Monday, 31 October 2016

Ultimate 3S - It Lives!

In between boxing up parcels, and scaring kids with my S10 respirator (in my defense it is Halloween!) ive had chance to power up and configure, partially, my Ultimate 3S beacon -

I had a few difficulties at first, due to a crocodile with a wide mouth! It turned out that the crocodile clip I was trying to use had been over stretched and its teeth didnt quite come together, so my -ve lead kept falling out!

It took some time for me to become familiar with the menus and the setting process. I managed to eventually get my callsign and locator set, and a WSPR mode transmission set up. I then had to go Trick or Treating with Tom,

These are the pumpkins I carved yesterday, suffering intense cramp in my hand as a result!

Back in the workshop, timing was set reasonably successfully using my watch. The power output was a doddle to set though, although my QRP power meter and dummy load isnt calibrated! I used my Alinco 2m handheld to calibrate it roughly, by measuring the handheld output on the Marconi 2955, and then seeing what that power read on the QRP meter. With the one BS170 MOSFET, it seems I am getting a comfortable 1/4W, or there abouts. Frequency was more awkward. For a start, I wasnt at all sure what to set! Luckily I discovered the table of sub-bands in the manual, and was able to set up for the center of the band. Then I managed to eventually find my signal on my main radio, which is acting as test receiver.

I eventually worked out, after a few false starts getting great decodes of my own spurii, that I was about 4kHz off frequency. Without the GPS module in use, I had to do a manual calibration. The instructions for this turned out to be in the assembly manual, not the operating manual!

My frequency is now roughly in the middle of the operating window. My own decodes are a bit intermittent at present which im putting down to having set the synthesiser to turn off between transmissions, which I think is causing a bit of a chirp! The 'park' control in the firmware is for telling the synth what to do between active transmissions, so I will set that back to an 'on' state.

The above screenshot shows my WSPR signal, and the recent decodes.

Before I can put the beacon to air though, I need to build a 5V regulator board for it, to allow me to run it from a 12V supply. This is a task for tomorrow.

Box Disappointment

Slightly put out today I'm afraid. Ive finally come today to testing the CRS L/R box I got as part of my order around a month ago from PTS. Unfortunately, theres a problem. The headset audio 'motorboats' and the control functions dont operate. Ive tested it with alternative cables to ensure it wasnt a wiring issue; on two different radios (different types, a 320 and a 350); and with different audio kit.

This is a real disappointment, but not a disaster. Ive emailed Graham at PTS about it, mainly to see if he can direct me to the necessary EMER in order to fault find and hopefully repair the unit. Ive also opened it up to check for any obvious issues, which gave me a bit of a shock as I wasnt expecting it to be anything like as complex as it is!

It is indeed beautifully made, but daunting! I really dont fancy taking it on without a schematic!

On the positive side though today, ive sold on quite a few of my excess PRC-349 batteries, and also the remaining excess PRC-349s! This has effectively covered my original costs, and raised me sufficient funds to progress a few other radio projects.

My list of projects that need completing though is still looooong! Ive made a start of restoring the Clansman hand generator, but thats just a bit of a lick of paint. My next two priority tasks are to test the Ultimate 3S beacon, and to complete the refurb of the PF8, now that I have the capacitors.

The various small modules are beginning to trickle in from the Far East now. The Arduino Mega has arrived, so Im in a position now to be able to start working out the control system for the PRC-320 Remote project. Im short of just the display module for the camera dew heater, with any luck that will come in the next week or so, so that should be finished and ready for the winters night photography.

Friday, 28 October 2016

WhiSPeRs in the night

Ive decided, as of 23:10 UTC, to run my 7MHz WSPR station at 15% Tx and 27dBm (thats 500mW) overnight, and see just where I hear and where hears me,

This is around about the sort of power i'll be setting the U3S up to run when its complete.

Thursday, 27 October 2016

Rishworth UKBB RF Probe made permanent

Despite its simplicity, and that it was intended as a very quick to build, 'no-solder' project, I was so impressed by the neat little RF Probe kit supplied by Rex W1REX or QRPme for the G-QRP club Rishworth Conventions 'UKs Biggest Buildathon, that I decided to actually solder it!

I didnt want to tag solder to the IC socket, as I felt this would look untidy. So I took the drastic decision to remove the socket. Rather than struggle to desolder so many pins, I did this (may Rex forgive me!) destructively - by cutting away the body of the socket and then using a heat gun to melt the solder and allow me to knock out the pins.

