472/500kHz transceive transverter

Rev C Transverter (one correction: o/p LPF cap 6n8, not 100n)

Armed with the sensitivity data in the last post I have now modified my MF transverter to add the receive parts, without a preamp. I used the same scheme adopted in my old transverter to automatically switch through the 500kHz (or 472kHz) signal on receive directly to the FT817. Only 4 additional parts were needed to make it into a TX/RX transverter.  As proof that the RX part is working I have just copied PA0WMR with a huge signal on OPERA Op4 with the signal passing through the transverter.

How deaf is the FT817 at 136, 472 and 500kHz?

You may have read that the FT817 is deaf below 160m. This matters if you want to use the rig "as is" without preamps as a receiver for 136, 472 or 500kHz. So I decided to measure the performance using a signal generator. I measured the MDS on CW (the level at which I could just still hear a  CW tone without additional filtering), the level for S1, S5 and S9 on the FT817's meter. I also checked whether having the IPO switched in or out made a difference

These were my results:

136kHz (best results with IPO on)  DEAF!
MDS -103dBm
S1 -72dBm
S5 -68dBm
S9 -48dBm

472kHz (best results with IPO off)    SLIGHTLY DEAF
MDS  -120dBm
S1  -84dBm
S5 -81dBm
S9 -60dBm

500kHz (best results with IPO off)    A BIT DEAF

MDS  -124dBm
S1 -85dBm
S5 -82dBm
S9 -60dBm

What conclusions can be drawn? Well, the FT817 is definitely very deaf on 136kHz and needs a preamp to be usefully sensitive. On 472/500kHz, although the MDS is worse than at 1.8MHz, the sensitivity is arguably OK without a preamp. Yes, a small amount of high dynamic range gain with good filtering to stop overload from adjacent broadcast stations may give you a slightly better sensitivity, but the question is whether this matters when external noise may be the limitation. I have used to FT817 on 500kHz for several years and heard most of what was going, including transatlantic stations. At 472kHz it is slightly worse but still useable I think.

GQRP Component Data Book

Tony Fishpool G4WIF, G4CCQ, G3OOU and others have created an on-line, downloadable, GQRP Data Book which has the pin-outs of a number of devices commonly used in QRP designs featured in SPRAT and elsewhere. It is just what I need to stop me having to look up parts on the internet every time. This is "a work in progress" as they say with updates and additions coming frequently.

Finally, why not join the GQRP Club? Its quarterly magazine SPRAT is still the best amateur magazine in the world and remarkable value at £6 UK, 12 euros or $18 US. Details at http://www.gqrp.com/join.htm .  As well as very interesting constructional projects, the magazine has operating news, useful adverts from QRP suppliers as well as adverts for GQRP club sales which supplies members with useful QRP parts (semiconductors, crystals, DVDs of SPRAT back issues, etc) at very reasonable prices. The GQRP club represents the spirit and ethos of amateur radio at its best.

472/500kHz TX transverter - first schematic

10W 472/500kHz TX Transverter (CW, WSPR, OPERA, QRSS)

OK, here is the first schematic (subject to corrections, changes and improvements) of my simple TX transverter for 472 or 500kHz. This one needs no expensive parts and went together painlessly. The PA filter parts used the GW3UEP approach of winding thickish copper wire (1mm in my case) onto 22mm white PVC drain pipe pieces. The mixer, LO and squarer stage all use ubiquitous 2N3904 transistors (my favorite!) and the PA a cheap IRF510 FET that produces 10W RF without even getting warm.

Next stage is to add the RX preamp and filter and sort out RX-TX switching. I also want to try to go for a higher PA output power which will require changes to the output network.

500kHz tranverter (Mk 2) breadboarding

This weekend I've made considerable progress with the new transverter for 472 and 500kHz and fully breadboarded a 10W TX transverter.

My objectives are to make the design simpler than the original 2010 design  (no expensive SBL1 double balanced mixer!), produce more power and improve the RX performance. Also I want to reduce the need for special parts such as toroids.

