AmateurRadio.com

Well designed DSB transceivers are much simpler than SSB rigs as no SSB filters and mixing to final frequency is needed. They must not be over-driven to avoid a spreading signal. The PA needs to be linear too. These issues being carefully considered, you end up with a rig that has the same bandwidth as an AM rig but with a suppressed carrier. DSB transmitters are usually received as an SSB signal. The downside is that if a simple direct-conversion receiver is used then there is no rejection of stations sitting on the other sideband. So, they are best on quieter bands, rather than busy HF bands. Bands like 10m, 6m and 4m are probably good candidates.

Although not impossible, it is quite difficult to demodulate a DSB signal on a simple direct-conversion receiver. DSB rigs are ideal as simple transceivers to communicate with SSB rigs.

See http://home.alphalink.com.au/~parkerp/projects/projmicro40.htm

Also: https://aa7ee.wordpress.com/2013/10/19/the-vk3ye-micro-40-dsb-transceiver/

As you may recall, I am quite a fan of super-regen receivers. Nothing as simple is able to match their AM sensitivity, but they tend to have poor selectivity.

With the availability of very low cost 433MHz modules (TX and super-regen RX) designed for AM data, these modules could be ripe for conversion to ultra-simple 70cm AM voice transceivers. One local friend, Andrew G6ALB, is currently carrying out experiments to see if this is feasible. I hope to work him on 70cm AM using such a rig in the months ahead. Sadly, I am still too clumsy to do any building work – very frustrating.

I am wondering if anyone else has tried these modules in such a circuit? With a simple MMIC PA (50 ohms in and out) the power output could be lifted to around 25mW carrier or more. With V2000 verticals this should be good for local ranges. Even at the low milliwatt level from these QRPp modules several km range should be possible with co-linear antennas.

UPDATE 2310z:   I wonder what sort of power the TX modules typically produce with linear (speech) modulation rather than 5V square wave data modulation? Presumably much less than their rated power, so an add-on PA may be essential?

Around the world, several administrations allow some access to 5MHz for amateurs.  Mostly, these are channelised allocations, which are far from ideal. What is needed is a continuous 60m band, say 200kHz wide. There was/is some hope of this being allocated to the amateur service at WRC2015 which is due to take place late this year.

I wonder what the chances of radio amateurs getting this band are? I have rather lost touch with the news on this. Certainly it was to be an agenda item. With decreasing solar activity, this would be ideal for the amateur community. I do hope it happens. Even if allocated at WRC2015, it could be a few years before administrations can make the necessary changes. If anyone has any further news I’d appreciate being updated.

Hobby to get exposure to publication’s 2.3 million readers

The March 2015 edition of American Legion Magazine will include a feature article about the hobby of amateur radio. Written by best-selling author Don Keith N4KC, the article will tell readers of the publication how ham radio remains exciting, important, and relevant, even after one-hundred years of existence and so much technological change. It will also remind American Legion members about their organization’s own club—The American Legion Amateur Radio Club or TALARC—as well as how its members can get their licenses, establish club stations at more of the 14,000 posts around the country, and more. The Legion has an agreement with the Department of Homeland Security for assistance during emergencies and the article talks about how amateur radio meshes well with that effort.

American Legion Magazine is distributed to the veterans’ organization’s 2.3 million members as well as through other outlets. TALARC now has more than 2,000 members. Regular on-air nets are held for Legion members who are also hams. The club station, K9TAL at American Legion Headquarters in Indianapolis, Indiana, also hosts regular operating events.

To learn more about how the American Legion is integrating amateur radio into its organization and for its members, visit www.legion.org/hamradio.

The author of the article, Don Keith N4KC, is a best-selling writer with more than two dozen books published. His submarine thriller, FIRING POINT, co-written with former submarine captain George Wallace, is now in production as a major motion picture under the title HUNTER KILLER. He has written extensively about World War II history, submarines, college athletics, NASCAR racing, and broadcasting, including WIZARD OF THE WIND, a novel with a key character who is a ham. His next book, THE SHIP THAT WOULDN’T DIE, will be published by Penguin/NAL in April 2015. It tells the true story of a remarkable event during the Battle of the Coral Sea in 1942. Don has also published a book on his favorite hobby. RIDING THE SHORTWAVES: EXPLORING THE MAGIC OF AMATEUR RADIO explains to newcomers and old-timers alike how the hobby is even more dynamic today than when it was first introduced a century ago. All Don’s books are available wherever books are sold.

Don is an ARRL member, an Extra-class licensee, and has been a ham since 1961. He is very active on the air and operates most modes and bands. For more info on Don Keith N4KC visit www.donkeith.com or www.n4kc.com.

Because of my poor voice (as a result of my cerebellum brain bleed) I tend to use digital techniques, like WSPR and JT65, but I still enjoy AM.  Like many, I’ve worked transatlantic AMers on 29-29.1MHz with real QRP and simple antennas using AM. It makes a great change from SSB.