The result is now a very neat permanent rebuild, which will eventually get a nice little round housing, a sharp probe, and some nice leads with 4mm plugs on them

I retained the original vertically mounted zero-ohm links, rather than replace these with wire links, so I can still use it as is, before it gets boxed up.

Release the Hydra!

It should be the Kraken, of course, but ive never found mythical sea monsters to be particularly useful in bulk charging batteries!

The Hydra in this case is a simple multi-headed trickle charging solution! Ive found that many deeply discharged batteries will recover, but the Accucel-8 cannot detect them! So, by sticking them on a 15v supply with a suitable series resistor, in this case 120 ohm, I can bring them back up to around 11-13v terminal voltage, and the charger will then detect them and go into the recovery cycle.

The 'Hydra' trickle charger!

With quite a lot to get through, I set up the 'Hydra' to allow me to bring up half a dozen or so batteries in one go.

Ive now run around a dozen through a pair of full Discharge/Charge cycles, and they all seem to have come up to sensible capacity. Around another 50 have passed basic on-load voltmeter testing and should recover when given the cycle charging. About a dozen have failed completely to recover at all

I can now at least dispose of all the known failures, and concentrate on those that show promise. As such, I am also now in a position to separate the 600mAh packs from the bulk of the 550mAh packs! I want to retain around ten good packs for my own use. All the rest can be sold on. Two lots of untested packs have been sold, thats 20 batteries. Im slowly clearing the space in the workshop!

Very kindly, one of the BVWS forum members, Tony, has sent me some 5p6 ceramic capacitors of the type I need to complete the PF8 refurbishment.

I shall get on to that shortly. It now requires some serious dismantling to change these capacitors, due to them being very close to the chassis edge.

The Ultimate 3S is coming along, slowly. Ive not yet heard from Hans regarding the missing inductor, but theres no rush. Ive completed the 10m LPF, this time without getting my wires crossed!

28MHz LPF, L1 (10t) fitted
28MHz LPF L1 and L3 installed and glued down
28MHz LPF complete
Ive also made up the RF coax connection header. This is using my TNC pigtail at present but will do for testing. I dont wish to power the unit for testing until I can have the output fed to a dummy load

RF coax header connection
Ive been hearing a lot recently about 'Parrot Repeaters', otherwise known as a Simplex Repeater, a type of Voice Store And Forward system. These are used on 70MHz where there is insufficient bandwidth for duplex repeaters, and generally seem to be much simpler to build. Im wondering if there is any such machine im my area, and if not, what the requirements would be for me to instigate one...

Tuesday, 25 October 2016

Chance of Aurora and no visibility

Past few nights have had lovely clear, starry skies, tonight theres a class G3 geomagnetic storm

and its bloody overcast again!

There seems to be a correlation between likelyhood of visible Aurora, and how bloody cloudy it is in the UK!

Ive done a slight bit of work on the Ultimate 3S today, such as making up the power cable and the cable to link the GPS module. Ive also ordered a BNC panel socket with coax pigtail in order to make the RF connection. The pads to connect are too small to safely solder coax to, even the very thin stuff I have, so ive added another pair of header pins. I can either solder direct to them, or put a plug on the coax. It will probably be a couple of weeks before the cable arrives, but in the meantime I can test using the only other coax pigtail I have that will fit, which is currently attached to the prototype Wispy project that I couldnt get to work for me. The reason im not just using this on the U3S is that the coax connector on it is a TNC!

I also need to find a suitable case for it! The U3S itself needs a metal box, ideally one that I can modify to accommodate the battery housing from a PRC-349, but then a plastic box will need to be attached onto the metal one to house the GPS unit. The plan being to make the whole thing completely portable - just attach antenna and switch on!

Ive just returned to 40m WSPR - as expected, the geomagnetic storm has pretty much wiped out HF propagation, but, there are a few spots to be had!

Monday, 24 October 2016

PRC-349 batteries for Ultimate 3S?

A thought has occurred to me - Whatever case I decide to build the Ultimate 3S beacon into, could I possibly modify it to include a housing the same as on the PRC-349, perhaps by actually sacrificing one of the '349 cases, so that the Ultimate 3S, once boxed, will take a PRC-349 battery as its power supply?

This would be a very convenient way of powering it in the field, and give me something to use some of these batteries in!

Ultimate 3S Beacon - Almost Complete

As well as charging batteries, and reading more Mark Twain, ive also done a little more work on the Ultimate 3S today,

Having built the main unit, the synthesiser, and most of the GPS unit, I pondered slowly along today with the Low Pass Filters. One small thing I noticed, which I may mention to Hans for a possible future improvement, is that there is no easy way to see what band a filter is built for! The underside of the PCB is all groundplane, and so I have marked the band on mine using a Sharpie pen, but from the component side theres no place to mark. Im not sure what the solution would be, perhaps an extra 1 or 2mm along the side of the board to give a writing space? or perhaps scratch boxes on the silkscreen for each band to mark?