The design evolving is, like all my designs, a mixture of my own ideas and the best from other people. When the design is ready I will put it here and on my main website. I've moved away from 28MHz IF (too high, too much start-up drift) and instead gone to 3.7MHz using a 3.2MHz crystal available from GQRP inexpensively. The TX mixer (none is needed on RX as it is uses the FT817 in split mode receiving directly on MF) is a simple bipolar stage followed by a low pass filter. For the PA I have largely copied GW3UEP's excellent designs for a 25 (and later 100W) amplifier. Initially I am using an IRF510 from 13.8V and getting around 10W RF out. The next stage is to look at the RX front end. I want a little gain ahead of the FT817 but with good large signal handling and decent filtering. The FT817 works OK at 500kHz but is a little deaf.

So, a satisfying few hours building.

QRP semiconductor pin-out sheet?

Is it just me or do you also have to search the web quite frequently to confirm the pin-outs of devices you've used time and time again?  I need to do this for LM386, 2N3819, IRF510 and the 2N3904/6 almost every time I get them out of the drawers just to be sure. "Senior moments" I hear you say!

Does anyone know of a simple (all in one place) "crib sheet" that I could download giving the pin-outs of the common devices we frequently use in QRP projects?

500kHz WSPR

I left my 500kHz WSPR station running overnight last evening to see what reports I got. People are now generally using 500kHz USB dial for WSPR so that simultaneous monitoring on RX of both OPERA and WSPR is possible. Personally I can't tell much difference.

500kHz WSPR reports earlier (20mW ERP)

Anyway, my best reports were from F59706 (560km) and F5NWK (559km) when I was running around 15-20mW ERP from my current transverter and antenna.

My first ever website - 1996

Looking on the internet today I found an old link to my first ever website that I created in 1996. I'd forgotten the URL, so I put it into the Wayback Machine to see if it had been crawled and stored. It had. Created in Nov 1996, this was a snapshot of the site in 1997. See http://web.archive.org/web/19970328203144/http://www.lapr.demon.co.uk/ .  Actually, for the tools available then, it wasn't a bad effort as I think the page was created in raw HTML.

FT817 speech processor - English translation

Dave G3YMC kindly did an approximate translation of the German instructions for the Funk Amateur speech processor that I built at the weekend. This may be of use to others building this kit. Dave says this is not a precise translation and does not want to be held responsible if he has made any mistakes!

Incidentally on a local SSB contact with G3KKD this evening I switched from "processor out" to "processor in" and Ian said it nearly blew his head off, so it works, HI.

G3XBM Shack - 1977 style

My shack in 1977. I still use the same Morse key.

Just came across this picture of my shack in 1977. On the left is the Eddystone EC10 receiver. Next to it is a crystal controlled CW transmitter for 28MHz and a down-converter to 4-6MHz IF, tuned on the EC10. On the far right is the Belcom Liner-2 2m SSB transceiver, a state-of-the-art rig at the time. The boy in the chair is my son aged 2 at the time. These days he is a successful professional jazz musician. I never did interest him or his younger brother in amateur radio.

More countries on 472kHz

Last night I left my 472kHz WSPR system running through the night and was very pleased to receive SM6BHZ and DF6NM at good S/N at times.

477kHz WSPR DX last night

FT817 speech processor built and working - brilliantly!

DYC-8x7 speech processor tucked under the FT817

This morning I built the Funk Amateur DYC-8x7 speech processor kit that came last week. Total assembly time, taking it slowly, was just 30 minutes with no problems at all. Testing and set-up was easy in the end and the results so far are spectacular.

VHF NFD is running - I'd forgotten this - so this is an ideal time to test the rig with the processor in circuit. Using just my 10m halo - feeder loss is such that it is a good match, if not an efficient antenna, on both 2m and 70cm! - I went on and gave a few points away on 2m and 70cms. Whereas before I would be struggling, contacts came easily. The little speech processor makes a LOT of difference and is an excellent product.

Conclusion: at 34 euros delivered to the UK this represents excellent value for such an effective product.

