First DX Signals Of The New Season - And A Comparison

I rarely hear any Trans-Atlantic DX here in August. My northerly location is of course to blame. Last night though, the ususal eastern North America stations were heard with ok signals, such as 1200-Ottawa, 1500-Detroit, 1510-Boston, 1520-Buffalo, 1540-Toronto and 1600-Boston together with quite a few others (including rather surprisingly Pulse 2 from Huddersfield on 1530). The first signal from Down Under was heard Friday evening with presumed 1620-Sydney with Arabic music.

Tonight's DX was somewhat noisy as there were frequent static crashes from thunderstorms somewhere. This gave me the opportunity to compare how the AGCs of the Excalibur software and SDR-Radio handled the noise. Generally there was a noticeable difference in favour of SDR-Radio. Nowadays with SDR software, AGC settings can be adjusted ad infinitum, but at least when it comes to out-of-the-box settings, SDR-Radio was the winner.

Antenna Preparations II

340-degrees beverage daytime noise level. The peaks are semi-local Russian stations (and the very local  "BV" NDB on 399 at extreme left)

The 340-degrees beverage (Western North America) was put up today. Unlike the other beverages it is lamp cord fed, not Twinax, and while the noise floor is at the same ultra-low level as the 50 and 310 degrees beverages, there are a few local noise peaks though not above -115 dBm. The jury is still out on the question should we replace the lamp cord with twinax.

This Is What I Call A Quiet Location

Actually, I have never experienced a noise level as low as today. China Radio International 1323 is 90 % readable at a signal level of 0.37 uV in AM mode, and 100 % readable at 0.6 uV. It doesn't get much better than this. Beverage 500 meters at 50 degrees, Twinax feed line.

Antenna Preparations

The 50-degrees Pacific beverage was set up last weekend, and erected to an average of 1.2 meters today. I also set up the 310 east North America beverage, but decided to keep the lamp cord feedline for now since the thought of rolling out 175 meters of thick and heavy Twinax was discouraging.

When I connected the 310 there was practically no signal at all. The observant reader will have guessed that the feed line was at fault. I didn't at first, so I spent a few hours in total confusion. This year rodents are exceptionally plentiful, and it appears that the seasick-green lamp cord was mistaken for food by the voles who thrive around the house. So I decided to roll out the Twinax anyway. The endless hours at the gym finally paid off. And the 310 is now in excellent shape, except I have to elevate it from the ground.

I think this calls for a Heineken on the balcony. Still a bit early in the season for any real DX.

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Balanced Feed Line - Replacing Lamp Cord With Twinax

Observant readers will know that last year, we replaced our old coax feed lines (mostly RG-213 and RG-58) with cheap "Lamp Cord". Using balanced feed lines instead of unbalanced proved to be an immediate success in terms of noise reduction and flexibility. The cost was the need to put a 100:50 ohm transformer into the feed line before entering the 50 ohm receiver antenna input. Though if you didn't, you wouldn't lose more than a few dB.

This summer, we purchased two 1000-ft rolls of "real" balanced feed lines, namely Twinax. It is not lightweight and flexible like the lamp cord - actually it's only a bit thinner than RG-213, but well screened and protected from precipitation, salinity, temperature changes and rodents.

A brief test run last evening with the 50-degree, 500-meter beverage proved that Twinax is indeed the best solution. Some unidentified local noise sources were greatly reduced, otherwise the noise picture in general was the same. I also noted that signals coming perpendicular to the 50-degree beverage were reduced substantially. Indicating that the lamp cord compromised the beverage's side nulls. There was a slight improvement in signal levels alongside the beverage lobes as well, but this could be attributed to the Twinax test being done five minutes later than the lamp cord test (with a declining sun).

Summary: The lamp cord is an excellent feed line for beverages (and other antennas as well). The Twinax is a superior feed line.

Lamp cord feed line

Twinax feed line. Murmansk stations on 657, 1134 and 1521 are attenuated compared to the lamp cord. Higher signal levels elsewhere.

Twinax

The Clifton Labs Z1501 Active Antenna - Pt 4 The 3 Meter Whip

This morning I replaced the 1.5 meter whip with the 3 meter whip. On SW, the difference was significant, with my semi-local Radio Rossii 5930 increasing 10-15 dB in gain. On MW however, there was only minor gain improvements as Rossii-657 increased its strength by only 2 dB.

