Thursday, 25 December 2014

Sending Christmas Greetings to the ISS

There was much media coverage in the UK of the "Santa pass" (Telegraph, Daily Mail) The International Space Station passed over the UK in the late afternoon and early evening on Christmas Eve and around 17:20GMT promised an especially bright display in the dark skies. So imaginatively we were asked to observe and imagine that the bright moving point of light was actually Santa off delivering his presents.

As luck would have much of the UK had a crystal clear sky and I even managed to get my 80 plus year old Mother-in-law out in the garden to watch the spectacle. She was impressed and it was great to overhear lots of excited children coming out in the nearby homes to watch Santa as he flew overhead.

Back in October 2013 after becoming a newly licensed radio amateur I managed to send APRS packets to the International Space Station which were digipeated and received back on earth by other operators. Back then I used a lowly Baofeng UV5R handheld and I decided to repeat the exercise this time using the FT857D (this time running around 20W) to talk to Santa!

The computer I used back then has been decommissioned so on the laptop I installed the UISS program from ON6MU which makes easy work of APRS to the ISS and instead of the cumbersome AGWPE I used the excellent soundcard modem from UZ7HO.

I attempted to send a message on the pass at 15:43 but failed completely, discovering I'd got my soundcard incorrectly set up. I corrected this and left the autobeacon mode running in UISS during the Santa pass and checking back much later could clearly see I'd sent and had a message repeated back from the ISS.

Checking the ariss website ( I could see the repeated message had been received by another station and my position was showing up on the map (M0NRD)

I have successfully done it again today on Christmas Day! As the raw packets below confirm.

M0NRD>CQ,RS0ISS*,qAR,DM2RM:73' Happy Christmas from Andrew IO93OB
M0NRD>CQ,RS0ISS*,qAR,MB7USS:=5304.08N/00048.47W-73' Happy Christmas from Andrew
M0NRD>CQ,RS0ISS*,qAR,HG8GL-6:73' Happy Christmas from Andrew IO93OB

It was a nice achievement and another nice Christmas present was achieved early this morning while running WSPR on 40m, managing to get received in New Zealand

Anyway enjoy the rest of the festive season and I wish you all the best in 2015

Sunday, 21 December 2014

Another year gone...

Today I celebrated my birthday and reflecting on the past year I realised just how much I have achieved during my first year as a bona fide radio amateur.

While I gained the foundation licence back in September 2013 it was only at the start of the year that I took possession of my first proper radio and began my first real forays into the hobby. That is not to say the end of 2013 weren’t without its highlights, remember ICube-1?

While the foundation level licence gave me access to most bands, be it at only 10W, I was not content to stay as M6GTG. I passed the intermediate in May (2E0NRD) and finally got the full licence in October (M0NRD) and have slowly been honing my operating skills.

I competed for the first time in the RSGB UKAC and other VHF/UHF contests. They have proved to be an enjoyable and educational activity. The structure exchange helped me overcome my initial microphone shyness and the goal of improving my score each week to become more competitive forced me to improve my set up.

Construction of a headset interface and the addition of a foot switch were simple projects as was the building of a simple but effective Moxon antenna for 6m (blog post). This together with a permanent antenna pole, rotator system and upgraded coax all have helped me improve and learn. I even tried my hand at some portable operating with varying degrees of success. I have received some invaluable help and advice from people, especially Robert G1ZJP (M1MHZ) The results for the year have been coming in and I am very happy with my final positions in the various bands for a first timer and hope to be more competitive next year. .

HF operating proved initially off putting, plagued by QRN/QRM and my initial microphone shyness I veered toward the more noise immune data modes. I built a data mode interface and have had a fair degree of success with PSK/JT65 and RTTY as dabbling with a few other modes and over the last few weeks I have experimented with FreeDV and find it fascinating.

As I have become more confident I now operate voice more often and now regularly give points away on contest weekends because I like the short formalised exchange. Indulging in small talk in normal contacts is something I am not good or comfortable with but as I’ve got to know local operators I have started to join in the local nets and art of conversation is becoming easier.

The High Altitude Ballooning (HAB) has taken a back seat at present. I still have active plans to get a flight up with my own payload and have given a number of successful talks to local clubs over the year which I have enjoyed. Missing the UKHAS conference was a bitter disappointment but I still track flights and I hope to reinvigorate this interest in the spring as I get back up to speed with recent developments. 

Due to time constraints I have also mothballed plans for numerous construction projects based around the Arduino. Last months rearrangement of the shack should allow me to finally get around to finishing them.

Operating the JOTA station GB2FFC for a local scout group was very rewarding. The write up from this blog was included in the latest RSGB Radcom magazine and we hope to do it again next year. Being asked to contribute content to the website came as a surprise and thanks to all those who have commented on my ramblings.

Another rite of passage was managing to repair my first rig, an elderly TR9500, yes it was only a modest achievement but a massively satisfying one and it has given me some confidence in purchasing second hand equipment in the future.

As well as building up the shack and continuing to improve my setup and operating I have some specific aims for next year...

Make a proper satellite contact
Satellite reception and tracking is something else that has been neglected recently, though I am still decoding FUNCube-1 telemetry daily.

Make a meteor scatter contact
I attended a fascinating presentation at the Spalding and District ARS by Robert G1ZJP about Meteor Scatter operating just before the Perseid meteor shower. I have made a couple of attempts since including during the recent Geminid shower and while I can receive signals no problem I have yet to make a successful contact. It is definitely on the to-do list but I may need to increase the power output, maybe even investing in some amplifiers and better antennas who knows it could lead to attempting some EME!