FT817 speech compressor kit arrives

My Funkamateur BX-8x7 audio speech compressor kit (also known as the DYC-8x7) has now arrived. I was impressed by the speed of delivery and the packaging. The kit looks ideal and straightforward to build. One problem with this design was the RJ45 connector lead, but the latest version has 2 RJ45 sockets already fitted on the module and a ready made lead (with plugs on) to connect between the unit and the FT817. The MH-31 mic simply plugs into the other socket. The actual building should only take about 20-30 minutes.

My only difficulty is in the instructions which is a copy of the original Funk Amateur article  in German. I am hoping someone can translate this for me, or give me a precis with setting up instructions.

Ceramic filters on 472-479kHz?

An eBay seller from Hong Kong has 100 off 472kHz DIP ceramic filters on sale for £5.31 delivered to the UK. See item number 400305093888.

Some filters similar to this have useful bandpass characteristics and acceptably low insertion loss (around 3dB), so may be seriously useful for 472-479kHz rigs and transverters. For example, as a roofing filter to protect a RX after a small gain stage, or as a filter to clean up the output of a transverter at low level before applying a signal to a driver and PA. I guess they must also be useful in a ceramic stabilised oscillator.  Anyone used these in similar applications?

WSPR on the new 472-479kHz band

For the first time I've been monitoring 477kHz USB dial for WSPR signals, hoping to copy some of the Germans now allocated the band. SM6BHZ is on too, but not yet seen.

At 2058z DF0WD was copied at -27dB S/N for my first German WSPR signal on 477kHz at a distance of 556km. I have also heard a couple of other stations from elsewhere in W.Europe who appear to be testing at very low power before the band is officially released in their countries.

500kHz WSPR and OPERA compared

Today I've been comparing OPERA OP4 and WSPR performance by running my QRP beacon in daylight in both modes for several hours each on 500kHz. Theoretically OP4 should outperform WSPR by a few dB, but I am getting roughly similar reports from stations 126 and 210 km away in both modes.

Personally I prefer WSPR because of the neater on-line reporting system and user interface, shorter TX period (2 mins rather than 4 mins) and the fact that more data is being transmitted (call, power, location). Unfortunately only a couple of UK stations have been looking for my 500kHz WSPR signals, so the test is a bit limited.

SAQ VLF tests today

SAQ, the very old alternator TX on 17.2kHz VLF, was transmitting today and was copied as far away a North America. Here are some recordings made in Germany by Stefan DK7FC.

Dear VLF group,

Today the S/N of SAQ was much weaker here in Heidelberg/JN49IK, probably due to the high QRN levels.

I extracted a wav file containing the full message and tests. Can be used for reprocessing if of interest for someone: https://dl.dropbox.com/u/19882028/VLF/SAQ/SAQ_afternoon01Jul2012.WAV (117 MB)

And here is a mp3 file for listening in a normal player (first 2/3 is a test procedure, then the mesage comes): https://dl.dropbox.com/u/19882028/VLF/SAQ/SAQ_afternoon01Jul2012.mp3 (24 MB)

73, Stefan/DK7FC

MF bands and local comms

This morning with my 20mW ERP on 500kHz I worked G3XIZ around 45km away on CW. Chris gave me 569 (on his meter) when using his loop antenna on RX. He was a very good signal here. Earlier I copied the other stations in his net M0JXM and G3DXZ. Yesterday G3KEV was a good CW signal and PA0A was copied later today.

500kHz QRP transverter with ferrite rod ATU on bench

The new 472-479kHz will be an ideal band for local area CW nets: as my far less than ideal set-up here proves, one can work up to around 45-50km without any problem even with very low ERPs. Running 6dB more power from the PA (I currently have just 5W out) will help further.

This afternoon my 500kHz OPERA has reached yet another new station: G8ALS in Coventry 126km away. My maximum daytime range on OPERA OP4 mode seems to be around 220km, although a few more stations reporting may increase this.

500kHz ERP

Using the coax feed to my 10m/6m halo as a vertical I've worked out the ERP currently on 500kHz OPERA. The RF power from the transverter is around 5W from an IRF510.

