SHAMateur radio

Today the December 2012 RadCom dropped on my doormat.  P16-17 contains a review of the Acom 1500 1500W linear amplifier for HF and 6m. Now, I am sure this is a very well engineered piece of kit, but at £2750 including VAT surely this is not for real amateur radio?

Anyone buying this has probably spent a few thousand on a big Yaecom black box multi-mode HF rig, another £400-500 on a beefy rotator, another few hundred on a mast and another few hundred on an HF beam to put on the top. Total bill for all this approaching £5000 if not more! They may be able to work some DX slightly more easily than me with a 5W or less radio and a small wire antenna strung up in the tree, but I bet they have less fun.

I have no objection per se to people spending the money they earn as they choose, but what I object to is this sort of expensive kit being projected as a necessity to enjoy our hobby.

To my mind this is SHAMateur radio, not amateur radio. It is a cheque book hobby far far removed from the hobby I wish to be associated with.

I wish our national magazine would publish more articles about REAL amateur radio, the sort that young kids and people on tight budgets can afford and enjoy. If the RSGB is short of material then it should ask the GQRP club for some ideas and circuits! Amateur radio is a very varied hobby and I do not want to be a killjoy, but anyone picking up RadCom would believe you need a very deep wallet to be able to enter the hobby. This simply is NOT the case. OK there is some good beginners content (for example the excellent series by Eamon Skilton) but not nearly enough.

One thing that IS good in this month's RadCom is the review of QRP Basics by G3RJV on p39. The first edition of this was a very good book that showed what amateur radio is really all about. I expect the new second edition will be even better. I commend it to you!

Are you a radio amateur or a radio shamateur?

Dell Inspiron 1545 power socket repair

My wife's laptop is a 3 year old Dell Inspiron 1545. Although otherwise a nice PC, this has a stupid design weakness: the power connector socket. This is on the side of the PC (back left) and it is almost impossible to use the machine and not snag the cord and socket regularly.

Consequently, over time, the SMA connector inside the PC has gone intermittent. The PC is covered by a 4 year hardware warranty and I hope that Dell will just fix this and not argue "wear and tear". I have had other PCs where the power socket is strain relieved within the housing and not had a problem.

One has just to look at the number of videos telling you how to fix this very issue to see it is a very common one. I like this video showing the repair in 3 minutes, although in reality it would take about 1 hour. In the limit I could do it myself, but let's see if Dell are in a good mood and are helpful first!

I do get really annoyed when a consumer product goes to market with such an elementary design weakness: this is the sort of rubbish that should have been spotted early in the design phase by design reviews looking for possible failure mechanisms. Dell should know better.

Tenbox progress (10m QRP AM transceiver)

Tenbox breadboard RX -115dBm MDS

Today I breadboarded a simple, but sensitive receiver for 10m AM in the Fredbox tradition. The standard Fredbox and Sixbox circuit was simply scaled down to 29MHz with great results using the breadboard with the Marconi 2022 generator. MDS for a well modulated AM signal is better than -115dBm (around about 0.5uV) which is actually better than I was achieving on 6m and 2m. Not bad for just 2 MPF102 FETs and 1 2N3904. For the tuned circuits (RF amp output and detector) I used a couple of T37-6 (yellow) toroids tuned with 15pF trimmers. There is a 10pF coupling capactor between them.  Of course this is a super-regen with a grounded gate RF amp to isolate the detector from the antenna.

The intended use of the Tenbox is local "across town" nattering when the band is quiet. The selectivity would NOT be suitable for DX use, although I'm sure it would pick up stateside 10m AM stations OK.  I am always amazed by how well a simple super-regen RX works: they just fly for me and are always incredibly sensitive and non-critical. People who have not played with these do not know what they are missing. I highly recommend the RX in the Fredbox

Next stage is to breadboard up a simple AM modulator and TX strip. Again, I shall copy the basic Sixbox design but this time add a linear amp (a few 2N3904s in parallel as in the WISPY beacon) to get the carrier power to a useful level.