Anyway, the first job way to fit the capacitors. These filters use a tried and tested design detailed on the G-QRP club website and in SPRAT, being 7-pole filters.

Some way of holding the tiny PCB steady is essential! Below is the 10m LPF having its capacitors soldered in place.

One problem with this build, which is fully appreciated and warned about by Hans in the paperwork, is getting the header pins aligned properly! My solution to this problem is to slip the pins into a piece of Veroboard prior to soldering

A bit of Veroboard helps align the header pins when soldering
After this came the task of winding the toroids. L2, the middle one, went just fine, 24 turns. But somehow the other two I managed to get the wrong 'handedness' to them - meaning the wires were on the wrong side of the toroid from the holes! Both had to be unwound and done again! And then, on one of them, I managed to get the turns crossed over and knotted!

But, after unwinding as far as the crossed section and rewinding, followed by some hard work getting the damn thing soldered back in, I finally have the 40m filter complete. A bit of hot-melt glue was used to secure the toroids in place.

The above photo shows my 'almost' complete Ultimate 3S Beacon, ready for 40m operation. The last task will be to make up a header plug to connect power, and to connect the RF out to a coax socket. I should have a coax tailed socket of some sort that will work for this. Another header cable, this time 4-way ribbon, will be made up to connect the GPS unit.

Clansman Battery Not Charging? Try This...

When I was refurbishing my first PRC-350, I had a small problem, in that no matter what I did I just couldnt get any power from the battery cassette. Eventually, after a lot of head scratching, I discovered that something was causing a very bad voltage drop when on load. This was eventually found to be due to corrosion building up under the battery contacts. Removing them, cleaning them up, and in this case replacing a rusty washer, sorted the problem out.

Fast forward to today, and I am somewhat lumbered with a great stack of old PRC-349 batteries. I cant shift these, because no one wants to buy untested and potentially no use batteries, even when offered at under 50p a go!

So, ive started cycling them all to find which are usable. The first problem I had was making a reliable contact to the batteries, croc clips have a tendency to spring off! Here one of the spare PRC-349 chassis came in handy. Stripped of all other parts and connectors, save the battery terminals, this can be easily connected to the charger by, at present croc clips, but soon by its own dedicated pair of 4mm plugs. The battery then screws in and makes perfect contact just as if being fitted for use in a radio.

Chassis turned into charge adapter
One problem that ive been having though, is that some batteries that are showing decent terminal voltage when tested with a meter, fail when attached to the charger. The Accucel-8 reports 'connection break', suggesting that it thinks the battery isnt connected.

After a bit of thought, I realised that in order to check the presence of a battery, the charger must sense current flow to or from it. Now, as for the PRC-350 battery cassette mentioned above, if the terminals are dirty, perhaps the resulting volts drop over the added resistance is causing the problem?

So I took one of the batteries that this morning reported 'connection break', and cleaned the outer surface of the terminals. One connecting to the charger it still reported a fault. So, not just the mating surfaces! So, I removed the terminals

and cleaned away any corrosion and dirt on the fixed terminals of the battery casing, and the underside of the spring terminals

A very crudded up terminal
This time, when connecting to the charger, the battery was detected! It is now on the second of a pair of Discharge/Charge cycles, and so far showing every sign of being a good usable battery!

Sunday, 23 October 2016

Building the Ultimate 3S

Following on from the build of the Synth module yesterday, today ive done the majority of the construction of the QLG-1 GPS receiver module, and the Ultimate 3S Beacon transmitter itself,

First however, I had the faulty Clansman 10m Audio Extension to repair!

This was an absolute pig! The cores are tinsel wire, which gives the cable great flexibility, but makes repair really difficult. In order to rejoin the cores,I had to wire wrap them with solid tinned copper wire, but the size of the cable and the flexibility made it extremely hard to hold everything together while I did this, and then to solder it all together and sleeve the joins. But it is now repaired and tested as usable.

So, onto the Ultimate 3S. Building the QLG1 GPS module is remarkably simple, with very few leaded components to install. Unfortunately, my kit had two components missing. One, a 100nF dipped ceramic, I simply replaced with one from my own stock. But the other missing part is a 0.1uH axial inductor. I havent anything of this value nor even close to it. So ive had to drop the supplier a line asking for a replacement.

