30 Mar 2013

Low cost signal generators for QRP

Elecraft's XG3 signal generator
Although I have a couple of (loaned from friends) signal generators, these are rather large in a small shack. There are times when something small but calibrated is useful. Elecraft sell the XG3 signal generator which can be PC programmed to give a number of fixed output levels on a wide range of HF, VHF and UHF frequencies. It is the same (small) size as the T1 auto ATU i.e. about the same size as a packet of cards.

The Norcal S9 signal generator
Norcal also sell a kit for a small fixed frequency signal generator called the S9 Signal generator that can provide a fairly well controlled range of output levels. Currently it is out of stock, but the circuit is simple and could easily be built from scratch "dead bug" style.


Writing for radio magazines

In recent years I've written articles on a wide range of subjects, from VLF to optical, for several different radio magazines around the world. Now I don't do it for the money as I have a pension that covers my needs adequately, but I am surprised how poorly radio magazines do pay authors. This may be one reason why they find it hard to find new authors.  I won't quote figures here as I don't want to embarrass anyone, but you have to write articles for the pleasure of doing so and not for the financial rewards, especially when tax is deducted.

One of the lowest payers appears to be the ARRL, which I find particularly surprising considering that QST must have one of the largest circulations in the world. Considering how long it takes to put a decent article together  with illustrations and schematics (very many hours), the rewards are probably better if one stacked shelves at a local supermarket or worked on the local dustcart.  It doesn't exactly encourage budding authors.

Times are hard and revenues in amateur radio magazines from adverts is probably falling, but reading QST, Practical Wireless and RadCom I see pages and pages of adverts that must bring in a decent amount. Maybe they'd get, and keep, more readers if they encouraged people to write interesting articles by paying a little more?

Royal Mail - postal/packet costs

I'm frustrated and actually quite annoyed with Royal Mail.  Have you visited the barely understandable Royal Mail website recently?  All I wanted was to find out how much a small parcel (a book - the Scatterpoint compendium sold on eBay) would cost to send to Germany on Tuesday. It appears you now need a PhD to navigate the darn website and understand all the options. It is nearly as hard as trying to find a utilities tariff.

Having done a bit of eBay trading this last few weeks, I'm surprised how expensive it now is to send a small packet by post using Royal Mail or Parcel Force, even more so if sending it abroad. Unless I have misunderstood the incredibly confusing information on how to send a small packet to Germany, one weighing 760g costs an astounding £6.62. Go above 1kg and the rates are extortionate.

Thankfully we still have a helpful local post office staffed with people who try to sort this out for you. Not having receiving my doctorate yet, so unable to navigate the Royal Mail website, I'll have to ask the nice lady at the local PO for the price and a stamp.

Why can't we have a SIMPLE postage tariff based on weight and whether it has to go surface or by air? OK, add a few options if you want a guaranteed delivery.

28 Mar 2013

More Chinese QRP radios/kits

Chinese QRP kits and ready built radios seem to be everywhere. For example, see the KN-Q7A kit from http://www.crkits.com/ . This little 40m 10W or 20m 5W QRP SSB transceiver was designed by BA6BF.   Reviews on eHam.net are good (4.9/5 with 8 reports) so this is no toy radio.

http://www.crkits.com
I have the feeling this is an enterprising Chinese amateur making a bit of money selling a few kits rather than a major Chinese manufacturer, gearing up for the big time. However, this IS coming. Unless the big boys like Yaesu and Icom move to low cost manufacturing locations like China for the bulk of their products then their days are numbered. Honestly. 

Amateur DX Europe to Alaska on VLF?

There has been some excitement over the last few days as Lawrence KL1X has seen a signal on 8.9700kHz when the noise was low that just could be coming from Uwe DJ8WX near Hamburg. He has tried to find out if this is a locally generated artifact, but it seems not.
KL1X grabber monitoring 8.270kHz for intercontinental amateur DX
In the coming weeks DJ8WX is moving his continuous carrier VLF transmitter (a long carrier is needed to be visible in the incredibly narrow bandwidths needed to see anything at all) down to 8.270kHz which is a clear frequency in Alaska. The Alaska VLF grabber is already active and, as soon as Uwe starts up, we hope to see a weak signal appear. If this happens this will be the very first confirmed reception of an amateur VLF signal from Europe in North America. The VLF receiver Lawrence uses is a small E-field probe antenna high up in a tree in a birch forest.

