WSPR'ing? No, Shouting! AARRRGGHHH!!

Sadly though, its me whos shouting 'AARRRGHH!', not the 10m Wispy! I rigged this up again today, this time with the 9t trifilar toroid fitted. Nothing. Then I noticed one of the diodes was backwards! This sorted out, still nothing.

I can see there is some signal getting out of this beast. The spectrum analyser shows the start of a peak with modulation applied, but its many tens of dB down on the levels measurable from the doubler. This is beginning to drive me bloody mental! I just cannot fathom out why this damn mixer wont work! I isolated it from the following driver stage, just in case a fault there was pulling it down, but still nothing. Yet when I mocked this mixer up on its own, it worked? Why will it not work in circuit?

The only thing I can possibly think is that its a phasing issue, I must have the phasing wrong, but it all looks right to me. Im going to have to ask for help with this again from the G-QRP members.

I know I have started Project TennaLady to be a simplified 2nd version of this circuit, but I hate the idea of abandoning Wispy. There really should be no reason for it not working, and ive pestered Roger G3XBM so often about it, and hes always been very helpful, I do feel a bit like i'd be letting him down if I cant make it work.


On a lighter note, the small amount of other radio done today has been good fun. Most of the day has been taken up with church visits as part of my study of local extant war graves (see my other blog http://selbywargraves.blogspot.co.uk/ if your at all interested), which was intended to be a single church visit but turned into five, followed by a bit of gardening. The bit of gardening led to several hours of cutting and blanching parsnips for the freezer!

What I did manage to do though, was to transfer the PSK-20 onto solar power. I have a small solar panel up on the shack roof, about 6" x 18" and rated in the region of 6W, although it is now rather old and inefficient. This feeds a 12v 7Ahr SLAB. I transferred the power cable of the PSK-20 from the main PSU to the distribution block of this system, and switched on. Odd, both LEDs lit? Ah, take the multimeter measuring the charging current out of circuit! Thats better. With the PSK-20 running on stored solar power, I answered a CQ from IP8AAW, an Italian special event, and worked him on first go.

I should get a bit of work on Wispy done tomorrow morning, but I have to be at work mid-day for a secondment interview, followed by Sams parent/teacher evening, then Karate.

Going 'a shade greener'?

There is a company, located not too far from me, who specialise in photovoltaic installations, and trade under the name 'A Shade Greener' http://ashadegreener.co.uk

I am somewhat curious about this. I have for a long time liked the idea of a solar power installation. In fact, I already have a small solar panel used for charging a 7Ahr SLAB, and using that to run small loads such as my weather satellite receiver, which now is very little used (hmmm, theres a thought - I dont use it because I no longer have the antenna, but I might try it on the discone!)

A shade greeners business model seems good, if a little cheeky. Essentially, what they are offering is a totally free installation. Yes, totally free. So, whats the catch? They say there isnt one, and in many ways thats true. It does seem a pretty risk free plan. Basically, you sign to a 25yr lease. They rent your south facing roofspace for 25yr, during which time, they also maintain the system for free. As the consumer, you get the benefit of the free electricity it generates. All sound too good to be true so far?

Well, ok then, heres the deal. Yes you get free electricity, but only during the time the panels are generating. When the panels are not productive, ie when its nighttime or bad weather/thick cloud, you buy your power from the grid as usual. So the savings you can make depend entirely on how much of the free power you can use, during the day, without going above the generated amount. This is where the company's business plan starts working. Most people are not about during the day when the power is being generated. Also, if they are, its likely that less power is used anyway, as lighting and heating are often not required. So, because the home owner isnt using all the generated power, the company makes its money on the payments from government under the FiTs scheme, which pays for microgeneration to feed into the grid, and it seems pays well.

So, how to get the most from a free installation? Its all down to how much of the free power you can use at the time. The usual technique is to change your habits. Run the dishwasher, hoover, washing machine etc, during the day, and in series, not parallel. Running them all together will go above the generated load and cause you to have to buy from the grid. Using them one after the other can make the most of the available solar power.

So also, running a radio station during the day (reasonably convenient for me) uses free power, unless you go over in the transmission peaks! But what about evening or night operations?