As the GPS module is not yet complete, I have deliberately not yet fitted the backup battery. It is just waiting on the inductor now and can then be powered and tested.

Building the 3S itself is a little more complex, as there are more parts to fit, and a higher density on the board, but still quite straightforward. The only thing that complicates it a bit is that the manual covers the controller build for three different projects, which leaves the builder to fathom out which links etc must be installed. I would have preferred the manual to have been more specific to the 3S build. But then again, theres still plenty of optional features in the 3S build to decide, such as whether to have software controlled LCD brightness (in my case yes), whether to soften the contrast control (yes), etc

The module can use its 5v supply to power the BS170 MOSFET PA stage, by adding a link, or the PA can be powered by a higher supply, for instance if fitting extra BS170s, without the link. As I want to use mine with the one installed transistor first and then add more later, and didnt fancy having to unsolder a wire link, ive been clever and fitted header pins and a removable link as used on PC motherboards. Ive also done this for the two links that hard wire the LPF module connections, as these links need to be removed if the relay switched band module is used, which I may wish to add later,

Im hoping alls well, but I wont be powering it up just yet. Im going to build one of the LPF modules first, so its all ready to test fully.

G-QRP Club Rishworth Convention

Today was the G-QRP club convention, an event which ive looked forward to all year, and that sadly has come to an end, this being the last one. For this, I managed to assign myself a healthy budget, far more than I can normally have for a rally, and set off very early, intending to make a good day of it. I even lugged a ton of PRC-349 batteries there with me to go on the bring and buy stall!

And what a great day it was! Three thoroughly enjoyable talks, cheap cups of tea and biscuits, a fun Buildathon, and lots of interesting junk!

Buildathon kit provided by QRPme

The Buildathon project was a novel no-solder RF probe kit. Over 100 of these were constructed, mine taking me around 2mins. W1REX of QRPme was the provider of these, and of the very enjoyable talk that went with them! Its actually such a nice little kit, and practical too, that im going to remove the SIL sockets and make mine up permanently. Ive got a couple of small analogue multimeters on order, I might sacrifice the available ranges on one to build the RF probe kit in with it!

I only managed to find one of the capacitors I require for the Pye PF8, the 18pF, and I found it in a £1 bag of random parts! Once home, it took me the best part of two hours to sort the bag out and pack all the bits away!

Some of the contents of a £1 goody bag
 My main purchase though was, as intended, the Ultimate 3S kit from QRP Labs. I opted for the additional GPS kit and an extra Low Pass Filter kit. Once complete I will have the option of 40m or 10m operation. I also got the extra BS170 MOSFETs to ramp the output power up a little.

I have already completed construction of the Si5351A Synthesiser module.

Si5351A Synth module from QRP Labs
I also paid up my G-QRP club subs whilst there, and picked up a few non-electronic items, a copy of the ARRL Handbook for Bob, so he might finally stop nagging me about things and leave us free to discuss VHF rhombics more, an old IBA engineers pocket book for 20p, and another mechanical calculator disk for my collection. I also somehow missed Mike Walker who visited but briefly. And, sadly, I also came away with all the batteries I had taken!

Ive made a start then on testing the remaining batteries. Ive taken one of the spare PRC-349 cases to make a battery charging dock for use with the Accucel-8. Perhaps if I do test them and find only the ones that hold a decent charge, i'll manage to sell a few! Ive also made a start baring back the cores of the damaged audio extension cable to repair it, this will be no easy job, as the damn wire is Litz! some very fine wire winding work might be needed.

Wednesday, 19 October 2016

Further Restoration of the Pye PF8

With G-QRP Clubs Rishworth convention just around the corner, ive decided some long standing projects need to be brought back to the fore.

One of these is the Pye PF8 restoration. As of my last post on this subject, some time ago, the PF8 is working and crystalled for 433.500MHz, but, it is working poorly.

The reasons for this are that 433.5MHz falls within the T1 band 405-440MHz, but this radio was built for the U0 band 440-470MHz. Many of the tuning components are at their extremes in trying to bring the radio down to 433MHz.

One thing that can be done though, is to change the band critical fixed capacitors for the correct values for T1. By a stroke of good fortune, ive been able to obtain three of these from my spare PF8 'donor' chassis. If I cant find the other two amongst my junk boxes, then hopefully these can be found on saturday at Rishworth.

Changing these capacitors is only half the modification really needed, but im not able to swap the variable inductors, as I dont have a T1 chassis to find them on. But 433MHz is very close to the lower edge of the U0 range, so im hoping that by fitting T1 capacitor values, it will kind of fudge the set into being a T1-U0 hybrid. The PF8 is only capable of 500mW output and has an internal antenna - so every little helps!