Make a proper SOTA/IOTA activation
Next year I will be holidaying in Scotland on the Isles of Skye and Islay so want to make a better attempt at operating in these more remote operating than I did this year. I also want to take a radio up a mountain!

Become more involved locally
I joined the South Kesteven ARS last year and regularly communicate with members of the nearby Grantham ARC. There have been suggestions of operating special event stations as well as repeating the JOTA event. I enjoy the meetings and conversations and is nice to bounce ideas off each other and hope to be more involved in organising activities.

Anyway, still a few hours of my birthday left so off to enjoy a wee dram or two and a slice of my birthday cake made by loving XYL

Sunday, 7 December 2014

Repairing a Kenwood TR9500, Part3

Back in September I attempted to repair a Kenwood/Trio TR9500 UHF All-modes transceiver for a fellow club member. It had a faulty microphone pre-amp which I replaced and all seemed well but it had further issues with the receiver. Cutting his losses and wanting shot the owner sold it to me for the princely sum of £10.

I have had her back on the bench and initially couldn't find anything wrong. However in real use it become apparent that she was in fact profoundly deaf! Picking up test transmissions from the nearby FT857D or Baofeng outputting into a dummy load was one thing but it wasn't receiving anything else!

From the service manual and schematic I deduced that it could be the initial RF receive amplifier. It is a dual-gate mosfet (3SK76) It proved tricky but I managed to source a replacement on eBay and it was a simple job to replace once I'd extricated the PCB.

I can report it is now working and the video below shows it monitoring the GB3EE repeater in Chesterfield. From the coverage map I shouldn't be able to hear it but I can and reception has been marginal at best using other receivers but it repaired TR9500 doesn't have any problems.

I wonder if the rig has been subjected to a high RF field in the past this could easily have damaged the receiver amplifier and an induced RF into the microphone lead could have damaged the microphone pre-amp. It just seemed strange it having both faults.

Tuesday night is the last 432MHz UKAC contest and hope to use her in anger.

Sunday, 30 November 2014


This weekend I have managed to get the FreeDV program working successfully and made a couple of QSOs on HF.

FreeDV has received a fair degree of publicity recently and is a GUI application for Windows, Linux and MacOS (other platforms are in development) that allows any single side band radio to be used for low bit rate digital voice communication.

I was primarily interested in it for possible use on VHF. It is hoped that the recently introduced 146-147MHz allocation available in the UK to full licence holders (via a Notice of Variation) will be used for digital mode experimentation. I have been constructing a data mode interface for use on the old TR9000 since it can operate on these frequencies but I decided to try the FT857D on HF to get an understanding of the program.

With FreeDV speech is compressed down to 1600 bit/s then modulated onto a 1.25 kHz wide 16QPSK signal which is sent to the mic input of a SSB radio. On receive, the signal is received by the SSB radio, then demodulated and decoded by FreeDV. The appeal being communications should be readable down to 2 dB S/N, and long-distance contacts should be possible using QRP power.

There is a lot of information. videos and guides available on the FreeDV website but the basics are straightforward. The computer requires two sound cards to handle the audio to and from the radio and the speaker/headphones and microphone. One method is to use a USB 'gamer' headset but since I already had a spare PC headset with 3.5mm plugs I opted for a cheap plug in USB soundcard (as detailed below)

Once the audio devices and PTT control are installed and configured within FreeDV it is a matter of monitoring a frequency (in USB) and hopefully you can send and receive.

So far I have only managed two QSOs with Trygve (LA6UOA) and Fabrice (F4FPG) on 14.236MHz with both the audio was clearly understandable but did suffer from the odd breakup and stutter. This was probably due to the laptop being used rather than an issue with the signal as the FreeDV needs a reasonably powerful machine with a decent amount of memory.

The software is very picky, several times the audio device settings have been forgotten or it has come up with a cryptic error message:
../src/msw/bitmap.cpp(846):assert "image.IsOk()" failed in
CreateFromImage(): invalid image
This is a known issue with the Windows version and the solution is to manually remove all of the FreeDV settings from the registry. The full details of how to edit the registry are in the GOTCHA section of the FreeDV site. Editing the registry is not recommended to the inexperienced person so is not a great solution and when starting the program backup after this fix requires reconfiguration of callsign, sound card and PTT settings again.

Despite this setback it is an excellent and exciting new mode. Both Trygve (LA6UOA) and myself were first timers when we had our QSO and we were like excited school children once we were able to converse successfully. Fabrice (F4FPG) was an old hand at it and I thank him for allowing me to briefly interrupt a QSO he was having with another UK operator who I could not hear.

I would recommend using K7VE's QSO Finder website to see who is monitoring and on what frequency as well as passing hints in real time.

Tuesday, 25 November 2014

FTDI still bricking chips?

I doubt anyone missed the recent FTDI driver controversy.

The Scottish company Future Technology Devices International (FTDI) released an updated version of their USB-to-Serial driver for Windows on their website late September and last month the driver became available via Microsoft Windows Update. It soon became apparent that these new drivers could 'soft brick' counterfeit and software-compatible clones of their chips by re-writing the USB product ID (PID) to "0000". This action prevents the chip from being recognised by drivers of any operating system, effectively making them inoperable unless the PID is changed back. This clumsy and ill thought out measure was intended to protect its intellectual property.

The ability to reprogram the USB Vendor/Product IDs is a feature of FTDI devices offered to equipment manufacturers and so most bricked devices could be reset by using the downloadable FTDI utility.