The 10m and 6m halo lengths correspond to a horizontal capacitance of around 35pF. Some of the feed from the shack to the bottom of the vertical section is horizontal through the loft and this has not been included (I think it may add loss though). The vertical section outside is 6m long, equivalent to a vertical capacitance of 36pF. Using standard formula this means my effective height is around 4.48m.

Radiation resistance then works out as 0.088 ohms.

Measured antenna current is 0.48A (using a current transformer and detector)

ERP = 0.48 x0.48 x 0.088 = 20mW (or lower if the losses are higher).


 

First 500kHz OPERA reports

Having managed to match my 6m long coax feed line (as a Marconi vertical) up to the 10/6m halo antenna on 500kHz by adding some inductance wound on a ferrite rod in the shack, I've just received my first OPERA beacon reports on the band from ON6EO at a distance of 220km and G0KTN at 210km. Reports were -30dB and -29dB S/N which is marginal.

OPERA mode on 500kHz

500kHz OPERA RX this afternoon (on left are my spots)

Having now uploaded the latest version of OPERA weak signal mode software I have been looking on 500kHz using my, as yet, untuned short vertical antenna. CPU load without waterfall is running at around 40-50% on my Dell Inspiron 630m and the PC is running in a stable way. So far copied PA0A, PA3ABK and M0FMT. If I can get the antenna resonated crudely I may try OPERA TX on 500kHz later this weekend.

10m ROS16 QSO

ROS16 10m QSO this morning: my first for some time

The last time I tried ROS and OPERA on my PC it reacted badly and crashed so I'd been reluctant to try the mode again in a hurry. However, today I loaded v7.0.9 which runs OK when the waterfall is deselected on my 6 year old Dell Inspiron 630m with 1GB RAM and a 1.73GHz Intel M processor.  As an initial test I ran 5W on 28.185MHz and managed to answer a CQ call from DK6SQ who reported me at -13dB S/N.

Denmark active on 472-479kHz band

In the last few days OZ amateurs have been granted access to the new band. Along with Monaco and Germany there are now 3 countries (to my knowledge) allowed to use this new LF band. It has been confirmed that The Netherlands will get access on Jan 1st 2013.

VLF amateur activity

There is a new VLF grabber at Darmstadt Germany that may be useful for 8.97kHz tests. It is at http://skmail.ikp.physik.tu-darmstadt.de/gvw/grabber.html. The grabber is primarliy there for VLF research into earthquake precursors.

Stefan DK7FC reports that the permit he has to use a 300m kite antenna expires soon, so he may try a further soon before that date.  Chris G3XIZ is still hoping to resume VLF tests once a new loading coil is wound. He is looking for a suitable (very long!) source of PVC covered wire.

DYC-8x7 speech processor kit

Funk Amateur, the German magazine's online shop is selling (after a gap I believe) a neat in-line speech processor kit for the FT817 and similar Yaesu rigs called the DYC-8x7. On http://www.eham.net/reviews/detail/2546 it gets good reviews.

I'd like to order one but cannot understand how to go about it not being a German speaker. Google translate doesn't translate all the words, so I am stuck. If anyone can help I'd appreciate it, or tell me if it is available in the UK.

See http://www.box73.de/product_info.php?products_id=945 .

LATER UPDATE
With a step by step translation using Google Translate I managed to register on the Funk Amateur site and place an order.

On-line CW training at LCWO

Typical LWCO log-on page

If you are like me then your CW skills are not the world's best. Even though I am a G3 and licensed since 1967 my CW really is pretty pathetic. On an HF QSO when exchanging callsigns, reports, and serial numbers I'm usually OK, but when ragchewing with seriously good CW operators I'm embarrassed by the amount I miss. Some operators are very good and slow down, but not everyone.

However, for we CW duffers, help is at hand: http://lcwo.net/ is a rather superb on-line CW training facility that I believe could really help improve CW skills with a few minutes' effort each night. I have been to the site before and managed to improve my speed a bit but need to return there and try some more. All sorts of CW training is available at all sorts of speeds. If you want to use CW, which is an excellent mode especially for QRP, then this is worth a visit.