DJ8WX has been a very good signal on VLF here in the UK on my own receiving system (an 80m sq vertical loop feeding a preamp feeding a PC running Spectrum Lab with a special 424uHz bandwidth .usr file). I have not listened for Uwe recently as my loop is down but G3ZJO has copied him well in the last few weeks on his grabber.
DJ8WX's signal as seen on the G3ZJO VLF grabber
If you are interested in amateur VLF then visit https://sites.google.com/site/sub9khz/ and check out the various preamps, grabbers and DX reports. It is possible to check out activity by looking at the various grabbers (VLF receivers linked to the internet) around the world.

I've left the Yahoo KX3 group

Since its early days, I've been receiving posts from the Yahoo KX3 Group, which is a group for people interested in this Elecraft radio. It was generating a huge number of daily posts: this month people have posted 1590 messages already! As it is now rather unlikely that I will purchase a KX3 - I simply cannot justify £1200+ for a fully loaded, if excellent, QRP transceiver - I decided today to leave this group.  That still leaves plenty of other Yahoo group messages to read.

I'm not sure how others read Yahoo Group messages, but I always choose

" - Don't get notified of the latest happenings. Read messages only on the web."

I'd be unable to cope with several hundred, possibly thousands, of additional emails from groups each week. This option is always available when you join a Yahoo group, or you can do it later by editing your group settings.

Voice of America cutbacks

In my early days as a shortwave listener, the various VOA transmitters around the world were popular station targets for reports. I even copied "this is the Voice of America, Monrovia" (West Africa) on my little 4 component SW crystal set.  Now I see that the VOA is having to cut back transmissions because of the USA's budget issues. Like many shortwave broadcasters, VOA is feeling the pinch in hard times. The shortwave broadcast bands are no longer the same as they were back in the 1950s and 1960s: there are fewer and fewer English language transmissions to be heard nowadays.

As an aside, and I try to avoid political comments in this blog but feel compelled to share this, I read today that the audited costs of the Iraq war for the USA are an estimated $767bn. With ongoing healthcare and support costs the final figure will be well over $1trillion. All nations make mistakes and enter wars they later deeply regret, including the UK. What saddens me is the total WASTE this represents: Saddam was no saint, neither are the Talibhan in Afghanistan, but there has to be a better way to change nations. The phrase "swords into ploughshares" comes to mind. Jaw jaw is better than war, war. Just think how $1 trillion could have been better used.

Rectennas and solar energy

Recently I read about some interesting work on Rectennas, which are combined antennas and rectifiers used to detect microwaves and optical frequencies. The work suggested that very high efficiencies may be possible at optical frequencies (around 70%, possibly more) using nanotechnology leading to much more efficient power conversion of solar energy. The correct term for these would be Nantennas. At my new house (move coming up in a few months) I will be considering the installation of solar photo-voltaic panels, but wonder if I should wait a few years in case technical breakthroughs with Nantennas could revolutionise these?

Back from Lincoln

For the last few days we have been on holiday in Lincoln, staying at the Old Palace Hotel (I an highly recommend this) just below the marvelous cathedral. Our room was high up and looked due south and had an excellent take-off.  Sadly I brought no radio gear with me though, so was unable to take advantage of the site.

24 Mar 2013

Clear air forward scatter optical kit

The schematics below are of the RX and TX used in the recent "over the horizon" NLOS 481THz optical tests. As you can see, not too much complexity involved considering the useful science that results. All parts are inexpensive and readily available. Nothing critical apart from the PIN photodiode and the 280000mcd red LED which I got from Hong Kong via eBay. 100mm optics used at the TX and RX ends.

The 481THz receiver
The 481THz beacon transmitter