Obviously there was much outrage from the hobbyist community and FTDI were roundly criticised and as a result the malicious driver was supposedly removed from the Windows update system.

Or so I thought...

I am currently constructing another data mode interface for some experiments with FreeDV. It requires the usual PTT control driven using the RTS line from a serial port. I purchased a couple of simple TTL level interface boards on eBay which claimed to use FTDI chips.

I built up a little scrappy veroboard circuit with an open-collector drive transistor and plugged into the shack PC and everything seemed okay as this PC already had an older FTDI driver installed.

I am using another computer for the FreeDV experiments and plugged the board into this thinking it too already had a safe FTDI driver installed but instead it brought up the installing driver dialogue and appeared to go online and download drivers and install them. I really didn't pay much notice as I wasn't too worried as any malicious drivers had supposedly been pulled and sure enough after installation everything appeared to work, the port appeared in device manager.

I unplugged the board to make a slight change and was surprised when I plugged it back in the PC the driver installation dialogue reappeared followed by an error message saying driver couldn't be installed and contact the manufacturer.

The serial port now appeared in the device manager with a yellow exclamation mark saying no driver installed error 28. Examining the device details showed that the VID was still 0403 but the PID was 0000 it had been bricked! Unfortunately not soft bricked as I have been unable to reset the chips PID using the FTDI utility.

I am not exactly sure what has happened but still a case of beware when it comes to FTDI devices and I shall be avoiding them from now on.

Saturday, 22 November 2014

Yet another shack clean up

Back in January when I took delivery of the FT857D I reorganised the shack, disposed of lots of surplus junk and the resulting layout has served me well for most of the year.

As I've acquired more equipment I have found myself struggling for space and the cluttered workbench has prevented any proper construction.

Following a rearrangement in the house I had a spare 'desk' which I wanted to make of, so the plan was to move the workbench and put the new desk next to the existing desk. I had some bookshelves which were being used inefficiently and I almost threw them out but decided to make use of them by cutting them down and modifying to make new shelves to sit on the back of the desks.

I had another clean out and the remaining junk is now in large plastic storage boxes under the desk should it prove useful one day. It is still a little cluttered but I have much more room with proper access to my books and magazines.

The workbench is at the end of the shack directly under the overhead light

 It is a work in progress, but it is a much better place to work and operate in.

Tuesday, 21 October 2014

GB2FFC - JOTA 2014

Last weekend South Kesteven Amateur Radio Society (SKARS) operated the GB2FFC special event station at the First Foston Scout Group for the 2014 Jamboree on the Air (JOTA) weekend.

JOTA is an annual event in which Scouts and Guides all over the world make contact with each other by means of amateur radio, giving them an opportunity to experience wireless communication and electronics.

This was a first for both SKARS and the Scout group and we set up a SSB voice station and a data mode station primarily running PSK. The QTH was the Scout hut in the village of Foston, between Newark-on-Trent and Grantham (IO92PX)

Nigel (M0CVO) and Sean (M6ENN) ran the SSB voice station as well as supervising the popular Morse key trainer. This allowed the children to tap out their names using a crib sheet and gave them a certificate to acknowledge their achievement. Working voice proved challenging due to the high noise level in the hut due to the other scout activities. Despite this they still managed to work stations mainly on 20 and 40m. Nigel ran a Kenwood TS-480SAT into one of his own M0CVO DBD-2040 loaded dipoles at approximately 100W

I operated the data station consisting of my FT-857D and interfaces connected to a laptop running PZTLog feeding a M0CVO Magitenna at 30W. I also had my Czech morse key connected to the TR9500 acting as a sounder and they really like the military style key.

Explaining the PSK datamode and what the program was doing to young children was quite challenging. The Scout group were also running JOTI (Jamboree on the Internet) which consisted of laptops running an IRC chat application allowing world wide groups to talk to each other so the distinction between that and the slower PSK station was a bit difficult for some of them to grasp. Thankfully there were two very intelligent and enthusiastic Scouts who got the idea and understood the QSO process and were soon explaining it to the other Scouts leaving me free to type and push the macro buttons. One of them described it as 'awesome!'

GB2FFC ran from 09:00-15:00 UTC on the Saturday and 12:00-15:00 UTC on the Sunday and made 88 QSOs in total, mostly other amateurs but we did manage a number of other JOTA stations in both modes. The whole event was great fun and we were made very welcome by the Scout group. The enthusiasm was infectious so hopefully it will be the start of a regular annual club event helping out the Scouts for JOTA - plans were already being sketched out for next year, maybe involving camping!

Here are the PSK QSO maps for the weekend. Saturday was on 20m and 15m and were just European, Sunday I was operating mostly on 10m hoping for some transatlantic contacts, and did make a couple in the short time we had - didn't quite manage to connect with some South American and Asian stations but they could be seen and decoded to the delight of the children.


Monday, 20 October 2014

Over The Moon - M0NRD

I now have a full licence and a new call sign M0NRD.

I sat the advanced level examination held during the RSGB Convention on the 12th October. The results were due at least six working days later so wasn't expecting to know how I had done till this week so I surprised when the certificate arrived on Saturday morning and was over the moon to discover I'd passed with a distinction.

I only decided to apply to sit the exam last month. Regular readers may have missed the announcement as it was an after thought at the end of another post.