In summary, an interesting and productive hour or so after tea.

Weak signalling comparisons

Over the last few days I've been trying out my Lesser Chirpy 10m 80mW CW rig putting out CQ calls on 28.060 periodically and listening for replies and RBN reports. In three days I've only managed 2 RBN reports at around 3000km with it. So, this morning I fired up the hombrew WISPY WSPR beacon on 10m to see what happened. This runs about 6dB more power at around 200-250mW pep effective on the WSPR band. On the first transmission I got 3 reports immediately at 2200-3500km. With WSPR it is SO much easier.

Conclusions? Well if you just want to know what propagation is like then a small homebrew WSPR beacon is all you need. If you want the fun of the chase and the chance of a few QRP CW contacts with a human then the Lesser Chirpy rig is up for the challenge.

Life is too short to sit there endlessly calling CQ with the key though. So, I think Lesser Chirpy will be brought out when  conditions and activity are good. Otherwise WISPY will whisper away quietly in the shack whilst I get on with designing interesting new little projects, HI.

UPDATE: After a few hours of 10m WSPR at 200mW I had a page of reports out to around 6500km. Back on 10m CW I tried a brief call with the FT817 at 5W and got a couple of USA spots on the RBN. A further 30 minutes of calling CQ with the 80mW transceiver and no reports or QSOs. Think I'll have to come back to 10m QRPp another day!

AM broadcasts on Medium Wave

The BBC recently switched off some of its MW local radio AM outlets for some weeks to see if anyone was listening. Results suggest few people listen to their radios in the UK on Medium Wave any more. I know I am one of them, preferring to use Band 2 FM. We also have a DAB radio but it is pretty useless in the kitchen where FM is perfect. I think it is a signal strength issue.

So, will the BBC switch off all its MW output? Will anyone care? It may soon be that AM will be a dying mode unless we radio amateurs use it and show its strengths.

See www.theregister.co.uk/2012/11/08/dab_am_bbc/.

Microsoft Essentials virus protection

On our regular local Monday night 2m net on 144.575MHz (in the all mode section) - anyone is welcome to join us in the East Cambridgeshire area - the subject of PC virus protection came up tonight. Some months back someone told me about Microsoft Essentials which is a free virus protection package. I still use McAfee here and have another year to run on it, but wonder what people think about the free Microsoft package? Does it work well?

More DX on Lesser Chirpy

Another report via the Reverse Beacon Network from 5B4AGN in Cyprus this morning, but no QSOs and no further RBN spots. A brief outing this afternoon in which I'd hoped to get across the Atlantic proved to be a disappointment. There is always tomorrow....

The Argonaut VI is coming soon....

Just received this reply from Stan WD0BGS at Ten-Tec regarding the progress with the Argonaut VI. It sounds like they are now very close to releasing it.

"Hi Roger,

The Argonaut VI model 539 is in beta testing as we speak.  Our first production has gone into the hands of many users to determine any slight improvements before the second production run begins next month.  Our web site will be turned on and ready to place orders when all final numbers have been established and any firmware changes have finalized.

The price of the Argo VI will be $995 and available around December/January time frame +/-  The Argo VI will not be a kit and it will be a small 1-10 watt output multi-mode QRP transceiver.  It will not contain 60 meters or 12 meters due to the design and size restrictions.  Watch our web pages in December for release notes and a page about the Argonaut VI.

Sincerely,

Stan Brock, WD0BGS"

Now, I have not done the sums yet, but $995 does not sound like a very competitive price for a radio that misses 2 HF bands out. The Argonaut has to be a seriously good radio when put next to the Elecraft KX3, but then Ten-Tec know this only too well. They must have decided this price is right and it will sell.

The UK price tends to be close to the US price but in pounds. If importing from the USA directly we have to add Royal Mail handling charges (£8) and VAT at 20%. I gather import duty is not payable though. Against a 10 year old FT817 this looks like a lot of money.

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.