It all comes down then, to storage! I am reasonably lucky in that I can occasionally lay my hands on surplus but still reasonably usable large sealed lead acid batteries, ex of UPS systems. By using the free power from a solar array to charge a bank of large SLABs, that power is then available to run the radio station and any other suitable loads later.

Its unlikely that such a system could be built for a reasonable cost that would run such kit as washing machines, but using a suitable inverter it could run a telly, or perhaps the fridge? Also, my kitchen and bathroom lighting is already 12v LED. By replacing more lighting with LED technologies, battery stored power could be convenient.

I have on order a roll of this stuff

this is flexible LED lighting. 5m long, extendable, and comprising about 300 white LEDs. It can be used by sticking it to a surface, say the underside of a shelf on the radio desk, or on the top of a picture rail. Im going to try this out as a way to replace mains powered lighting in my shack and workshop. I will then look at the use of solar charged batteries for running this.

The company's free system doesnt have many disadvantages, but its not easy for the home owner to actually make much of a saving on their power bill, likewise the lease timeframe is somewhat excessive

A Shade Greener free photovoltaic installation
Pros -
Free Installation
Free maintenance
'Some' free power

Cons -
Savings available to home owner are vastly lower than profit available to company
25yr lease is excessive. 10-15yr would be more acceptable
Array remains company property after lease expiry. Array passing to consumer ownership would be preferable 
No bidirectional energy monitoring. I would want to see what im feeding to grid.
No specs regarding RFI/EMC of installation

That last con is of particular concern. The chargers/inverters etc used would have to be properly filtered, in effect 'silent' at radio frequencies. I would not tolerate ANY increase in noise floor from the system.

Now, I know my roof is suitable, even without them doing a survey (hey, you dont study Environmental Science and Renewable Energy without being able to work these things out). I could buy my own installation, in which case I get all the free power, plus the feed in tarif. But heres the reason this company can do this - I dont have the money for that!

So its something im interested in, and might consider. Of course, by blogging about it, ive effectively given A Shade Greener some free advertising! Perhaps they will read this! If so, then they are welcome to contact me to discuss providing me with a 'showcase' installation, tuned somewhat more towards my requirements. Im sure its unlikely they have an amateur radio station in their installation portfolio, and even more unlikely they have a battery storage and comprehensive LED lighting installation. Maybe they would like to go with my plan as a live demo of what solar can do?

1st QSO with PSK-20

After a while just monitoring this morning, and checking settings (remember to turn that sound card AGC off!) I fired up and answered a CQ. My 3W PSK-31 signal was answered first time by 9A5ZM in Croatia. He reported my IMD at -17dB and S/N of 25dB, solid copy.

So all is well with the rig. It has a 5A fuse in at the moment, which I will change for something more appropriately rated later. But im happy with it and its performance. Im only a little sad that some of the lettering rubbed off during drilling for the mods. I'll find  a nice box to keep it and its cables in, ready for field use.

PSK-20 working, plus Sudden -2 and a voice keyer

Most of today was taken up with Sams karate grading, so it was very late that I was free to play with any projects. Sam passed and is now 8th Kyu, which meant I had to cook his favorite tea - lasagne. With a good meal and a few bevvies in me, I found a few moments to complete the modifications of the PSK-20 transceiver.

The RF sniffer circuit needed to be as small and as close to the antenna connector as possible. So I decided to build it 'ugly' with all the parts having their leads cropped back as far as possible. The 2k2 resistor is soldered directly to the pin of the BNC socket, and the ground connections are straight to the ground-plane of the PCB.

With the mods done and a power cable made up, it was time to add power!. Always a daunting time, she fired up with no obvious signs of distress, and a healthy green power LED. I had calculated the current limit resistor for the power LED based on a 13.8v supply, which came out as 1k2, so I bumped that up to 1k5 to give a bit of leeway.  I then connected the audio out to the USB sound-card on the laptop. Hmm, nothing? Ah, plug it into the microphone port! Despite it being late evening, several PSK signals began to scroll down the FLDIGI waterfall.