I became a licensed ‘foundation level’ radio amateur last September (M6GTG) and an ‘intermediate’ (2E0NRD) in May this year. It was a bit of a bold decision to attempt the final stage as I hadn't been actively studying for it. There have been many people who have progressed in a shorter time but going through the levels in just thirteen months is a big undertaking especially when time and concentration is taken up with work, career and domestic commitments.

After a cursory glance at the syllabus and a quick leafing through the RSGB Advance! book I had decided while there were quite a few areas that I didn't know in depth the electronics theory and mathematics were okay due to my higher education background (though it has been 26 years since I left University) so I just needed to fill in the blanks.

After posting off the application the plan had been to spend the month going through the book, learning, refreshing and revising the subjects as necessary. Of course I got sidetracked and distracted so it got left it to the last minute, well in fact to the week before the exam.

As soon as I started studying properly I soon realised I'd seriously underestimated the amount of details and facts that I need to understand and recall. I knuckled down and despite doing full days at work I studied in the evenings, making notes, working the questions on the Hamtests website and in the QADV program and gained confidence of getting at least the 60% pass rate. I tested myself on the QADV practice papers and mock papers on the RSGB website and seemed ready.  

I had intended to be at the RSGB Convention proper however I agreed instead to spend that weekend at the Mother-in-laws in Cambridge and drove over to Milton Keynes in thick fog on the Sunday morning.

The actual exam seemed reasonable there were a few head scratchers and several questions on topics I suddenly found myself unsure of. I took my time deliberating and checked every single 'licence condition' question against the supplied licence document even if I thought I knew the answer. Double and triple checking questions, values, calculations and answers and with 10 minutes of the alloted time remaining I had filled in the marking sheet and made a quick exit in time to get my Sunday roast dinner.

I had left confident and reasonably happy but over the next few days doubt inevitably started setting in. I kept remembering questions.. had I got that one wrong? I resisted the temptation to check the text book and keep thinking well it is only 60% I need...

To achieve a distinction was very satisfying, a lot of people have said they expected me to walk it but self doubt and a lack of self confidence is something I have suffered from for many years. When I was a spotty student I would probably have agreed but now an overweight, slightly befuddled middle aged man with greying hair you do have your doubts.

I would like to thank all those people who have congratulated me and those who have encouraged me along the way and wish everyone studying and taking the exam in the future the best of luck.

Wednesday, 8 October 2014

The TR9500 and her sister come to stay

The shack has gained a couple of 'new' radios, one of them look familiar?

It is the Trio/Kenwood TR9500 that I repaired last month for a fellow club member. Having no transmit audio I'd replaced a faulty transistor in the microphone pre-amp. Subsequently it's owner reported it was still misbehaving and locking up in transmit mode.

I'd offered to give it another look but the owner decided to cut his losses and wanted shot of it. He had just purchased a nice new radio at the National Hamfest and was also selling a 2m Trio/Kenwood TR9000 multi-mode set to make some room.

I liked the look of these pretty sisters and got both of them for a very reasonable price, the TR9500 costing just £10 in lieu of the previous repair work. I collected them at the weekend and got around to checking them out last night.

The TR9000 is a lovely compact rig, the case has the odd scuff but the front is in good condition and has cleaned up nicely. I just need to attend to the microphone plug as it wearing the ubiquitous piece of brightly coloured insulating tape. It is fully functional and I made a few contacts on it during last nights 144MHz UKAC. It is nice sounding and seems to have a good sensitive receiver.

The troublesome TR9500 has been back on the bench and connected to a dummy load and my X-50 dual-band collinear and I cannot find anything wrong. The ALC 'issue' I suspected was a red-herring, the audio does cuts out and the S-meter goes to S9 but only when the RF gain knob is turned to minimum not maximum as I'd thought, the same thing happens on the TR9000.

It is entirely possible the fault reported by its previous owner is intermittent (a bad joint, sticky relay etc) It is also a possibility that RF was leaking back in the rig causing it to lock up. I plan to use it in anger maybe during next weeks 432MHz UKAC especially if the receiver proves as sensitive as that in the TR9000. 

As I mentioned the National Hamfest took place recently and since it is local to me I decided to go along on both days. The Friday was by far the busier day with lots of sellers in the outdoor flea-market with a genuine 'buzz' which seemed lacking on the Saturday, there were a lot less sellers outdoors.

The main hall left me a bit underwhelmed, the layout seemed a bit messy and some areas were cramped while others seemed to have acres of spare room. It was also very hot in the main hall especially on the busy Friday, however it was still an enjoyable couple of days and met up with some fellow tweeters and operators. 

My purchases were modest and as well as the usual connectors and cabling I picked up a nice as-new 7A regulated linear power supply, a foot switch, a replacement satellite Quad-LNB, a very sorry looking 70cm linear amplifier and picked up one of those lovely Czech morse-keys for when I brave doing the code!

I also picked up this little 2.4GHz B/W video monitor for a whopping £1 and it works a treat. I have a number of 2.4GHz wireless security cameras (purchased back in 2009) intended for a PC-based PVR CCTV system but the whole PC system proved unreliable so they are sitting idle. This little monitor can receive on the four standand channels and as a bonus runs off 13.8V so ideal for sticking in the car and driving around the local housing estate eavesdropping on other similar cameras - I am joking of course!

The very sorry looking 70cm linear amplifier is a Tokyo Hy-Power HL-60U. I found it hiding away in a box of junk on one stall and after a bit of haggling got it for a fiver! From its appearance I really didn't expect it work, especially since the warranty seal had been broken. I wasn't too bothered about the power amplifier I was far more interested if the built in GaAsFET pre-amplifier still worked.