One could be forgiven for thinking AM is a dirty word at the RSGB.  In UK Band Plans published in the February 2015 edition of RadCom, AM gets no mention on 28MHz and 50MHz and gets a (begrudging) comment as a footnote only in the 144MHz Band Plan when other modes get “centres of activity” mentions. AM is alive and well in the 29-29.1MHz sub-band. AM on the 144MHz (2m) band here in the UK can be found on and around 144.550MHz. There has been AM on 29-29.1MHz for years and years and years – in fact almost as long as I’ve been active on the air. Yes, this is in the all-mode section, but why not say this is the 28MHz (10m) AM sub-band? Also, why are 144MHz AM users asked to “consider adjacent channel activity”? AM should easily fit in 6kHz!!

Yet again, AM is being treated as a dirty and outdated mode. Here in the UK, ex-PMR AM rigs ripe for use on VHF can be picked up for virtually nothing and there is certainly room for AM on all bands from 28MHz upwards. AM has its enthusiasts on other bands too, but yet again the RSGB seems keen to kill off this mode. Why I wonder?

Allegedly, a RadCom article on digital TV in the 146-147MHz band was pulled last month at the last minute because “someone at the RSGB” thought it would not fit in the new band! Sometimes one wonders. Maybe the day when I only get SPRAT is closer than I thought? Thankfully, there are many good articles in RadCom.

Some nights 40 meters have been very good recently, with north American and European stations coming in. Other nights you might encounter a lot of this….

It’s annoying, but at least you know propagation favours southeast Asia. To get some perspective on these “pirates” I googled a bit and found a post from 2003 on eHam.net with some insight from John Davies, 9V1VV, whom I worked recently. Let me quote him….

We in Singapore face daily obstacles getting through SSB pirates on all HF bands. They operate up to 5KW in all sections of the bands including the designated CW portions. On the lower bands, the only way to hope to work DX from here through the QRM is in the middle of the night when the Indonesians are sleeping.

Not only the Amateur bands, but ALL frequencies from 1.6 to 30 MHz, are affected.

The reasons are complex, and no efforts by radio amateurs will change matters.

I was involved in a large Indonesian Government project in 1996 as installation and commissioning engineer for 15 Marine Coast Stations, in locations across the length and breadth of Indonesia from Sumatra to Irian Jaya and north to the Philippine border. It was a great adventure for me, and I have many tales to tell.

What is of interest here is that the radio operators in these remote islands would hold evening nets on SSB for the mothers and fathers, uncles and cousins, of young men working in other regions, usually in the cities where they had gone for work. Operators in the big cities such as Jakarta or Surabaya would arrange with these young men skeds for many islands all over the vast country, for a small fee of course. These larger city Marine Coast Stations often use up to 5KW PEP, free-running transmitters. The stations I was commissioning were only 600 watt, but they were also free-running 1.6-30MHz.

It is not only the marine radio operators that cause problems. The police, army and airforce bases work on the same lines. There are thousands of Japanese rigs out there free-running in the hands of as many operators all over the archipelgo, all using radio as a kind of community service, in a country where landlines and cellphones cost money and are far from reliable.

The operators are poorly trained or dismissive of the niceties of international regulations and procedures. For example, a common calling frequency is 10.000 MHz !! It’s an easy figure to remember. The low portions of the amateur bands are fair game. The operators often remark on the “birds” tweeting (CW ham operators) but ignore them or force them off the air. I have heard a QSO between villagers in the coastal town of Panjang in southern Sumatra talking with their relatives in Yogyakarta on 9.750 MHz, right in the middle of a commercial band!

I do not see the situation changing in the near future. The pirate Indonesians will continue undiminished in number. There is no local authority in existance to challenge them. And the Indonesians are a gregarious people and thrive on chat and scandal. Radio is the medium for this.

It makes working the ham bands in southeast asia a real adventure at times.

I have successfully chased away some rogue operators from the 20 meter CW section who interfered with me, so it can be done. But since 2003 little has changed and working the ham bands in Asia is still a real adventure at times.

These are bands I rarely use, but some readers may be interested in the Hendricks Kits dual band transceiver. 5.5W sounds enough to work plenty.

These days, the main issue on these bands can be man-made noise from TVs, SMPUs and similar. At my old QTH I had an S7-8 noise floor on 160m and 80m. At the new QTH the noise floor on these bands is low currently, but this could change overnight. Some people use loops and nullers on RX to minimise problems. If you have a quiet noise environment then this transceiver may fit your needs. Don’t forget you will need a reasonably big antenna to get decent results. A half wave 160m dipole antenna is around 240 feet long.

In my youth we had rigs like the Codar AT5 12W AM/CW 160m/80m transmitter and companion T28 RX. I had the RX but not the TX although I did use an AT5 from the QTH of the late G4PJ. The T28 was mainly used as a tunable IF for my 2m converter. I heard my first 2m satellite signals via Oscar 6 and 7 using the T28 as a tunable IF. I remember being very thrilled hearing my first transatlantic stations on the top end of 2m.

See http://www.qrpkits.com/mbdc.html .