Whilst connecting the antenna patch lead from the rig to the ATU, I had to move a few half finished projects out of the way. One is a Kanga Kits Sudden-2 receiver. This is effectively 'finished' apart from a case and knobs,

but it has provision on-board for an audio filter. After contacting Kanga, I now have the schematic of the filter, and as its pretty simple im sure I have the parts somewhere already, so I intend fitting that before boxing the project up. I already have a large plastic box for this, selected with the intention of it having an internal battery.

Also knocking about on the desk was this little digital voice recorder that cost me about two quid from Hong Kong a good few months back

 This was supposed to have been wired up to the headset system of my mobile installation, so I could call CQ whilst driving and not worry about my throat drying out! But when the rig went faulty this got forgotten about. I really ought to get it finished!

Ive run the PSK-20 now into test load, and also a quick test burst to air. No QSOs as yet, as I want to check the levels etc first and make sure every things aligned properly. In idle mode, with full audio drive the power meter was reading a good steady 3W. As idle mode is a 50% duty cycle, I need to back the audio drive off to a point where an actual data transmission gives 3W, which I think means idle should be about 2W. I'll sort that tomorrow and give it its first real run out on air.

The rather out of focus picture above shows the PSK-20 on receive, with the power LED lit. On Tx, the red LED below is driven by the RF sniffer and lights brightly, flickering slightly with data modulation. I will put the case back on tomorrow. My only concern is that the PA heat sink does get bloody hot. Perhaps the addition of a small cooling fan could be useful here.

Adding a Tx/modulation indicator to PSK-20

The older version of PSK-20 was somewhat different to mine. For a start, it had a 9-pin D socket to allow control of the PTT by a computers RS232 serial port (RS232 was mentioned in a recent training course at work, and I, rather embarrassingly, was able to real the protocol specs off!). The newer version like mine has 'tone controlled PTT', meaning that the rig detects a control tone on the sound card right channel to control the transmitter, eliminating the need for a serial port, and making connecting up one less cable.

Something however that the older version had, which the newer one doesnt, is a Tx/modulation indicator LED. Now, although the computer will say when its in transmit mode, I rather like having a hardware confirmation! So as previously mentioned I will be adding this Tx LED. The additional circuitry is very simple and will easily fit on the underside of the PCB

The schematic above is the recommended circuit taken from the old PSK-20 manual. Its not a great diagram, as I recreated it in MS Paint, which is frankly rubbish, but it gets across just how easy this mod is.

This will need building as close as possible to the antenna connection. Luckily, the antenna socket is an insulated PCB connecting but panel mounting BNC, which means it has easily accessible pins. The simple RF sampling circuit will fit directly to the antenna connections, I might even be able to build it from SMT parts for the absolute minimum of adverse insertion effects. I dont really know why they didnt keep this circuit in the kit in the newer versions.

Heres what the manual has to say about this circuit under 'Transmitter Operational Adjustment -

If no wattmeter:
Install a T1-3/4 LED at TP2. The 'flat' edge of the
LED body should face to the left. When transmitting,
this diode should glow steadily when idling and will
flicker noticeably brighter when you're typing. Adjust
the master volume slider as needed to achieve this
indication. Note that this diode may be installed
remotely on a front panel to serve as a rough power
indication.

Im not exactly sure what a T1-3/4 LED is, but I suspect its a common or garden 5mm LED!

UPDATE - Ive just looked this up and it seems T1-3/4 is just the package style for a typical 5mm LED. So thats that sorted. Im off to bed now as its Sams karate grading in the morning and ive already had three glasses of wine...

DC Power input mod on SWL's PSK-20

 I have mentioned the Small Wonder Labs PSK-20 a few times, and it occurred to me earlier today that I really ought to explain these things a bit more when I mention them, before going on and on about what im doing to them!

Well, the PSK-20 is a small single conversion superhet transceiver from Small Wonder Labs. It is fixed tuned to the digital sub-band on 14MHz for operation of BPSK (binary phase shift keying) mode transmissions. Its a very simple rig in terms of use, you simply connect a 12v power supply, a 50 ohm antenna, and a pair of audio cables from and to a PC sound card. Then, running suitable datamode software such as FLDIGI, HRD, MultiPSK etc etc, this simple set should give about 2W of output, ample for plenty of fun making PSK contacts on 20m. It was supplied as a kit, but sadly by the time I wanted one the owner of the company had retired, and they were no longer available, so I bought mine from someone else, meaning I didnt have the fun of building it.