Getting it on the bench I opened the case, expecting to find it plundered and butchered and was pleasantly surprised to find the insides looked almost pristine. I think the main PA transistor may have been replaced, but while it looks a bit messy the flux resin around its joints looks the same as other areas of the PCB so not sure. It looks slightly different internally to some another photographs I found on line and I have searched the web for a manual and schematic with no joy. Tokyo Hy-Power went bankrupt last year and the website and precious data downloads have all but disappeared.

As it looked intact with nothing missing I connected up the dummy load, power meter and fed the input from one of my Baofeng handhelds. It powered up and was giving 15W out for a measured 3W in with no distortion on the audio, so far so good. However after connecting up the FT-857D and slowly increasing the input power is became apparent that 15W seemed to be about the limit of its output, not the 60W as promised.

Removing the dummy load and putting it on the X-50 antenna I had a listen around for weak stations to checked the operation of receive pre-amp and it worked! Should prove useful for the 70cm contests.

Friday, 19 September 2014

Radiosonde Decoding

Weather balloons have been routinely launched into the atmosphere for many years by government and commercial organisations for the purpose of scientific and meteorological observations and research. Hundreds are launched daily around the world, using predominately renewable Hydrogen as the lifting gas.

These balloons invariably carrying radiosondes, a battery powered telemetry instrument package to measure various atmospheric parameters and transmit them to a ground receiver. Worldwide they operate on radio frequencies around 400MHz and 1680MHz.

Last year I discovered the hobby of High Altitude Ballooning, where enthusiasts send up their own balloons loaded with experimental payloads and radio telemetry trackers using low power transmitters and amateur radio data modes and frequencies. I have since had a great deal of enjoyment receiving and decoding these as well as developing my own payload.

I decided last year to also try my hand at decoding the commercial radiosondes. Reception of the telemetry signals is relatively straightforward as they are of higher power than the hobbyist transmitters and decoding can be done by the Sondemonitor program from COAA available to individuals to produce graphs and charts of temperature, pressure, humidity as well as the location (if transmitted) and height of balloons.

The software is available for a 21 day trial but when I attempted to install it I was thwarted by a licensing issue caused I believe by installing trial versions of COAA's ShipPlotter and PlaneSpotter programs in the past, despite this I still decided to purchase a software licence for the princely sum of €25.

However this was just before the Christmas upheaval and the dismantling of my receiving set up and so it got mothballed and I have never got around to using it till now.

It was quite by chance that I was flicking around the SDR yesterday using my original (Version1) FUNCube Dongle PRO when I spotted a Radiosonde signal on 404.2MHz, my interest was piqued. (It should be noted the later FUNCube Dongle PRO+ unfortunately has a coverage gap on this frequency so cannot be used)

I connected to my magical HAB antenna and using SDR# and the Sondemonitor program I received and decoded my first radiosonde early this morning and a second flight around noon.

The program produces some interesting graphs showing temperature, humidity, pressure and other measurements during the ascent and after the balloon burst, as well as Tephigrams.

I am not sure where these balloons are launched from. The Radiosondes are identified by the software as Vaisala SGP models (but have no GPS data?)  Checking the Vaisala website there are a number of devices and one downloadable document is a comparison of the Vaisala Radiosondes made by the UK Meteorological Office in 2013 (pdf file) which mentions a site in Camborne in Cornwall, but I have also seen mention elsewhere of a site in Larkhill on Salisbury Plain.

The Met Office document also hints that the Radiosonde currently used by them is one of the Vaisala RS92 range, indeed the RS92-D appears to be a device which has no on board GPS and would fit with the GPSless decodes I have made.

Definitely another interesting radio diversion and if you are interested then reception can be made using RTL-SDR receivers as this tutorial on demonstrates, but bear in mind the demonstration/tutorial shows GPS information being received which I have not seen on either of the two launches.

Wednesday, 10 September 2014

Repairing a Kenwood TR9500, Part2 - TX working, SSB RX not

As I suspected the microphone amplifier Q1 in the Kenwood/Trio TR9500 was indeed faulty. The replacement arrived next day and within an hour I had successfully soldered in the new 2SC2240 transistor and it now had audio on transmit.

Transmitting into a dummy load and monitoring on my FT857-D the FM transmission was fine, the SSB was okay, perhaps slightly over driven. I suspected that maybe the previous owner might have twiddled something to compensate for a failing Q1.

In the adjustments section of the service manual VR6 on the IF unit controls the SSB MIC gain. To check the settings it was a case of setting the transmitter to 432MHz and putting an audio frequency signals of 1.5kHz of amplitude 1mV and 10mV from my signal generator on to the microphone terminal, and observing the RF power output, which were the 5W and just over 10W as required. As this didn't need altering I left it alone and boxed it back up and returned it to the happy owner.

Last night was the RSGB 432MHz UKAC Contest and I was hoping to here it on the air, sadly I didn't. It now transpires that there maybe another issue with it, something I should have spotted.

I do remember something strange when doing the initial testing. Connected to a dummy load and in SSB mode the S-meter showed S9+ when in receive but with no audio, turning the RF gain control the meter dropped to S0 and normal white noise static could be heard. It received a SSB transmission from the FT857-D with no issue so I thought no more of it. Being over eager and not experienced with using different rigs I had mistakenly dismissed it and should really have read the operating manual more extensively.

The anomalous S9+ meter reading and no audio occured when the RF gain control was set to the maximum which is the normal recommended setting for operating, I'd simply turned the RF gain control to the minimum mitigating the issue.