I also could do with finding some modern batteries for it!

The Clansman GSA - More thoughts

I have been in contact with Martin G8JNJ, regarding the GSA antenna, he has provided some very interesting insight into the construction of the base unit, which im hoping can be expanded on to find a way to modify the antenna for best performance on the amateur bands.

Below I have copied Martins comments -

The transformer is a variation of a standard UNUN. The winding ratio is approx 3 which gives an impedance transformation ratio of 3 squared = 9.

Its actually slightly less than this as one winding has fewer turns.

The input impedance of the transformer will reduce to a very low value of impedance at the lower end of the frequency range. So the input resistor and parallel capacitor are intended to add extra series resistance which will increase in value as the input frequency is decreased. The intention is to try and make the input match more like 50R across the whole operating range. However this does mean that the efficiency on the low frequencies will be quite poor, as the resistor will be dissipating a large proportion of the applied power.
 As expected the power resistor is intended to fool the radio into thinking it has a good match and driving maximum power. Now, if the antenna was designed for just one small frequency band, say 70-71MHz, then this lossy resistor would not be required. Whether an arrangement of element lengths can give a suitable match without the resistor but also without any serious re-engineering of the UNUN, I dont know yet, but its worth considering.

Below, reproduced by Martins kind permission, is his better diagram of the internals of the GSA - 

Monday, 17 October 2016

PRC-320 Remote VFO - Why not a DDS?

Ive been asked this several times recently - why go to all the trouble of taking control of the PRC-320s synthesiser, with all the attended difficulties of isolating the decade switches when in remote etc, rather than simply replacing the sythesiser in its entirety with an AD9850 or Si5351 DDS module and Arduino controller?

So i'll explain. Yes, I could remove the synthesier module 9, and VFO unit 3h and replace it with a DDS, using the Arduino to read the decade switches directly....

... and the radio will never work properly again!

Sadly, study of the service manuals reveals that the synthesiser not only controls the VFO, but it also provides the variable control voltages that tune the RF stages, generate the out of lock tones, phase error outputs etc. Recreating those control voltages would likely be a very difficult task. I suppose it could be done, but its not something I have the time to do im afraid.

Im hoping the Arduino stuff arrives soon, as its about time I made a start with the control code anyway!


With my Clansman manpack collection now very nearly complete, the time has come to do a bit of consolidation, and find sensible storage!

I find myself now with an excess of PRC-349s! and their batteries! So the first task is to find new homes for these,

three sets are already earmarked for movement across the pond to the former colonies, subject to the formalities of receiving payment and setting up tracked shipping. Three more remain in search of a new master, whilst three sit quietly in the workshop awaiting refurbishment. Some excess crypto is also on its way shortly to a new home.

More importantly though, I need to find a better way to store it all out of the way when not in use!

Sunday, 16 October 2016

The Clansman Ground Spike Antenna Laid Bare

Regular readers may have noticed, that I like to see whats inside things, and how they work. Now, most of us who play with vintage radio, military radio, or ham radio in general, will understand this, and have probably had either a sneeky peek inside your rigs, or been in them from necessity of repair and alignment. But, there are some bits of kit which always seem to remain a 'black box'. The Clansman GSA base unit is one such item.
GSA Base Unit

But, thanks to Mick over in Barnsley, I have two of these, so tonight the curiosity was too much, and I decided to find out what makes this unit tick!

Well, one thing that is very obvious when you open one of these, is the coax wound balun

All well and good you might say, lots of antennas have a balun. But, this is military kit - its designed to work in the worst of conditions, regardless of the abuse it receives, and to be used by non-specialist squaddies. It has to work whatever frequency its put to, without any adjustment or alignment, and without a proper, efficient groundplane.

How it achieves this, and just why it often seems not to perform as well as might be expected, becomes apparent as we look under the balun -

Yes, thats an 18 ohm power resistor! The GSA is a resistor terminated antenna.

The result is that resistive loss factors dominate over inductive or capacitive, smoothing out the  impedance curve, and resulting in a flatter VSWR across the design range. The result is that although the antenna itself might not be always as efficient as it could be if properly matched, the load the radio sees remains reasonable at all frequencies and so maximum power transfer is maintained.

A rough schematic of the antenna is shown below. Note that im not very good with balun design, so please dont try to rewind one based on my diagram!

At first, this might seem a get out, too much of a compromise, perhaps even a poor design to save costs? But no, of course not. The build quality shows that. Its a simple fact - in the field, getting the message across is paramount, and the kit has to work regardless of the abuse it gets. As amateurs we are often dismissive of the ranges given in the Clansman manuals, as we get much greater ranges - but these are naturally conservative, worst case figures. Its the old adage in military radio - make the rear echelon station take the brunt of the link effort!