My only concern with the  transceiver was the lack of any protection on the power input. DC at 12v is fed via a DC barrel connector to the unit, via only a series diode. This means, apart from the Vcc being 0.6v lower than the incoming supply due to the drop across the diode, that the only protection is against reverse polarity. I doubt however, that the diode would really hold up in that situation for very long!

The unit is relatively simple, and so I was more worried about a  fault in the transceiver knackering an expensive power supply! Or, and probably of greater real concern, of causing a huge current draw and melting the power cable, a definite fire risk. As someone who has but one level of OCD, which is an obsession with fire extinguishers, this is what needed sorting.

The solution was, obviously, to fit a fuse holder! This needed a surprising amount of thought, as not only must it be in keeping with the layout of the rest of the rear panel, but I also had to consider the depth of the devices penetration into the housing. Too deep, or in the wrong place, and I run the risk of damage to the transceiver components. The photo shows the new fuse holder fitted in place. This holder had a little locating stud, so as well as drilling a 12mm hole, I had to file a little extra cutout for the locating stud. A small piece of heat shrink tubing covers the end terminal as further assurance against any contact with the board components.

As the PSK-20 has no power switch, I decided to add one at the same time. The connection to the fuse holder for the incoming power comes from the reverse polarity protection diode. The cathode leg of this was cut and the wire removed, the holder and switch then being wired in series.

The two other issues with the transceiver design were the lack of any indications of when the unit is powered, and when it is transmitting. To solve this, a pair of 5mm LEDs have been fitted onto the front panel

 

Keeping things simple, ive gone for red and green. The green LED will be the power indicator, and will be lit whenever the rig is switched on. The red LED will indicate Tx, and is a bit more complex! The drive for this will come from the addition of an RF power sniffer circuit, which will sense the RF power at the output of the LPF, just prior to the antenna connector. Its a simple diode detector circuit. The addition of this will also act as a rudimentary VSWR indicator, although im likely still to make use of a proper VSWR bridge in line with the antenna.

 

This is the whole thing back in its case, but without the lid. I was a bit concerned about the LEDs being too close, but there is in fact plenty of space. The LEDs need their current limiting resistors fitting, and then wiring up to the board. Im almost ready to try this on air, but I also have the power cable to make up before that. The audio cables have been tested. That reminds me, I need to organise a container to keep audio patch leads in! Ive got one now for USB cables, that sits under the PC desk, so all those cables are now tidy!

Small Wonder Labs PSK-20

The two 3.5mm jack leads have arrived, so I can now set up to try out the Small Wonder Labs PSK-20 14MHz PSK Transceiver. Ive waited this long to save dwindling down my meager stock of jack plugs!

Ive metered out the DC plug and socket, and all looks good there. However, Im not happy about directly connecting this little beauty to my PSU, which is capable to over 20A, so intend making a small modification tomorrow and fitting a fuseholder to the connector panel of the unit.

 So the cabinet has been dismantled to remove the panel ready for marking and drilling. Theres plenty of space to install a fuse holder on the connector panel. The 'front' panel itself is completely blank.

The SWL PSK-20 is internally a handsome bit of kit, sadly now out of production. All being well, I will have it on air tomorrow evening. I still need to give the soldering a visual inspection, just in case, as it were, although ive no cause to think there are any likely problems

Ive also ordered another DVB-T dongle, identical to the other I have on order. This is because I have an idea or two regarding doppler RDF, but might try a few other ideas out as well. If nothing else, the two mini-magmounts i'll end up with im hoping to modify to complete my TDOA (Time Difference Of Arrival) direction finder. This will just be a few PIN diodes and resistors.

No more from me for now. Ive been awake since 16:00 yesterday, first to do a night shift, but then I hung about and joined my colleague Dave Preston and four of the Field Support Team girls, for a visit to ITV studios and the set of the long standing soap Emmerdale

The photo above is on the set of the world famous Woolpack Inn, with myself in the role of customer. And yes, it is real beer! These sets are at ITVs Kirkstall Road studios in Leeds, where we also had a smashing dinner of fish and chips in the canteen, before visiting the 'external' sets, which comprise a custom built entire village, carefully built well away from prying eyes in the Yorkshire countryside.