Obviously the rigs owner had put the RF gain back to maximum and was now reporting it wasn't switching back to receive. In fact it is but nothing is being heard. Checking the service manual this morning and it appears there is an issue with the AGC circuit (description and block diagram below)

.... The signal is picked up from the last stage of the IF amplifier (Q23), then detected and amplified to generate the AGC voltage. The AGC time constant is automatically set according to the mode : FAST for CW; SLOW for SSB. The AGC voltage is applied to IF amplifiers Q21, Q22 and Q23 (3SK73(GR)) and RF amplifier Q51. It is also used to drive the S meter.

It seems the rig may well find itself back on the bench, however this repair could be more problematic!

As I mentioned it was the 432MHz UKAC last night and I had a decent night of search and pounce. Conditions were very strange, lots of fading and strangely some of the usual local operators were not heard. I was very pleased to catch some lift and made a couple of decent DX contacts in Northern Ireland, The Isle of Man, Northumberland as well as Essex and Cambridge.
In a few weekends it is the National Hamfest, which is held in my home town and I hoping to pick up some bargain gear to improve my UHF set up, however from past experience that may prove difficult.

Friday, 5 September 2014

Repairing a Kenwood TR9500, Part1 - The Diagnosis

A fellow SKARS club member picked up a nice condition Kenwood/Trio TR9500 70cm all-mode transceiver (circa 1980) from the Hamfest last year for not a lot of money and he hoped to use it for the UKAC contests unfortunately it proved to be faulty.

From the description of the fault and studying a downloaded service manual I suspected a relatively simple fault and saw an opportunity to acquire it and offered to buy it for the price he had paid. However I have decided to be more charitable rather than mercenary and have offered to give it a look over and repair it for him if I can.

The fault as described was the rig receives okay but on transmit there was a carrier on FM with no audio and a very quiet SSB signal. A faulty microphone had been ruled out and someone had suggested a bad connection internally. Due to the compactness of the unit and the difficulty in dismantling no one had felt confident to attempt any further inspection. I wasn't so sure this was the issue so at the last meeting I picked up the rig and currently have it on the workbench.

The microphone signal is amplified with the microphone amplifier Q1 (2SC2240(GR)), which is commonly used for both SSB and FM transmission modes and is incorporated in the carrier unit (X50-1720-XX). The amplified signal is then fed to both the SSB and FM circuits.
Looking at the block diagram of the carrier unit and the above functional description in the service manual I suspected the microphone amplifier Q1 to be faulty.

I want to confirm the fault first and so I connected up a dummy load and RF power meter and using the FUNCube Dongle SDR I could observe and monitor the output signal. Sure enough on FM there was a nice carrier at 10W with very faint audio, on SSB there was a small visible signal again with very little modulation. Whistling, blowing and tapping of the microphone could be seen on the waterfall... just!

I connected a switch to the Morse key input and confirmed the rig transmitted in CW with no issue.

On the block diagram there is a switchable tone burst oscillator for repeater access and the output of this is joined to the output from the microphone amp. Encouragingly the tone burst can be clearly seen and heard in the transmission again pointing to an issue with the microphone amp.

To get to the carrier unit PCB it was a simple matter of removing the bottom cover. The PCB is held in a metal frame mounted with five screws and can be lifted out, as pictured above. But before I did that I checked the continuity to the microphone socket and the 8V supply to the amplifier circuit and both were fine (see diagram below)

The poor quality image from the scanned service manual shows the bottom of the carrier unit, this is the side of the PCB visible without needing to remove it. The microphone connector is in the top left, putting an oscilloscope on the microphone input (pin1) a signal was observed, however the output (pin8) had an almost identical signal with little or no amplification. Injecting a low level audio signal from the a generator on this pin could be seen and heard in the transmitted signal. This observation together with the tone burst seemed to confirm the other audio circuitry was functioning normally and the microphone amp wasn't.

Actually removing the carrier unit PCB proved a bit tricky as it has a number of small and very secure connectors with ageing and delicate wiring, but I did manage to extricate it and a visual inspection didn't show up any obvious issues such as broken tracks or joints.

This is the detail of the microphone amplifier section from the schematic. Using a meter I have checked the continuity of tracks and have checked all the resistors for shorts or open circuits and they all read the correct values. The capacitors all look okay and checking the signals either side of C3 the C7 coupling capacitors show they are functioning correctly. This left Q1 a 2SC2240(GR) transistor as the likely culprit and I have ordered a replacement which should arrive in the next few days. I am hoping this will make it spring back to life.

Wednesday, 3 September 2014

Logging and datamodes with PZTLog

Organisation isn’t one of my strengths and my logging of contacts has been pretty woeful. It consisted of a spiral bound note book full of various scrawls sometimes tabulated for contests but more often than not a free form mess. With good intentions I purchased a proper RSGB Deluxe log book months ago but that has remained pristine and has just become a handy band-plan look-up!

Until recently I had only made a small number of voice QSOs on HF and had entered those manually into the online eQSL, QRZ and HRDlog logbooks I maintain.  JT65 data mode logging was handled by the JT65HF program itself and for the UKAC and other VHF contests I have been using the MINOS logging program - all in all a bit of a mishmash.

Now my operating confidence has grown I am making more contacts and so I really need to computerise and centralise my logging. After  looking at a number of programs I opted to give Charlie Davy’s (M0PZT) freeware PZTLog a try and after using it for a couple of weeks I am very impressed.

