Another 472/500kHz transverter built stateside

Just got this nice email from John WA3ETD/WG2XKA who has successfully built another copy of my 472/500kHz transverter.

"Hi Roger,

I completed your design XVTR Saturday here, on the air on WSPR last evening had eight uniques and flawless operation.

I slightly modified the PA by adding the gate resistor and diode, as well as driving the FET via a cap. I only had surface mount IRF-510, that is the raised, floating copper heatsink that sits on two tiny standoffs at drain potential.

Thanks again for publishing your design!  PIX attached.

73,
John WA3ETD / WG2XKA"

WG2XKA's version on my 472/500kHz transverter

Rotatable dipole or HF halo?

DES Rotating Dipole

A new antenna is being advertised by InnovAntennas: a compact rotatable 15, 10 and 6m dipole with droopy ends so that the overall length is no greater than a single 10m dipole. It is called the DES-Rotating Dipole. The image on the right (from the InnovAntenna website)  shows the neat arrangement which can be fed directly from 50ohms. Without lossy traps the power rating is at least 5kW, rather more than I would ever need.

Now, neat though this is, I question whether it is really worth the expense. At this stage I have no idea of price but I would expect somewhere between £50-100? My simple Homebase-10 wire halo is MUCH smaller because the 10m dipole is arranged in a square. A 6m halo can be nested inside very easily and fed with the same coax. To add a 15m halo would only increase the size by 50%. Unlike the Cobweb antenna, my simple design could be assembled as a 3 band version for less than £15 with all new parts.

Homebase-10 10m halo

How much down is the halo compared with the nested dipole?  In most directions, apart from a tiny segment in the direction where the ends of the halo meet, less than 2dB. What is that in S-points? Hardly noticeable at all at about 1/3 of 1 S-point.

A dipole, if rotated, does have the advantage of being able to null out interference but I am not sure this is such a benefit. For me, it is either something like a horizontal halo which tends to be a "quiet" antenna picking up little local (vertically polarised) man-made interference or a small beam which would have some gain and directivity. However, the latter will only add about 0.5-1 S-point in signal level and, time you buy a decent rotator and the beam, you will have paid 10-15 times more for the privilege. A beam does add directivity and interference rejection, but is much larger. For me it is a "no brainer".  My simple little halo has allowed me to get QRP reports on SSB, CW and WSPR from all over the world. It is simple and works well.

Lesser Chirpy reaches Cyprus

No QSOs this morning yet but a RBN report from 5B4AGN in Cyprus with the 80mW lesser Chirpy 10m CW transceiver to the Homebase-10 halo. This is the first time I've looked for RBN reports with this tiny transceiver.

Reverse Beacon Network report for 80mW Lesser Chirpy

When I got back from my grandson's birthday party in London in the late afternoon I put out about 10 CQs on 28.060MHz with the rig, but no QSOs or RBN reports. I shall try again during the week.

Ten-Tec Argonaut VI - has it died?

The Ten-Tec website still has no information whatsoever (that I could find) about the Argonaut VI which was supposed to be ready to order by now. I'm wondering if, despite talk of pilot runs and the like, Ten-Tec has had second thoughts and decided not to release it after all.  I've just written to Ten-Tec to find out what the news is. I've asked when it will be available and at what price. We'll see what comes back from the sales team.

Solar prediction update

NASA has slightly modified its predictions for the current sunspot peak showing the peak month as May 2013 with a 95% prediction of just over 100. The smoothed number will peak later.  Although conditions will gradually deteriorate after the peak, the monthly sunspot number is still expected to be over 60 right until mid 2016. See http://solarscience.msfc.nasa.gov/images/ssn_predict.txt . The evidence in the short- term looks somewhat less good, but things can change rapidly.

So, get on the air, especially on the higher HF bands and enjoy the good times!

