165152&type=3 for some images of the little rig.

PY2OHH's Pititico 10 parts transceiver for 40m

Andy Cutland has sent me this link. It is from, Miguel,  PY2OHH's excellent site which is full of ideas for QRP and QRPp enthusiasts. I can thoroughly recommend it for ideas.  I would expect this RX to hear signals, but be quite deaf as there is no audio gain apart from that in Q1.

Apparently the headphones were around 500 ohms impedance. I guess a crystal earpiece might work as audio is derived across R2. Maybe then C5 could be deleted?

Q1 must act as a (crystal controlled) regenerative detector on RX with the level of oscillation set by R2. Not sure of RX-TX shift as this will depend on RX and TX current. There is no low pass filter either, as shown. This means harmonics will also be detected and emitted. Still, this is meant to be VERY simple. I must try it.

http://4.bp.blogspot.com/-TlNqb0N-7V0/U0SFVljBTjI/AAAAAAAAUkY/xbyhirCu7AU/s1600/pititico.gif

President Lincoln II prices

Today I emailed Nevada to see what their best cash price is for a delivered President Lincoln II 10m transceiver. I have seen it for £234.95 on eBay, but this is with just  a 12 month warranty. I did not ring Nevada because of my breathlessness due to the stroke after-effects. As yet, they have not responded. Other people have recommended the (less expensive) Anytone series which are available under a range of brand names for around £149.

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.

G4HJW "Finningley" Optical Transceiver kit

The G4HJW optical transceiver kit

Bernie G4HJW is well known for his innovative work on microwaves and optical comms. Last year he designed a neat, part SMA, optical transceiver kit to build at the Finningley round table meeting. The transceiver is capable of very good results and several (around 70) have been built and used very successfully. I believe the best DX QSOs at 481THz have been over 60km using these in 100mm optics.

Exactly when I'll get my kit built I'm not sure but it will be good to have one of these available for optical line-of-sight tests in the autumn. Once assembled, I shall be looking for some 2-way optical QSOs beyond the 10km speech contact I achieved with my own kit last summer. In East Anglia, the issue is finding some hills to allow long line-of-sight paths.

Bernie is, I understand, considering putting together a further batch of these kits, which make a good introduction to nanowave communications. In addition to these electrical kits, all that is needed is a microphone, headset and some simple optics than can be built for a few pounds.

See http://www.earf.co.uk/nanotrx.htm for more details

28MHz BitX SSB transceiver

http://www.qrpkits.com/images/bitx20acase1.jpg

The very popular BitX SSB transceiver is, to my knowledge, available in kit form (from QRP kits) for both 20 and 17m, but I haven't seen versions for other HF bands.

What would be really nice would be a version for the 10m band where 6-8W would be enough to work the world when the band is open. The IRF510s would need to be changed to a Mitsubishi power FET such as the RD16HHF1.

Does anyone know if a 10m BITX has been done or if a kit is available for this band?

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......