The program has a multitude of features but at the moment I am using it to simply enter and log details of contacts, combined with the CAT interface to the FT857-D and the OMNIRIG control the mode, frequency, band and power settings are automatically populated.

The really nice selling point for me was the inbuilt data mode operation. I have tried PSK and RTTY before using other programs but I often found myself confused and intimidated by the interfaces and jargon.

PZTLog uses the MMVari engine to operate PSK/RTTY and it uses a familiar waterfall display. The TX/RX window and  QSO macros are easily accessible and I found the interface much more intuitive than other programs I have used. On installation, the macros are already populated and labelled sensibly and are easily editable. By double-clicking received text you can set Callsign, Locator, RST/Serial, Name/QTH quickly and with ease.

In a short time I have made a good number of PSK QSOs as well as a some RTTY contacts, even giving some points away in the fast paced SCC RTTY contest last weekend.

Importing and exporting of logs is very easy and it has inbuilt eQSL uploading, but at the moment I am having trouble making that work reliably but that I think is me rather than the program.

PSK is a great mode, running no more than 30W, often less I have made a number of nice DX contacts and countries including Argentina, Oman, Japan and the Dominican Republic.

Thanks to Charlie’s program I now have a better understanding of how the mode and QSO works so may try some of the more sophisticated programs, or I may just stick with PZTLog for a while. Check out Charlie's page for lots more interesting information as well as some very funny light hearted audio features poking fun at the hobby.

In other news the VHF UKAC contesting is improving. Last week I made a last minute decision to lower the pole and put up my homemade wooden 6m MOXON but glad I did. Conditions weren’t good but still made a respectable number of contacts but not a lot of distance. I’ve climbed to 30th place in the 50MHz low power AL section.
Last night was the 144MHz UKAC and what a great night it was, conditions were brilliant and it was very busy on the band. Still operating search and pounce mode I snagged just 32 contacts, but with 13 multipliers giving me by best score so far on that band.  Operating in the low power AL section as M6GTG it is hard work getting through the pile ups but it was great fun trying.
Finally I became a licensed ‘foundation level’ amateur a year ago this month (M6GTG), and have since become an ‘intermediate’ (2E0NRD) and have now taken the bold step of applying to take the ‘advanced’ examination next month. I say bold because I haven’t taken a course or studied for it per se but with my background and education I have covered most of the theory even if it was over 25 years ago – with a bit of serious reading, revision and dusting off of the memory banks over the next few weeks I hope to be ready!

Tuesday, 19 August 2014

Portable in a very windy Cumbria

Before amateur radio took over my life my main pastime was competing at dog agility which I did moderately successfully for many years, for several of those I was even the chairman of a Nottingham Agility Dog Training Club and organised one of the larger Kennel Club Championship shows as well as judging at many events. If you search my YouTube page there are a number of videos showing me and the dogs in action.

Things change and sadly I became disillusioned with the sport as seemingly endless rule changes and its increasing popularity saw it losing its core ideal, what was meant to be fun for dog and handler had sadly become too competitive, professional and commercial, too many people now make money out of the sport and what was once an enjoyable social activity is now spoilt by unsportsmanlike behaviour, complaints and bitchiness.

When my dog Boris suffered a cruciate injury the enforced time-out made me realise I didn't want to do it anymore and so I don't.. well apart from the odd exception, last weekend was the West Lakes Agility Club Show held in the small town of Haverigg on the Cumbria peninsula (Locator IO84IE)

This is a lovely old-style small friendly show with the bonus of being held just a stones throw from the sand dunes and beach. I had agreed to go and like the recent holiday in Skye it was initially planned with no thought for any radio operating.

We would be caravanning at the show for the best part of four days without any electrical hookup and the wife had volunteered to help on Saturday leaving me on my own for most of the day... so a plan was hatched at the last minute.

I purchased a nice new 'spare' 100A/h leisure battery and smuggled on board the FT-857D with some suitable battery clips, headphones, a fiberglass pole, some antennas. I don't own a suitable 'portable' ATU at present,  having borrowed one from SKARS on several occasions but as this was a last minute thing I would have to chance operating without it. I took the M0CVO HW-20P OCF-Dipole, which has a usable VSWR on 20m, 17m, 15m, 12m and 10m without an antenna tuner and the M0CVO Magitenna, but wasn't sure what I would get from this as I'd only ever used it with a ATU.

The weather was difficult all weekend, we arrived on the Friday to be met with warm and sunny conditions but a steady strong wind. There was bit of a battle to get the caravan awning up but we managed it.Saturday the wind just got stronger, the forecast for Sunday was for even stronger winds so it was dismantled and packed away, indeed it was worse around 25-30mph with must stronger gusts.

Undeterred I got the antennas up,  however the fiberglass pole I have must be getting on for 10 years old, and would often fly a pirate flag when camped at agility shows. It had already lost it's top section many moons ago but was still quite tall and so I hoisted up the OCFD balun and coax and the end of the magitenna wire in the buffeting wind and it was swinging around wildly - almost inevitably it proved too much and the remaining top section splintered!

Despite losing over in a metre in length I tried again and managed to get everything up, the OCFD wires were tied out to form a sort of inverted-vee using a handy nearby fence, the Magintenna was pulled to form a sloper across over the front of the caravan, but due to the lost height actually touched the front of the roof. Amazingly I got an almost 1:1 VSWR on 40m and loud and clear RX.    