Date/Month 95%   50%     5%

2012  11  96.1  68.7  41.4
2012  12  97.2  69.7  42.1
2013   1  98.2  70.5  42.8
2013   2  99.1  71.2  43.4
2013   3  99.8  71.8  43.9
2013   4 100.4  72.4  44.3
2013   5 100.9  72.8  44.6
2013   6 101.3  73.1  44.9
2013   7 101.6  73.4  45.1
2013   8 101.8  73.5  45.2
2013   9 101.8  73.5  45.2
2013  10 101.8  73.5  45.2
2013  11 101.6  73.3  45.1
2013  12 101.3  73.1  44.9
2014   1 100.9  72.8  44.6
2014   2 100.4  72.4  44.3 

Delay getting 472-479kHz released in the UK?

On the GQRP Yahoo group today Colin, G8FRA/M5FRA, posted this message regarding the release of the new 472-479kHz band in the UK. If his information is correct, there could be some delay in the bulk of UK amateurs gaining access to the new MF band. This would be a great pity.

"Roger,

From what I learned by talking to a couple of people at Newark (RSGB and OFCOM) we will not get the new allocation in Jan 2013. Those with existing SRPs will have them changed to remove 500kHz and add 472-479kHz. I asked when applications would reopen and there was no date for that. Evidently OFCOM have to consult before there can be any changes to the license schedule and have been too busy with the Olympics to make any progress on that. I did suggest that the RSGB should come clean as anybody who has spent time and money on new equipment might just be a bit disappointed.

Colin - G8FRA/M5FRA
m5fra.org.uk"

If this information is correct, then why is our national society, the RSGB, not making this public? I have written to OFCOM and the RSGB asking for more concrete information.

10m Lesser Chirpy in a new box

Lesser Chirpy (should be No Chirpy!) 10m transceiver

At last I've got around to putting my Lesser Chirpy ultra simple 28MHz CW transceiver in a case. I've added an extra switch so I can listen on another RX if conditions are such that the internal RX struggles, although even with my 64 year old ears I can clearly hear better than -100dBm signals on Lesser Chirpy. Offset is set at about 700Hz between RX and TX. The FSK keying is a bit odd - there is only around 100Hz shift between carrier on and pseudo off (i.e. shifted) but there is zero chirp. This is now a seriously useful transceiver, albeit very very simple. Power out on this sample is around 80mW, so I believe this is certain to span the Atlantic in the next few days, if only to be spotted on the Reverse Beacon Network.

Lesser Chirpy cased

I have not got an internal low pass filter on this model. One should be added between the rig and the antenna to ensure low 2nd and 3rd harmonic levels.

Ferrite Rod RX antenna for 472kHz

 In an attempt to overcome my high LF noise level, today I made a small ferrite rod antenna and preamp for 472kHz which I've been trying out on RX. The ferrite rod was just a small 10mm diameter 60mm long rod (i.e. it is a small ferrite rod) tuned with a 365p variable capacitor and fed into an MPF102 gate at high impedance with the output fed to the FT817 via an emitter follower. At the moment the rod is sitting on the bed in the shack. Despite this, it is picking up WSPR from DK7FC.

I shall have to try a larger ferrite rod next and try placing this remotely in the garden away from noise sources. For a first attempt this is encouraging.

The prototype used to receive DK7FC and G3ZJO

UPDATE: later I tried the 60mm ferrite rod and preamp on 500kHz and copied G3ZJO on several occasions. 

MF "swish, swish, swish" interference

In recent months I've been suffering from man-made noise on MF which was not there before. I've a constant S8 noise floor now (it was around S1-2 before) and as I tune from 300-500kHz I get a rapid  "swish swish swish" every few hundred Hertz. I think there are frequencies where it is stronger but the new 472-479kHz is BAD, although I still manage WSPR decodes from DK and SM. For CW it would be just about impossible.

Now, I haven't yet tried to systematically work out what this is yet and nor have I tried a small external loop on RX or an E-field probe down the garden.

Before I start to investigate, does anyone have a clear idea what this rapid "swish swish swish" QRM is likely to be? I don't think the source is in my own house and on one side the neighbour's house is currently unoccupied. I have tried the obvious (turning off lights and SMPSUs in my own place) with no success.

Any knowledgeable help would be much appreciated.