Ultimate QRSS/WSPR kit from Hans Summers

Hans Summers G0UPL has just announced a wonderful new kit. Amongst other modes it also supports stand-alone WSPR beaconing when used with a GPS timing reference, without a PC. This was his announcement on the GQRP Yahoo group earlier today:

All,

This is to announce a new standalone QRSS/WSPR kit by Steve G0XAR and Hans G0UPL. The kit supports WSPR, QRSS, DFCW, FSK/CW, CW, Hell (full speed and half-speed), Slow Hell, and customisable FSK patterns. The WSPR encoding is on-chip. It supports the connection of a GPS module for frequency locking, accurate time, and location (for WSPR). Power output is measured at 185mW on the 30m version. We are selling versions for 30/40/80m and perhaps later 20m and 160m. It does not require a PC, it has an LCD and two buttons to control it.

The price is GBP 15.39 (EUR 19 or US $24 approximately) plus shipping.

You can see all the details here: http://www.hanssummers.com/qrsskitmm and order online at http://www.hanssummers.com/shop . We expect to be shipping by 27-29 June.

The kit supports the following modes:

+ QRSS mode (plain on/off keyed slow CW)
+ FSK/CW mode (frequency shift keyed slow CW)
+ DFCW mode (dual frequency CW, dit's and dah's on different frequencies)
+ WSPR mode (Weak Signal Propagation Reporter)
+ Slow-Hellschreiber (frequency shifted slow Hellschreiber)
+ Hellshreiber (full-speed standard Hellschreiber, and half-speed Hellshreiber)
+ CW (plain CW)
+ Customisable FSK patterns

Other features:

+ 24-character LCD + two-button user interface
+ User-programmable (callsign, message, speed, FSK, mode, etc.), settings stored in EEPROM
+ GPS interface, for locking the frequency in slow-speed modes
+ On-chip generation of WSPR encoded message (no PC required)
+ WSPR maidenhead locator can be generated from GPS-derived latitude/longitude
+ Selectable “frame” size, for stacked QRSS reception
+ Plain CW callsign identifier at selectable interval
+ Produces 150mW RF output, or AF output for driving an SSB transceiver
+ Higher output power by additional PA transistor and/or higher PA supply voltage

73 Hans G0UPL and Steve G0XAR

6m WSPR and Doppler shift

Note Doppler on signals at 1742z

This evening some very strong signals have been coming in from North Africa on 6m by Es. CN8LI has been coming through on WSPR for a few hours with some people receiving him at +12dB S/N. What is interesting is the amount of Doppler on his signal at times. Also, several other signals coming through with up to 40Hz of shift over the 2 minute WSPR slot making decoding impossible. Some of this will be aircraft reflection, but some may be due to fast moving layers of ionisation in the E layer. At least with the WSPR screen such effects can be seen.

Digital QST

Although not (yet) an ARRL member I am tempted join to get the new digital version of QST magazine. A sample of this new digital version is available from the ARRL website.

QST has been a very useful source of data going back to around 1916. I well remember thumbing through the copy in Plymouth library when attending  RAE lessons at Plymouth Tech way back in 1966.

Rigol test equipment

The Rigol Spectrum analyser at £895 plus VAT

In recent weeks I've seen several adverts on the ARRL website (I had a 30 day free trial) for test equipment made by a company called Rigol. In the UK they sell a well specified spectrum analyser for £895 plus VAT, which looks an incredible bargain for such an instrument. They also do a range of other pieces of test equipment such as scopes, waveform generators and power supplies. Although £895 is a bit out of my price range, I wonder if anyone reading this has any experience of this supplier's kit? If so, what is it like in terms of quality and reliability? If one was running a small RF design business one could set up a small, well equipped lab for a few thousand pounds with all new gear from this supplier. How do they do it?

