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/

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

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?

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

Early morning (Jan 22) saw BCB conditions vastly improved over what they have been for most of the season. Because I am on the wrong (none-Pacific) side of Vancouver Island, as well as on the eastern shores of Mayne Island, I usually don't listen for Asian signals on my Perseus recordings but a quick check of Thursday's recordings revealed some very solid signals from many Japanese stations, as well as Korea. Most signals were strongest at around 1500Z (7 a.m. local) but were first audible from about 1200Z.

Three of the good performers are shown in the video below:

• JOBB  828KHz NHK2 Osaka
• JOAK  594KHz NHK1 Tokyo
• HLAZ 1566KHz Jeju, South Korea / Far Eastern Broadcasting Company

Numerous other signals, reaching similar strengths were audible throughout the broadcast band on their 9KHz-spaced channels. Interestingly, I had configured my LF inverted-L into a temporary version of a low noise vertical (LNV) by removing all of the loading coil and feeding with an isolating impedance matching transformer. I rather suspect that in this mode it is acting as a normal quarter-wave inverted-L however as its self-resonant frequency, without any loading, is around 1200KHz. Today's conditions were much poorer but several Asian signals were heard once again.

Should conditions improve, the next time I will use my large loop oriented to favor Japan and also take advantage of its ability to null many of the local blowtorch signals from Vancouver, off to the side.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

QRP is fun.  That's why I do it. But one of the side benefits of QRP (and there are MANY), is the people, the QRP community. Since becoming a dedicated QRPer, I have made friends with so many really fine people. I can't begin to tell you of how many friends I have that I have never met face to face. And I maintain closer friendships with some of these people than with other folks I actually "see" on a regular basis.

To emphasize this point, here's a story that one of those friends, Jim W1PID, posted on QRP-L today:

An hour ago I got a call on my cell phone. The caller ID said New Jersey. Must be a telemarketer I think, so I don't answer. A few minutes ago another ring from the same number. It's Guy N7UN. 

"HI Jim... this is Guy N7UN... did you call me?" 

I explain that I got a call from him that I didn't answer. Well... turns out he's doing a SOTA activation on the highest mountain in Maui! 

"You gotta rig?" I ask. 

"Ya", he says." I'm on 14.062."

"OK, I'm going to the shack." 

So I just had a QSO with Guy in Maui.  Wow and Mahalo!

Larry Makoski, W2LJ, is a regular contributor to AmateurRadio.com and writes from New Jersey, USA. Contact him at [email protected].

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.

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

This is the 139th installment of Linux in the Ham Shack. In this episode, your co-hosts have a rollicking good time while managing to discuss some important topics. Those topics include: using breathing as Morse Code, satellite communications with a handheld radio, Linux Mint, computer security, electric cars and much more. Thanks for listening, and please donate to our Hamvention Indiegogo campaign if you can.

Russ Woodman, K5TUX, co-hosts the Linux in the Ham Shack podcast which is available for download in both MP3 and OGG audio format. Contact him at [email protected].

 

• WE'RE BACK!
• Michigan gets its own PRB One antenna law
• A launch date for the Fox 1 hamsat is announced
• ARES called out in Ohio to assist after phone outage
• The flight of the V-K around-the-world floater balloon falls short of its round-the-world trip
• The K-one-N Nevassa Island DXpedition will be on the S-Oh 50 ham radio satellite
• And old Sol is at it again!

 

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