Man-made interference at MF and LF is a critical consideration for newcomers. I hope that a new version of the RSGB book "LF-Today" (if one is planned) will give some information on how to search out such sources and some strategies for how they might be mitigated.

Building requests

In the last 24 hours I've had a couple of requests from people asking me if I'd build some of my projects for them. One person asked if I'd build them a Pipit 15m transceiver and another a 472kHz transverter. Regretfully I had to say sorry that I could not.

It is not that I don't want to. Rather, it is because I don't have enough spare time! I've so many projects on the go currently, and a stack more in my head waiting to get started, as well as trying to live a normal family life doing the usual chores. Then we have the grandchildren who take time, not that we mind this at all.  So, please do not ask if I can build projects for you. I always try to help with advice and suggestions when asked - I try to respond within 24 hours unless I am away -  but I do not want to do building.

Quite a few of my projects would benefit from a small PCB. This is also something that I rarely get around to because I've already moved on to something else. There is probably a small business possible, if I was inclined, designing projects, making a PCB and selling kits. This is unlikely ever to make me rich though and I'd prefer to be a source of ideas instead.

Norway on 4m

The Norwegian authorities have granted further access to parts of the 4m band (70.1875 - 70.2625MHz), with some regional limitations. This is great news for 4m where more and more countries are now gaining access. The following chart on the Four Metres Website (I've linked to it here) shows the countries with 4m allocations currently.

Norway gets 472-479kHz right away

Norway has been granted immediate access to the new MF band with CW and all digital modes permitted. See  https://www.nrrl.no/318-news/latest-news/492-lb1g .  I hope some LA stations come on to WSPR in the new band this evening.

More 474.2kHz WSPR

This evening I am copying 3 stations, so far, on 474.2kHz USB dial WSPR: SM6BHZ and DK7FC are both good signals with QSB but I've also copied DL3ZID at -27dB S/N. QSB is slow and it takes about 12 minutes for DK7FC's signal to go from -27dB S/N to -12dB S/N.

Lesser Chirpy 10m transceiver

You may recall that some months back I did a tiny transceiver for 10m CW ....that chirped. Well, this is the latest version that does NOT chirp! Instead of keying the oscillator current, I now key the capacitor that sets the oscillator frequency instead i.e. FSK keying. The latest version is shown here. Have a go: 10m is is good shape and you may get a few QSOs.

If the going gets tough (the RX audio level is low!) try adding an extra antenna change-over switch so you can receive on an external receiver instead. or add a 100n from TR2 collector and feed the signal into a sound card and SDR so you can use the PC's audio gain to help with copy and tune either side a few kHz.

472kHz transverter (rev K)

Several people have now built versions of my 472/500kHz transverter. The latest version is shown below which includes provision for an additional low pass filter when using a fairly long (less sharply tuned) antenna. Although some capacitors could be combined to reduce the component count, I've shown it using readily available high voltage capacitors. The 16uH inductors are 43turns of 0.71mm wire on 22mm white PVC pipe.

In the last few minutes I've been looking on 472kHz WSPR and see that SM6BHZ and DK7FC are coming through OK despite my S8 noise floor.

SM6BHZ and DK7FC this afternoon on 472kHz WSPR

December's Practical Wireless

The December 2012 edition of "Practical Wireless" has my article about the 2m AM Fredbox and the 6m AM Sixbox transceivers that are described in more detail on my website. These simple QRP VHF transceivers proved to me that you don't need to spend lots of money to make simple transceivers that work. Both have produce interesting QSOs: the 2m Fredbox had several 90km QSOs with one at 160km, despite being only 10mW output and using just a whip antenna!

Today there is not that much AM activity on the bands but I think this is a great pity as the mode has a lot to offer. I do hope the RSGB can be (eventually) persuaded to add 144.55MHz as the AM calling/working frequency in the band plan. It is mentioned (almost lost) in the foot notes, but it needs to be properly shown. For some reason the RSGB seems to have a problem with 2m AM.

I hope others will build simple AM gear for 144.55MHz or crystal up some ex-commercial PMR radios and again enjoy the fun of 2m AM. Second hand AM gear for 4m and 2m can often be obtained for just a few pounds as no-one wants it.