SAQ transmission on 17.2kHz on July 1st

From the SAQ website:

Transmissions on Alexanderson Day
We plan for transmissions on Alexanderson Day Sunday 1st July. If we are allowed to use the antenna we start the machine transmitter at 8.30 UTC and a message is sent at 9.00 UTC. Second start of the transmitter at 11.30 UTC and a message is sent at 12.00 UTC. The frequency is 17.2 kHz CW.

 QSL-reports are kindly received:

 QSL reports can be given via:

- E-mail to: info@alexander.n.se

- or fax to: +46-340-674195

- or via SM bureau

- or direct by mail to: Alexander - Grimeton Veteranradios Vaenner, Radiostationen, Grimeton 72, S-432 98 Grimeton, SWEDEN

Note: SAQ is a member of the Swedish Amateur Association (SSA) and "QSL via bureau" is OK.

ISS Flash Project

Guido PE1NNZ has sent me this interesting link about a recent experiment with the International Space Station using optical frequencies. See http://www.cqdx.ru/ham/ham_radio/iss-flash-project/ .

Back home again and the 472kHz transverter

Icefield Parkway, Alberta

After nearly a couple of astounding weeks in British Columbia and Alberta, Canada my wife and I are now back home. The scenery and wildlife were just amazing, especially the bears like the one below seen just a few metres away from us.  Although I only managed about an hour of shallow sleep on the plane back from Calgary last night I decided it was better to fight the jet-lag and get on with some chores rather than crash out and wake at 2am tomorrow.

One of the 8 black bears we encountered - this one VERY closely

Once the lawns have been trimmed and the hedge cut, I've decided to crack on with the design of a new transverter for 472-479kHz as the next project. Already there is activity from Germany and there are a number of NDB beacons to allow the receiver part to be checked. Jan 1st 2013 (the likely date of release in the UK) will arrive far too soon.

I am trying to decide on the choice of IF as I want to use an unmodified FT817. 28MHz will allow 472-479kHz to appear "in-band", but at 28MHz the start-up drift as the LO settles will still be some tens of Hertz. This hasn't proved problematic with WSPR, so guess this is my choice. At least the dial will directly read the "right" frequency e.g. 28.477kHz will correspond to 477kHz.

In view of the picture above, I am not sure what power the transverter will use bear-foot (sorry, weak joke).

Knife Edge Refraction at VHF

Currently I am sitting in a log cabin (with a log fire) surrounded by snow capped mountain peaks wondering how 2m propagation would be from here. Sharp mountains often allow good propagation into screened valleys by refraction over the peaks sometimes with strong signals. Unfortunately I have no ham gear (apart from Echolink) to try it. Instead I am just enjoying the views. 10cm snow forecast tomorrow here, HI.

Canadian Rockies

For the last few days I've been in the Canadian Rockies. The scenery is truly the very best I've seen (inland) anywhere on Earth. The 300km drive today from Banff to Jasper had snow capped mountains and azure blue lakes and rivers all the way. Only seen 1 HF antenna so far and that was from the Rocky Mountaineer train from Vancouver to Banff.

Germany gets 472-479kHz

Surprisingly, news on the wires today that German amateurs have been granted early access to the new MF allocation. I wonder if OFCOM will release it early too?

"LF Today" RSGB book on special offer

This excellent introduction to LF/MF amateur radio is available from the RSGB bookshop at just £7.99 and I can recommend it. It helped me a lot when I started and still gets referred to regularly.

CW on 136kHz

Mike G3XDV reported normal speed CW activity on 136kHz with QSOs with G3KEV and DK7FC's normal speed CW beacon. Although harder work with QRP, 136kHz is an ideal band for CW contacts. A lot of people are saddened that digital weak signal modes have rather put CW on the shelf.

VE7 Repeaters

Now 23 hours without sleep having arrived in Vancouver after a long flight from the UK. Currently in the hotel room trying to work some BC locals via Echolink connected repeaters. What I really need is SLEEP though!

First country gets 472kHz allocation

Monaco is reported (by 3A2LF) to have allocated the 472-479kHz band to radio amateurs from May 18th as a secondary allocation with a maximum power of 1W EIRP. Others are likely to follow in the following 12 months, we hope.