This weekend was the International Lighthouse and Lightship Weekend (ILLW) this annual event has been going since 1995 and promote public awareness of lighthouses and lightships and their need for preservation and restoration, and at the same time to promote amateur radio and to foster International goodwill.

The bands were kind and I had an enjoyable Saturday afternoon and a few hours on Sunday making QSOs with a number of UK and European lighthouse stations on 40m and 20m and it seems the whole event was a great success. Alas the wind proved too much for the remainder of the fiberglass pole and it developed a large crack in the bottom section forcing me off the air.

By coincidence Haverigg has two lights, the old Hodbarrow beacon and the restored Hodbarrow Point lighthouse (pictured above from the beach). Last year we walked to the restored lighthouse but since the restoration was completed in 2004 it is sadly looking in need of some remedial work.

I only learned of the ILLW event at the last minute and sadly neither of the Haverigg lights were activated that weekend, next year if the show is on at the same time I may look at trying to operate from them.

Oh and the wind? Here is a video of a walk on the beach on the Sunday morning..

Friday, 8 August 2014

FUNCube-1 & FUNCube-2 Decoding Update

In the film "Willy Wonka and the Chocolate Factory" there is a scene where the lucky children (and parents) enter the "Land of Candy" where everything is edible and they run around grabbing a taste of everything. I am beginning to know how they felt.

Amateur radio has so many different things to try and over the last year I have found myself jumping around having a dabble at new things. Doing this and time being scarce has inevitably impacted the HAB payload and other Arduino projects. I have also neglected some of my previous satellite monitoring activities.

I had been regularly decoding the FUNCube-1 (AO-73) telemetry and uploading packets to the data warehouse (see earlier posts). To do this I had been using a discone in the loft and a FUNCube Dongle on the ageing main computer in the house.

This computer was on 24/7 but I couldn't leave the FUNCube dashboard running continually as the processor load would cause the noisy fans to kick in, besides for most of the day there wasn't a receivable pass. So I would just start up the dashboard when needed which meant remotely logging in from work. Due to an increasingly busy work load I would often forget or be unable to start it up and have got out of the habit. I therefore missed many opportunities to climb up the uploading ranking chart (it is really for the science honest!)

Of late there have been a large number of new satellites launched including the UKube-1 and the QB50 satellites which have modules and transponders as part of the FUNCube project.

Catching up with news after the holiday to Skye I noticed the announcement that an enhanced version of the FUNCube decoder dashboard has been released promising improved performance. The dashboard will also capture and upload (but not display) the FUNCube-2 telemetry transmitted from UKube-1

Looking at the FC1 upload ranking list I saw I had dropped down significantly and decided it wasn't acceptable!

As part of my antenna upgrade I have put up the X-50 dual-band collinear on the top of the pole feed with nice low loss RG213. This is currently connected to the FUNCube Dongle Pro+ dongle on the shack laptop, with the latest dashboard software installed.

It has been running 24/7 for the majority of the last week and has captured close to 2000 telemetry packets from FC1 a significant performance increase compared to my earlier set up, and I have now surpassed the 10,000 packet milestone (currently 11,626). I have also uploaded over 500 telemetry messages received from the FUNCube-2 on UKube-1. I have actually received more but a fault in the warehouse meant a lot were rejected due to a incorrect data field.

The FC2 subsystem on UKUBE-1 may not be enabled on every pass while the satellite is commissioned and the FUNCube team will be releasing an updated dashboard shortly for when it is operating full time.

At present both satellites are passing one after the other, with UKube-1 gradually gaining. So as FC1 goes LOS (loss of signal) UKube-1 rises elsewhere for AOS (acquisition of signal)

On one pass yesterday I thought I would capture some screen shots and show how I've got the dashboard set up for both payloads.

As already mentioned the existing dashboard can be used to receive both FUNCube-1 and 2, if using the FUNCube Dongle Pro+ by setting the central frequency to 145.905MHz and adjusting the upper and lower filter curtains both payloads can be received.

On the Orbitron prediction software you can see FC1  is overhead, with UKube-1 over the North pole.

The reception window on the dashboard is limited by moving the curtains. I have the lower one set at 145.906MHz just enough to filter out the centre SDR spike,  the upper one is at 145.945MHz. The telemetry signal on FC1 is at 145.935MHz but due to the Doppler effect the received frequency will vary above and below this nominal value, 10kHz either size is sufficient to compensate.

If you were just interested in one satellite you would move the lower curtain to around 10kHz below the nominal download frequency. However since UKube-1 is on 145.918MHz the lower curtain is set to below this again to compensate for the Doppler shift.

The resulting receive window will allow both to be received. However this does risks problems should QRM occur in the pass band as the decoder can lock on to this, luckily the improved dashboard software discriminates between the signal and noise much better than previous versions.

The dashboard below is receiving the FUNCube-1 signal (click to enlarge)

The data is being uploaded and checking the real time display on the warehouse confirms this (my old callsign M6GTG) however you might not show up every single time and the FUNCube-1 Flight Model tab must be chosen as seen below.

As the pass finishes and UKube-1/FC2 comes overhead and due to the omni-directional X-50 I don't need to change anything.

The dashboard soon detects the new signal at the lower frequency and begins decoding.

The received payload ID is shown in the bottom right of the dashboard

Again the upload can be confirmed by viewing the real time data page on the warehouse by selecting the UKube-1 FC2 Payload tab. It should be noted that it seems FC2 is sometime sending spurious data elements in the telemetry which the warehouse is rejecting so some uploads may not be displayed.

It is really that simple.