GPS Route Logger

Last week I bought a Ventus G730 GPS Route Logger from Martin Lynch for £34.95. Today I tried it out for the first time on a walk in the bright autumn sunshine at Ickworth park, near Bury St Edmunds. I am totally delighted with it.

The map below shows the route taken as plotted on Google Earth. The data that comes out of the logger shows route taken, speed (average and instantaneous) , distance traveled, and altitude up and down. If linked to a digital camera file it can be used to geotag photos on a walk. I am very impressed that something this small shoved in your pocket can produce such fun results. I now need to find a use for this in my amateur radio experiments.

Google Earth plot of a walk today using data from the Ventus GPS logger

500kHz WSPR tonight

My last post with this title got corrupted when I tried to edit it, so this is a shortened revised version. 500kHz WSPR this evening has been very good. In the last couple of hours I've been getting 8-9 reports with each transmission slot when running less than 50mW ERP. Best DX 707km to DG3LV.

500kHz WSPR reports this evening

I've downloaded the latest version of JT9 software and hope to try this for 2-way QSOs later this week on 500kHz. My current problem is the S8 noise floor which I hope to reduce by using a better sited E-field probe or loop antenna (for RX only) further away from the house.

There are still plenty of CW stations on 500kHz. One evening last week I had a very enjoyable CW QSO on the band with G3XIZ. Semi-locally there are around 3-4 stations on a regular Sunday morning 500kHz CW net.

Projects pause

This week I am having a bit of a rest from amateur radio. We have two of our little grandchildren staying with us until Sunday and they take top priority. Anyway, one sleeps in my bedroom shack!  So it is off to ride on toy tractors, eating some cakes in a cafe and help Grampy deliver poppies.

With the XYL and grandchildren

There are some geomagnetic storms around so HF conditions are unlikely to be very good for operating.

Next week should see me back in action. My first task is to make some changes to the 472/500kHz transverter - adding an additional filter as shown in the Rev H schematic on my website so that it meets FCC requirements before an article on the small transverter appears in QST magazine next year all being well. It has been accepted. I've also got to update the schematic and parts list.

Next on the list is probably to get my 10m halo down for its rebuild that didn't get done last week. Then I am in to several possibilities including getting "Lesser Chirpy" going on air (the chirp free version of Chirpy) and casing it up. Also, there is the 481THz NLOS beacon with those BIG powerful LEDs I bought a month or so ago. There is also a new 136kHz transverter (like the 472kHz design but for 136kHz instead). And then there are all sorts of other ideas floating around in my head which probably won't get done for another year. These include a simple Fredbox version for 10m AM, an ultra-stable GPS locked frequency source to use on VLF and maybe microwaves later,  my permanent E-field probe and grabber for VLF/LF/MF,  an improved 136kHz stand-alone receiver, etc, etc. Hey ho!

More DX on 10m today

This must rank as one of the most fun CQWW DX contests I've taken part in. Plenty of DX could be worked with just 5W SSB from the FT817 and my small Homebase-10 halo today and yesterday. If anything conditions were better on 28MHz today than yesterday.

HK1NA (worked today) operating CQWW

 ...and in contrast G3XBM operating CQWW today!

Stations worked include LR3M, LP1H (Argentina), C5A (The Gambia), HK1NA (Colombia), CR2X, CR3A, CT3HF (Azores), CN3A (Morocco), ER3AU (Moldova), A65BB (UAE), 3V8BB (Tunisia), ZW5B, ZZ2T, PY1NX, PS2T (Brazil), EY8MM (Tajikistan) plus loads of US, Canadian and other stations. My ears are sore with SSB signals! I have now filled my third page of contacts in the logbook.

Some of the operating skills were amazing: PJ4X was working stations at a rate of one every 5 seconds. He spoke so crisply and quickly that by the time I'd called he'd already worked another station! 

First signals seen on JT9-2 mode

On 500kHz this morning PA0A and G3ZJO were testing with the new JT9-2 weak signal mode. Not yet copied Eddie, but PA0A was coming through well. This is a screenshot with his decoded signal overlaid.