I also now have a respirator microphone! It will likely never be used for actual comms, but Halloween is coming up soon...

Saturday, 15 October 2016

Box full of boxes

Awaiting me when I checked the racks in the postroom today was my parcel from Graham at PTS Norfolk. I'd been looking forward to getting this, but was very pleasantly surprised when I opened it!

It contained as ordered the CRS L/R box, the Drivers Box, a trailing wire VHF antenna, and the straps for the PRC-350. There was also a small packet of handset clothing hook screws, which I was not expecting. I had emailed Graham to see if he had these, and was intending on adding a couple to my next order. But the surprise was the handful of PRC-349 case screws that Graham had said he would throw in for me - they were still in PRC-349 cases!

Not only that, but they have varying other parts still in them! From these I will be able to get the two radios ive repaired into usable state. My thanks to Graham, great service as usual.

Now that I finally have the Drivers Box in my possession, I can take a look at what im up against. The photo below shows the electronics inside

Inside 'Interconnecting Box Drivers Box'
One aspect that I hadnt appreciated, and might throw a spanner in the works regarding my planned modifications, is the three position switch - the third position is spring loaded and momentary! I will have to see if it is possible to make this a normal position (it is an open frame wafer switch), if not, i'll have to think how best to use the feature!

But that bit of engineering might have to wait a short while, whilst I finish off some more pressing projects and repairs, including several household tasks. Most of yesterday was spent demolishing and then rebuilding the steps to the workshop, and now my electronics benches are temporarily inaccessible whilst I play the part of upholsterer and repair broken dining room chairs!

Wednesday, 12 October 2016

Portable WSPR beacon?

On the 22nd this month, its the G-QRP club Rishworth Convention, and as I understand it QRP Labs will be in attendance.

Now, Ive been wanting a stand alone WSPR beacon for some time. So, with Rishworth coming up, I have my beady eye on this

Ultimate 3S Beacon

Based on an ATMega microcontroller (essentially a special to task Arduino!) and a Si5351A DDS module, this little machine is capable of putting out a few hundred mW on a selected band (decided by which plug in LPF is chosen) in many digital modes, such as WSPR, QRSS, JT65, CW etc etc. There is a GPS module for it as well, which not only disciplines the clock for accurate timing and frequency, but also automatically sets the locator!

If I go for the uncased beacon, with GPS, and an extra LPF for another band (perhaps 40m and 10m?) then its likely to set me back about £60, around half my Rishworth budget!

Tonight, whilst running WSPR on 40m, I decided to take a short break to test the HSR (Hand Set Remote) and D-10 link to the PRC-351. As I had Speclab running on the PC, I put WSPR to Idle, set the DX-70TH to 6m FM, tuned it and the -351 to 50.500MHz, and had a little play watching my modulation 'off-air' on the spectrograph! 

About half an hour later, I started getting concerned at how my WSPR reception had fallen off! Then I realised i'd left it in Idle! D'oh!

Repurposing the Drivers Box - Internal Goodies!

Thinking more about how to repurpose the Interconnecting Box, Drivers Box, to form a combined Digital Modes Interface and Audio Test/Break-Out Box, I started to consider what might be inside one.

A couple of things were clear. There would be a switch, probably multipole, and a potentiometer. Beyond that all I could make out from the external view photos was the presence of the connectors!

But, thanks to Chris G8MKT, I am now in possession of EMER TEL L802, pt's 1 & 2, the Clansman Harness Technical and Repair manuals. And from pt.2, comes this wonderfully useful diagram -

This is the internal electronics and wiring of the Drivers Box. The first thing that strikes is that the switch is a 3-pole 3-way. This leads to the twin possibility of using it to select between Test/Break-Out and Datamode Interface. It also gives the possibility of having a through way and an attenuated setting for the transmit audio path.

The second, obvious item is the volume control. That will certainly be used on the receive audio path to control the level into the PC for decoding, as well as remaining a usable volume control for the Clansman audio kit.

More interesting though, is the presence of two transformers, and a relay! The datamode interface requires isolating transformers - could these perhaps be pressed into service there? As for the relay, it may be useful for PTT control.

One thing I do have to decide is how I will connect the completed unit to the radios. If I do so from one of the audio connectors, I require a plug to plug cable. For this it might just be best to use the cable for the loudspeaker, so I need to check how many of the cores are present in this cable to ensure I can make the required connections this way.