So im now rather tired, and am going to bed.

The slow boat comes in!

I didnt get much radio done at all today, instead I decided to get some sleep in advance of night-shifts. I did, however, set up for 10% WSPR beaconing on 6m. The result of which, I found when I woke up, was a grand total of no spots whatsoever! Oh well, i'll stick to HF for WSPR until the conditions improve.

Several more items arrived today from China. These included the 10x 10k potentiometers and 5x SPST toggle switches, both packs cost less, including shipping, than just one item would have cost from a UK seller! I do try and support British business, but its a no brainer to me to buy parts for experimental purposes where I can get them at the best value. I'll support British business by buying local veg, meat and cheese, and      local beer (oh, and whilst there still in the UK - Scottish single malts!), or for components, from sources such as rallies, and club sales.

Also today came the 'windows 7 compatible' USB micro Bluetooth dongle. This cost a whopping 99 new pence, so I really wasnt holding out much hope. But Windows 7 saw and installed it no problem. So far so good then, I then tried to use it. It was at first a bit flakey, but then settled down. Bluetooth is very easy to use, once you know how, and it took me a while to work out what to set on both the PC and the external device (in this case my mobile phone) to be able to transfer files, but that learning curve mounted and a few files were successfully transferred each way. So, for less than a quid, im fairly happy with that. It should help Julie transfer pictures from her phone to the PC.

I'm still waiting on the 100k potentiometers, the audio jack cables and the SDR DVB-T receiver dongle. Hopefully these will arrive soon.

The mixer balun/doubler tuned circuit core for Wispy has been rewound as a 9t trifilar winding, and is ready to be re-installed. I feel somehow happier with this than with Rogers original 9+2+2 toroid, as I know all the turns are in the right place. Ive already swapped the 1N34s for 1N4148s, and will see just what the output is like. I have  a feeling something is amiss with the driver amp following the modulator, which might be why im not getting much output. I'll also improve the LPF with a 7-pole version.

All this will probably have to wait until saturday. Although I will be off shift by friday morning, im on a visit to Yorkshire Television and the Emmerdale studios, so im likely to be rather knackered after!

Possible 50MHz WSPR operation tomorrow

Ive decided to re-jig the station for more control over my 6m activity, with the idea of potentially putting WSPR on 6m tomorrow.

The big problem with 6m is lack of antenna monitoring. (gawd im starting to talk like at work!) so I have moved the Diamond SWR bridge out of the antenna feed line from my 2m station up to the halo, and will patch this into the 6m beam feeder line tomorrow morning when im back from hospital. I will be able to accurately set the Tx power on 50MHz then, although running to test load will still be a manual patch.

This will leave the 2m antenna unmonitored and the 2m station unprotected, but its not often used at the moment, so I can always put the Bird 43 in line if needed.

Now the storms are behind us, hopefully i'll get a spot or two on 6m!

Waiting for the slow boat from China

Several projects have effectively ground to a halt at the moment, as Im awaiting the delivery of a number of parts, the majority of which are on the slow boat from China, or, at the very least, on the low priority air mail from Hong Kong!

One that has arrived is the 1mA panel meter, but the swift delivery of that probably has more to do with the depot its come from being in Swindon! The wait for parts has delayed my live testing of the Small Wonder Labs PSK-20, as the necessary audio cables are on the shipment from the Far East, this being because at 99p each I simply cant make them myself for that price!

Little has been done radio wise other than the sound-card mod these last couple of days, and little will be done over the next either. Yesterday I sacrificed time in the workshop for a boys day with my eldest son Sam, and enjoyed the Lego Movie in 4D followed by pizza! Today I have been 'dataminer'ed' to death, and indoctrinated into the dark arts of 'site manager' at work. Tomorrow, after another hospital appointment, I may get a bit more done on one project or another, before I have to go to work and keep the UKs wonderfully educational television working for another night. On the plus side - tomorrow night is company sponsored pizza night!