500kHz first JT9-2 signal received

Choice DX on 10m SSB today

The CQWW DX Contest continues to brighten up things on 28MHz SSB, although the competition is fierce for some of the rarer stations.

XV1X QSL card

Some DX is surprisingly easy to work though, responding after just a couple of calls with QRP.  My 5W QRP SSB got through to EY8MM and A65BB but failed (so far) to work XV1X (Vietnam) or JT1BV (Mongolia).

JT9: a new digital mode for MF and LF

Hot news from Joe Taylor K1JT on the RSGB LF Yahoo group this evening about a new 9-FSK digital communications mode (for 2-way QSOs rather than beaconing) optimised for MF and LF bands. With winter approaching and better LF conditions, this is an exciting development.

The wide graph display for JT9

"I invite you to try a new digital mode called JT9, designed especially for making amateur QSOs at MF and LF. JT9 uses the structured messages introduced in 2003 for the JT65 mode, now widely used for EME and for QRP operations at HF. JT9 can operate at signal levels as low as -27 dB (in a 2500 Hz reference bandwidth), with one-minute timed transmissions. It also offers slower transmissions of 2, 5, 10 and 30 minutes duration, and the slowest mode can decode signals as weak as -40 dB. With one-minute transmissions, submode JT9-1 has a total bandwidth of just 15.6 Hz -- less than one-tenth the bandwidth of a JT65A signal. The other submodes are narrower still: a JT9-30 signal occupies about 0.4 Hz total bandwidth.

Note that these JT9 sensitivity levels are comparable to or better than those of WSPR, which uses simpler messages and is not intended for making 2-way QSOs.  JT9 has much higher throughput and reliability than QRSS CW, including DFCW modes.

JT9 is implemented in an experimental version of WSJT called WSJT-X. Some further details can be found at http://www.physics.princeton.edu/pulsar/K1JT/WSJT-X_Quick_Start_Guide.pdf , and an early version of WSJT-X can be downloaded from
http://physics.princeton.edu/pulsar/K1JT/WSJTX_01r2695.exe.

Please note: WSJT-X is in an early development stage. A number of improvements and enhancements are already in the works, and others will surely be added. 

Your feedback will be much appreciated!

-- 73, Joe, K1JT"

CQWW SSB DX contest 2012 (28MHz) - a recording

Well, Oct 27th 2012 and the CQWW DX contest is in full swing. 28MHz is filled with SSB stations all the way from about 28.25MHz right through to 29MHz, with even a few SSB stations on top of the AM users around 29.05MHz. Conditions appear to be excellent for the contest and they are likely to hold up for tomorrow too.  I was able to work 5 continents in 50 minutes this morning with 5W SSB and a halo.
 
In 5 years or so, this day will seem like a dream with 10m probably dead and devoid of activity. So, for posterity, I made a sound recording late this morning of the 10m band as I tuned across it and later this video at around 1630z.

Here is an earlier sound recording CQWW SSB DX contest 1125z October 27th 2012. Recorded near Cambridge, UK.  Feel free to share/use this recording and video. I only made them for posterity so I can remember, in years to come, what 10m was like at a sunspot peak.

Chromebooks?

This week saw the launch of Windows 8. Also, Google launched a new Chromebook 11.6 inch PC manufactured by Samsung which is getting rave reviews. Chromebooks use Google's Chrome OS which is very much linked to Cloud based operation.  The new series 3 Chromebook is only £229 from John Lewis complete with a 2 year warranty. In the USA it is available for $249. Now, when I looked I could not see any amateur radio apps for this OS. They will surely come though.
UK retailers include PC World, Amazon and John Lewis. They seem to be selling FAST.

Although I am not sure why, this PC really appeals to me: it is simple, small and effective. The local machine remains uncluttered and safe to use as most of the applications work remotely "in the cloud" although Gmail, Goodle Docs and lots of other apps will work without an internet connection too.

Has any reader used a Chromebook? What were your impressions?