Interestingly, PTS Norfolk has the telephone cable terminals available at 75p each, or the sprung wire terminals for £2 a go. Using these would make the resulting project look very authentic!

Tuesday, 11 October 2016

Clansman Drivers Box - Repurposing?

I have a Clansman harness 'Drivers Box' coming. The original intention of this was to rob it of its two 7-way connectors, to make up various adapters that would allow me to break-out the Clansman audio connections for test purposes, or to allow non clansman audio equipment use, and to allow me to use Clansman audio ancillaries with non-clansman radios.

A further project is to build a datamodes interface for the Clansman system.

Now, im starting to think like this -

The Drivers Box has two 7-pin audio connectors, two 12-pin harness connectors, a volume control, and a multiway switch. And I dare say, plenty of room inside. So what then, if I use one of the audio connectors for connection to the radio, the other to a handset/headset, and engineer the rear of the box for jack connectors, a 9-way D-type for PTT control, and a set of 4mm terminals? Then reuse (if the value is suitable) the volume control as, er, a volume control, and the switch either replaced with a suitable potentiometer for mic level control, or a set of attenuators to give fixed level intervals? (after all, the main control of mic level for digimodes is done from the PCs control window)

Rebuild as multi-purpose audio interface?
The two 12-way harness connectors would be removed, and either the holes reused for other connectors, or given a filling of Plastic Metal! An LED mounted dead center would act as PTT/Tx indicator for digimode use.

On Air via Twisted Pair

Today, with some time spare, and having obtained a drum of D-10 twisted pair field telephone cable from Dom at LRSeries-surplus, I finally got to try out the HSR (Handset, Remote) that I picked up at this years Finningley rally. There are two curious aspects of the Clansman system that sometimes puzzle people -1, almost everything is designed with an audio socket to let you plug in a handset! and 2, almost everything is fitted with a D-10 wire stripper!

Also arrived this morning was the replacement 10m audio extension cable. I was just about to get dressed after a nice lazy morning when I saw a parcel van pull up, and knew by the marking on the carton that it was for me!  This replacement is due to the original cable being found to have slipped by with a deep cut that had severed many of the wire cores. Testing both, the replacement proved to be just perfect, but interestingly the damaged cable by sheer luck (bad/good?) had the wires to the earpiece intact! I suspect that any quick test of the cable by just listening for noise, which is how i'd have done it if i had a lot to test, would result in a pass!

I cut off around 15ft of D-10 for the HSR test. I found that I couldnt easily strip it using the stripper mounted on the PRC-351, so cheated there and used pliers. But by a 50/50 chance managed to connect the wire correct way around first time. Attaching the handset is easy, you simply feed in the wire, then pull it back and the Insulation Piercing contacts do the rest. 

Setting the radio to R, a quick check on * showed the audio was working, and going to transmit revealed good sidetone.  Setting to I (intercom) allowed for a successful but tricky test with just one person! A final check on C (Call) showed that the call tone worked just fine.

I only have one PRC-351 so cannot test it on auto rebro. Perhaps when the CRS L/R box comes...

I would have liked to test it on air as well, but as usual theres no 4m activity!

Saturday, 8 October 2016

Arduino Dew Heater Controller

Winter is coming, so its really about time I got around to building the Dew Heater for my camera lens/telescope, after all Ive had the heater element strap for ages!

I came across this Arduino project for just such a thing

so have decided to go with it. After all it seems to do what I require, so ive put in the required orders for the Arduino Nano, the humidity and temperature sensors, the OLED display (ooh, not played with OLED yet!) and the MOSFET driver. If nothing else, at least Sam knows what he's doing with Arduino's! Ive ordered two Nanos, as if one is going to be permenantly part of this project, the other is then spare for other development.

Ive also bitten the bullet and ordered an Arduino Mega. Looking at its dimensions, I think it might just shoehorn in the available space in the PRC-320, and with its 54 digital I/O pins and extra dedicated serial comms pins, its more than capable of handling the required number of connections for the Remote Control VFO project. Again, the easier to use development language and GUI makes it more likely i'll get somewhere with the project than the original idea of using PIC chips. I still think I could make PICs smaller, but the effort with the software would be far greater for a computer thicko like me. Plus the Arduino, being a self contained board, is much easier to prototype on the bench!

Of course, this means also that an Arduino, perhaps a Nano, could be used for the Remote part of the project.

Before I can do much on this though, I will need to sort out that dicky switch contact, or whatever the issue is, that is causing the frequency setting problem. But this is probably just the push I need to do that!

I think Mike Walker might be pleased ive decided to explore this route!

