Published at 13:16 on 6 November 2011
My latest Voice of Korea recording may be found here.
The audio quality is sort of iffy in this recording, but it’s actually the best signal of any of the times I’ve thought to tune in recently. Trans-Pacific propagation has been sort of crappy recently; this has adversely affected my ability to receive Australia and New Zealand as well.
Voice of Korea has less to say for themselves in this recording than they do in some of my earlier ones. Starting several months ago, the amount of spoken word programming declined greatly, to be replaced by programming consisting mostly of music. There’s actually more spoken material in this recording than there has been in some other recent broadcasts, so maybe this trend is reversing itself.
Perhaps of particular note is the piece on wind power at the end of the transmission, which in a marked departure from virtually all Voice of Korea programming, appears to have nothing to do with praising the “Great Leader”.
As usual, the “news” is dominated by whatever the “Great Leader” has done recently (this always leads); mention of any favorable things said by foreigners about the DPRK also figures prominently. The latter is frequently from those belonging to insignificant Stalinist splinter groups, or items in a foreign paper which are actually a paid ads taken out by the DPRK foreign ministry.
Hopefully someday soon I’ll take another camping trip and be able to furnish something recorded in a more RF-quiet, rural location.
Published at 18:14 on 25 October 2011
I have learned very recently that at long last Voice of Korea has an official web site. Unfortunately for those who wish to stream audio, the links that let one do that are currently not working. However, that will probably get fixed in the not-too-distant future, meaning that there will at long last be an alternative to shortwave for those who want to listen to official North Korean propaganda.
Until then, I plan on recording their broadcasts off shortwave, as time and propagation conditions allow.
Published at 18:01 on 25 October 2011
It’s a coaxial grounding block of the type cable TV companies use at service entrances.
Well, actually it’s not: the ones the cable companies use are made by reputable companies and work properly. This one is made by some anonymous factory in China and fails to grip the center conductor of the coax properly, causing intermittent connections.
This is something I wasted about two hours on this afternoon (I blamed myself for failing to install the F connectors on the coax properly at first, and only gave up on this theory after the connection was still intermittent even after my third such attempt).
Eventually, such repeated failures, combined with the fact that I’m no novice on installing RF connectors on coax, and combined with how the item was discounted as a discontinued item (no returns accepted) made me suspect the guilty party. Apparently, I am not the first to have trouble with this item, and the store doubtless got tired of the endless string of returns on it and decided to discontinue stocking the part.
Thankfully, I seem to have resolved the issue without an extra trip to the hardware store for a properly-made grounding block. (I shimmed the faulty center terminal with some bits of thin copper wire.) But it’s a lesson that sometimes what appears to be a good deal (I was pleased at the price discount) is too good to be true.
Published at 14:46 on 25 October 2011
Well, it’s basically all finished (except for putting some tools away), and I must unfortunately report that the remaining work I did today accomplished only a modest improvement in the antenna’s performance. There does appear to be less influence on reception from indoor noise sources, but it also appears that the source that makes the noise floor below about 11 MHz so high is elsewhere in the neighborhood. That said, the improvement at 11 MHz and above is nothing short of astounding.
I do have two notes to add to the instructions John Doty wrote nearly two decades ago:
- Weatherproof metal project enclosures (“miniboxes”) are not so easy to find locally, and many of the mail-order sources for them have onerous minimum orders. My solution was to purchase a metal, outdoor-grade electrical box, spare plug (they all tend to come with three holes, and plugs for two), and cover plate and use that for an enclosure. Because one of the holes is on top of the box, I used a liberal amount of Coax-Seal inside the box to help ensure moisture cannot enter. I put all connections on the bottom of the box to minimize the chance of water ingress.
- The 300:75 ohm TV matching transformer I took apart had a ridiculously small ferrite core in it. Even if I used the recommended 40-guage enameled wire (which is annoying to use because it breaks so easily), I see no way I could ever get a total of 40 windings around it. I ordered a ferrite toroid (Core F-50, Ferrite Mix 61) from Palomar Engineers (they have no minimum order and shipped my order very promptly) and used that. Instead of 40-guage wire, I just bought the set of 3 spools of magnet wire that Radio Shack sells, and used the medium size for the 10-loop winding and the smallest size for the 30-loop one.
Published at 09:31 on 25 October 2011
I have thought about constructing the shortwave receiving antenna described here for many years, but never got around to it (until now) because it always sounded like an awful lot of work.
Well, it is an awful lot of work. At least several times as much work to build as any other shortwave receiving antenna I have ever erected. Not to mention a fair chunk of change — I’d estimate I’m out about $200 in materials cost for the thing.
But my preliminary tests — done even before all the noise-suppressing features have been completed — indicate that the thing really works. In addition to being by far the most difficult and expensive shortwave antenna I’ve ever had to deal with, it is also clearly the best.
I am copying Shannon VOLMET on 13264 kHz as I type this entry on my computer in an urban Seattle neighborhood. This is a low-powered signal which must take an unfavorable (i.e. polar) propagation path to reach me, and I had extreme difficulty receiving it even twenty years ago when RF noise levels were much less than they tend to be today. Yet I tuned it in this morning on my first attempt with my incomplete Doty antenna.
Currently, the biggest fault of the thing is that I am still getting a lot of RF noise below 11 MHz. I’m hoping that’s merely a result of my not having buried most of the cable run between me and the antenna base yet (only about 1m of the cable is buried right now). At 11 MHz and above, the signals are unbelievably quiet for an urban location. They’re not at rural standards, mind you, but I am able to copy an S1 to S2 signal from Ireland, which to reiterate is pretty darn good indeed.
Hopefully I’ll be reporting further improvements tonight when the antenna is completed.
Published at 19:44 on 22 October 2011
Finally got around to recording another complete broadcast of Voice of Korea this evening. Yes, it’s in English (albeit accented and with muddy audio), in case you haven’t listened to my prior recordings of this broadcaster.
Actually, I’ve made some other recordings as well, but most of them got walked on by the dimmer switch in my housemate’s torchiere lamp. As of this week, that device’s propensity to spew unwanted RF has been muzzled with a ferrite bead on its power cord. Add that to the new antenna I am working on, and hopefully I will be able to make more such recordings from the comfort of home.