VLF DX radiated test results

My days long, continuous carrier test with G3WCD (32km) and G3ZJO (around 50km) around 8.977188kHz ended yesterday. I was using my 20m spaced earth electrodes with 5W out of the PA. The test was to see if anything at all could be detected well beyond the 6km I can repeatably obtain with QRSS3 earth-mode (through the ground) communications.  Despite the hint of a signal a couple of times on the G3WCD 45uHz and 22uHz grabbers, these proved to be false signals and nothing was detected.

Using Spectrum Lab, locked to a VLF MSK signal I am able to measure my TX frequency with VERY great accuracy, in fact to an accuracy of less than 1mHz. What this showed up was that my crystal controlled TX drifted (very slightly by HF VFO standards) about 13mHz over the 4 days of the test. Starting frequency was around 8.977177kHz and the final frequency 8.977190kHz. With shack temperature variations it may have moved slightly higher or lower too.

When the RX stations are looking for a very very weak signal in a bandwidth of 22uHz this means the signal is only "within band" for the FFT software to analyse for a brief period before drifting out of the measuring "bucket".  To have ANY chance it will be essential for me to lock the TX frequency so that it stays within a few uHz over a period of days. This could be done using a GPS reference signal or using Spectrum Lab. It is the latter that I shall be trying - receiving a VLF MSK signal on one antenna as the reference, then using SL to synthesise the continous TX carrier which is transmitted on a second antenna.

In reality to get 32km on VLF with my set-up was always a "long shot", but all parties agreed it was worth trying and we have all learned a lot in the process. Experimentation is the name of the game and failure is as important as success.

It may be some time before I try the long range VLF tests again: I hope to have over 100W next time and a super-stable TX signal. Who knows, we might just succeed next time.

For information on these software packages (all free) that I use at VLF see https://sites.google.com/site/sub9khz/software .

My 10m halo - soon time for an overhaul

After the CQWW DX contest this weekend I plan to take down my Homebase-10 halo and rebuild it. The birds have managed to tear away at  the nylon rope supporting the nested 6m halo and the wooden supports now look a bit weather beaten.

So, I plan to replace the wooden cross frame supports with PVC pipe or fibre glass rods and re-do the wire elements. These have been up in all weathers for around 4 years now, so a few pounds on a remake is justified. The antenna works so well and is so small that I cannot think of a better antenna for the 10m band short of going to a beam which would be huge by comparison and need a rotator. The neighbours are quite used to it too, which is good.

Ten-Tec Argonaut VI latest

Ten-Tec is working on a new Argonaut transceiver called the Argonaut VI.  Details remain sketchy but at K4SWL's website http://qrper.com/tag/model-539/ there is some news that 25 units are going through a pilot run currently with production likely towards the end of the year.

A photo of the Argonaut VI on the K4SWL website (linked)

There are not enough details available to make any judgement on this new QRP transceiver. As far as I can find there is nothing at all about it on the Ten-Tec website. Some rumours are that it will NOT cover 12m and 6m and neither will it support 10m FM. Who would produce a brand new HF radio without at least all 80-10m inclusive bands and modes?

Unless the price is very attractive and the unique features substantial, then I just cannot see it competing well against the 11 year old FT817 and the new Elecraft KX3. The pictures seen so far show a simple looking radio, some would say plain, but with what is supposed to be a very decent receiver along the lines of the Ten-Tec Eagle.

What's cooking Ten-Tec? Are you still going ahead with this transceiver? If so, please can we have some firmed-up specs and prices?

CQWW DX SSB contest this weekend

Although not a serious HF contester - I have never submitted a log -  I do enjoy a fling in the CQWW DX SSB contest at the end of October each year, usually on 28MHz.

The most I can run is 5W pep but, if conditions hold up, there should be little problem in working stacks of US and Canadian stations as well as loads of others worldwide.  This year I have a speech processor which appears to make a good 1-2 S-points difference and makes working DX much easier.

Especially towards the end of the contest there are plenty of big contest stations looking for new contacts. If you want to work some good DX plus new US states and Canadian provinces, then this coming weekend will be your best chance.  In my experience running QRP SSB is no barrier at all to working LOTS of DX in this contest.