Chinese 24v SMPSU - Punt Taken

Well, ive finally taken a punt on a far east 24v 3A switch mode PSU module, with the intention of installing it into a de-celled Clansman battery pack to build a mains power supply,

Something like the one above (random stock photo). This plan rests on two aspects A) the bloody thing actually works (and by that I mean it has usable regulation, and controllable noise, not just that it actually produces 24v!), and B) it fits into an empty battery case! This last point is more about the 1Ah battery ive de-celled, where the specified dimensions are rather tight.

What I am hoping, is that the SMPSU will fit in the case, with sufficient room for a proper filtered IEC socket for the mains input (the ubiquitous kettle lead), and space by the LT terminals for more filtering if required and output fusing and indication LEDs, and perhaps a On/Off switch.
It might be worth the extra work, if the SMPSU is reliable enough, to add an external LT connection to allow other 24v items to be powered.

But, all is speculation at the moment - its got to get here from Hong Kong first!

On a more contemporary note, my items ordered from Dom at LRSeries were waiting for me at reception this evening. Unfortunately theres a small problem with the audio extension, but were in the process of working that out. The handset pouch is spot on, and once I decide which rig to marry it to it will be attached to a strap and have a handset inside it! Also part of this consignment is the canvas dispenser pack of DON-10 twisted pair telephone cable. My gawd I had forgotton just how heavy a drum of DON-10 is!

The label on this says 2/3, so theres somewhere over 400m of wire in it. Should do for a few remote test sessions! Trouble is, its got me pondering looking for a pair of PTC404s!

Ive also taken the plunge and put the Yaesu FT-290 up for sale on ebay. I have to face the fact that im probably never actually going to get around to fixing it! Who knows, it might raise enough to get a small FM only set to add to the shack for monitoring S20 traffic.

Thursday, 6 October 2016

What To Do? - Yaesu FT-290mk1

Some of you might know that as well as these blogs, I also am the group owner and moderator of the Yahoo group 'Electric Handbag', dedicated to, primarily, the Yaesu FT-290R mk1 2m multimode transceiver, but also the mk2, and the 6m and 70cm equivalents.

But I have a dilemma, one of my mk1s needs some minor repair work, but I have neither the time nor knowledge of its particular issue, to put it right. But this radio has a Mutek front end fitted!

Do I hold onto it? Or do I cut my losses and move it on? It is actually usable, despite the fault, which is some form of imbalance on the SSB side, resulting in carrier leakage. It also suffers from the 'End Stop' fault, but so do almost all of these radios! Oh, and the LCD backlight needs replacing, and it wont work on battery as the cell holders also need replacing!

If I sell it, I could put the money towards obtaining a mobile mount cradle for my other mk1!

I have it powered up at the  moment, just to recondition it after the time its spent on the bench. Perhaps it would raise enough gelt to let me get a 2nd hand FM only set as well, just for monitoring local traffic.

Wednesday, 5 October 2016

Projects and Collections

Its now autumn, so soon it will be time to think about winter projects. I have rather too many things that I really need to finish!

Principle amongst them, is the Theremin! As this isnt mine, but a commission project undertaken quite some time ago, I really must complete it! Likewise, my 4m Transverter, which has been sat awaiting a Tx section for years now! And very importantly, I need to complete the refurbishment of my Pye PF8!

But my Clansman collection should be complete before then. There are a bare dozen items I still require, and a good number of those will be with me soon. The CRS L/R box and its cable, the PRC-350 carry straps, the trailing wire antenna, and a Drivers Box from which to salvage the audio sockets I need to make up test adapters, are all already on their way courtesy of Graham at PTS Norfolk.

Soon, also, the audio extension cable, Handset pouch, and a roll of D-10 cable, will be coming from Dom at LRSeries in York. Thats assuming ive done the invoicing right!

So that just leaves a handful of items such as the bench morse key, Hand crank charger, PRC-350 battery extension, and the S10 respirator microphone, oh and a Jamcat! All minor items and of no immediate requirement for actual on-air operation.

Im also having to force myself to step away from the auction and NOT bid on a WS31 set! I need to keep telling myself that its neither Clansman nor WW2 vintage, and it doesnt work on any amateur bands! Instead, I must get on and complete other projects!

Oh, and I wonder, since I have the picture, if anyone has ever been curious as to the insides of a 4W SURF? Well, here it is -

The answer is, pretty much nothing, but what there is is very well made. Theres an air spaced variable capacitor under the PCB, driven by a worm screw from the knob on the front. some inductors, hidden away, and the reflectometer circuitry to drive the meter. And thats it.