Some people love contests on HF and VHF and others hate them. Personally, I am happy to enjoy the DX opportunities they provide and tolerate the heavy band usage they bring, albeit for 48 hours in the case of the CQWW.

CQ zones map

Exchange is report and CQ zone. In the UK we are zone 14, so a typical report would be "5914"

Low cost weak signal work from VLF to light

Well, I do get about a bit - in the spectrum that is!

1. At the moment I am running a test transmission on 8.977188kHz (precisely) to G3WCD who is trying to detect my VLF beacon in a 22uHz (yes micro-Hertz) bandwidth over several days. Chris is 32km away.
2. I am running WSPR on 28MHz with 200mW and, for the second day running, my QRP signals have reached Australia.
3. In 2 weeks time (when the grandchildren have gone home) I will be resuming my over-the-horizon QRSS tests on 481THz (red light) using my high power beacon and more sensitive detector. The signal is too weak to see by eye, yet the sensitive kit can detect it.

All three of these have one thing in common: the circuitry to do them all is very very simple and the kit cost just a few pounds to build.

Over-the-horizon 481THz optical signal from G4HJW last winter

In each case though the processing power of a PC is used to help extract weak signals from deep in the noise. Luckily the software in each case is absolutely free: Spectran and Spectrum Lab for VLF and optical frequency detection and WSPR software for the WSPR tests.

Homebase-10 28MHz wire halo antenna

Homebase-10 antenna on the back of my house.

28MHz (10m) is excellent at the moment. If you are looking for a small, simple, horizontally polarised, omni-directional antenna for 28MHz, you may want to build a copy of my Homebase-10 halo which was published in Practical Wireless a few years ago. This antenna takes hardly any space, is simple and inexpensive to make and works extremely well. All the parts apart from the wire can be obtained from your local hardware store (wood, brackets, screws etc). You should easily have change from a £10 note.

The results on WSPR today (see previous post) give some indication of how well it performs. Mine currently has a second halo nested inside the first giving me coverage on 50MHz too.

WISPY spans the globe

Today WISPY, my little 10m 200mW WSPR beacon, excelled itself getting spots from 5 continents with the best being a spot from Australia late this morning. 

Conditions in the last few days have been excellent. I keep reminding myself that if, as some are now saying, cycle 24 has already peaked and we are on the way down, conditions in my lifetime (and probably most of those reading this) are unlikely EVER to be as good again.  It is just possible there may be a second peak next year which is stronger, but I somehow doubt this now.

Unique 10m WSPR reports with 200mW and a halo today

10m QRP (2W) AM DX QSO

The excellent conditions on HF today

Just worked K1IED in Connecticut when using 2W AM to my halo antenna. The 10m AM segment is busy with some good signals from the US and Canada. When 10m AM is like this you just know 10m is wide open.

Although K1KW was an excellent AM signal I was unable to get through the pileup on AM to work him.

The very poor quality video below shows K1IED's 10m AM signal a few minutes after I worked him.

Simple 10m AM transceiver?

Yesterday, someone suggested that I build a simple 10m AM rig. Now clearly the best option would be a DSB transceiver for which I have many of the ideas clear in my head and implemented in my WISPY transceiver for WSPR.

However, I think it would be fun to make a 10m version of my Fredbox and Sixbox QRP AM transceivers. These are to be described in an article in Practical Wireless. For local nattering I think more output is needed on 10m, probably 1-2W AM. A low level series modulator followed by a single stage linear amplifier is a simple way to go on TX. For receive, a super-regen receiver would be fine for local use when the band is not busy. This is 75% of the time at least and almost 100% of the time in the evenings, most times of the year. It would be unsuitable when the band is very active, as currently during the day. A better AM receiver could be built, but nothing beats a super-regen for elegant simplicity, as long as it has an RF amp to isolate it from the antenna.

Maybe this is a quick project for a few autumn afternoons. A few watts of AM on 10m should span several miles locally with a vertical or a dipole.

472kHz Transverter Updated

A few people have now successfully copied the transverter design. I have just updated the webpage describing it and corrected a few errors on the schematic. Also, I have shown an additional low pass filter on the output which is prudent. It should not be necessary with a sharply tuned short Marconi or loop antenna.

See https://sites.google.com/site/g3xbmqrp/Home/472khz-transverter for the updates.

Rev H 472/500kHz Transverter Schematic (click to enlarge)

Petrol from air and water???

The BBC Business page carried a story this week about a company in NE England that is developing a technique to produce petrol from air and water. This sounds like something too good to be true, but if scaled up to production levels could be something remarkable.

"A British firm based on Teesside says it's designed revolutionary new technology that can produce petrol using air and water. Air Fuel Synthesis in Stockton-on-Tees has produced five litres of petrol since August, but hopes to be in production by 2015 making synthetic fuel targeted at the motor sports sector. The company believes the technique could help solve energy supply problems and curb global warming."

See http://www.bbc.co.uk/news/business-20003704 .

Another 472kHz transverter copy

LA5VNA's version of the G3XBM 472/500kHz transverter

Steinar LA5VNA has built a copy of my 472/500kHz 10W transverter and showed a copy of the design on the RSGB LF reflector today. Like G3ZJO, Steinar's is giving over 10W (more like 15W) output. To my knowledge there are now 3 copies of this design built and working. I recommend the addition of a second low pass filter to improve the harmonic content. The one from GW3UEP's QTX transmitter would be ideal (2 x 6n8 caps and a 15uH inductor).

IC7100

As yet, I have not heard any more firm news on price and availability of the IC7100.  There was a rumour that the US price was going to be around $1875, but I have no idea where this figure came from. If correct, it sounds far far too much.

Although I am a QRP person, this rig does appeal to me: the very comprehensive band coverage (including 4m) would make it a good main station radio. With the IC7000 being just over £1100 I would expect the IC7100 to be somewhat more than this, at least at first, but not as high as the figure above which would translate to around £1875 with import duties, VAT and dealer mark-ups.

IC7100 - will there be a QRP version available in the USA and Europe?

What would be really nice would be an "IC703 version" of the IC7100 i.e. a 10W pep version. Now if Icom  produced one of these a lot of QRP enthusiasts would sit up.

10m comes to life big time

This afternoon I took a look on 28/29MHz and the band was WIDE open. We are close to the sunspot peak - some would argue just past it - and at this time of the year conditions on the higher HF bands are at their very best. If you have never worked on 10m get on now (especially for the CQWW DX SSB contest next weekend!) and enjoy it whilst it is so very good. In 5 years from now the band will be very very different with just the occasional African and South American openings and Es propagation.

K1IED who worked many QRP AM stations on 10m today

When conditions really are this good, I recommend listening 29.0-29.1MHz for DX AM stations. Today there were some excellent AM amateur signals to be heard from the USA and Russia. K1IED was S9+ with his 250W to a big beam and he managed to work several QRP stations from Europe. In the past I have worked the USA with a few watts of AM but time prevented me having a decent try today. Andy G0FTD managed to work him with just 1W. You can see his video here.

Listening to 29.0-29.1MHz AM when the band is in good shape is like entering a time warp taking you back to how amateur radio sounded in the 1950s and early 60s. Wonderful.

Just maybe DX on 8.9755kHz?

Last week G3WCD, who is 32km from me, monitored my very long carrier VLF transmission to see if he could detect anything. I transmitted a continuous carrier for a day with a 1 hour break during the period. On his 45uHz bandwidth VLF grabber he noticed a signal (me?) very close to my stated frequency that disappeared the day after, when I was not transmitting. So, starting late tonight, I am repeating the test with an even longer continuous transmission (days if need be) to see if the carrier re-appears on his screen. Should the signal appear, I will drop carrier for a day or so and then re-key the TX to see if the signal re-appears.  At this distance I would be very surprised if anything would be detectable, but this is certainly worth this second, longer, try. Chris G3WCD has a VLF grabber at http://g3wcd.bplaced.net/.