This concludes the test of the Clifton Laboratories Z1501 Active Antenna. I will most likely dismantle it from my Kongsfjord QTH and erect in in a tree outside my apartment in Vadsø. It will be interesting to see how much it will be affected by the usual noise a residential area will produce.

The Clifton Labs Z1501 Active Antenna - Pt 3 Properly Erected

The next step was to find a better location for the antenna. I erected it on a pole around 30 meters away from the house, and prepared the necessary RG-58 coax. Still with the 1.5 meter whip, I mounted the enclosure at around 2 meters, so the total height of the antenna is 3.5 meters. Mounting it higher will increase its gain.

Both the noise level and signal levels improved considerably. As can be seen below, the antenna appears to have  equal sensitivity all the way up to 30 MHz. I didn't compare with the Mini-Whip this time. At the time of writing, 90 minutes after sunset, it seems to work well on MW with a noise floor around -120 dBm.

Weather permitting, I will erect my 310-degree beverage tomorrow. It will be interesting to compare noise floors and signal levels. I will also replace the 1.5 meter whip with the 3 meter whip to see how much gain increases.

Already at this stage though, the Z1501 has proved to be an excellent all-round antenna, both with regards to coverage (since it is omni-directional) and frequency range.

The Clifton Labs Z1501 Active Antenna - Pt 2 Initial Tests

I didn't have enough coax at hand, so for the first test run, the Z1501 was put up with the 1.5 m whip alongside the house wall. Not a favourable position with regards to RFI, but enough to see how (and if) it worked, and to make a brief A-B test with the Mini-Whip.

It has gain all right. I feared that the semi-local Loran C transmitter (250 kW on 100 kHz 14 km away) would make trouble when I connected the Z1501 to my Winradio Excalibur SDR. The Excalibur has no band pass filters or preselectors, so in principle it is wide open.

I was right. I got ADC clipping and needed to attenuate 12 dB to get rid of it. I assume though, that conventional receivers with band pass filters or tracking preselectors will not be affected. Anyway I am used to Loran C trouble, so I have a suite of 100 kHz notch filters, one of which was inserted between the DC Coupler and the Excalibur. Loran C gone.

To compare with the Mini-Whip, I mounted the latter at the same height as the Z1501 enclosure and ran a few tests.

Mini-Whip MW Response 

Z1501 MW Response

The difference in this daytime test (almost no stations audible) is significant. The 1449 Radio Rossii signal is 15 dB higher on the Z1501. But keep in mind that the price tag is at least "15 dB" higher too. It's a bit like comparing a Ferrari to a Fiat 500.

And I still haven't put the 3 meter whip on...

The Clifton Labs Z1501 Active Antenna - Pt 1 The Hardware

Conventional wisdom says that MW DX-ers use beverages whenever they can. And if they can't, they use loops of various sizes and properties. So what about whips? Noooo, serious MW DX-ers don't use whips. Whips are for FM or VHF. Only if nothing else works or is possible to erect (including a five cm ferrite bar), will a serious MW DX-er even remotely think about mounting a whip.

Time to think again. Whips with good performance have been around a while. Many NDB DX-ers have successfully used Roelof Bakker's "Mini-Whip", an excellent proof that size doesn't always matter. I've had the Mini-Whip myself a couple of years, and although it has never outperformed my beverages and QDFA, it is an excellent device.

For quite some time I have wondered about purchasing another whip. This summer I finally decided to go for it - not that I really needed it (and I don't think it will outperform my beverages and QDFA), but I was curious if it could perform even better than Roelof's mini antenna.

The Z1501 is sold with either a 1.5 m or a 3 m whip. I chose both, since it was only USD 16 extra.

The Z1501 is an electric field responding “active” antenna, employing a high impedance field effect transistor input stage to efficiently couple electromagnetic field from a physically short antenna to a low impedance (50 ohms) load. The most effective frequency range is 20 kHz to 30 MHz. The size of the weatherproof enclosure is 114x63x25 mm mounted on a larger mounting flange. It has a female BNC connector for 50 ohm coax feedline.


In-house is a DC coupler which delivers 9-24 VDC to the antenna. It can also be used with other active antennas - I have used the Mini-Whip with it with good results.

Enclosure and mounting flange. BNC out to the left.

Telescoped whips, 1.5 and 3 meters

DC Coupler back panel

DC Coupler front panel with green LED

The Z1501 is bought as a kit or assembled. Knowing how soldering limitations, I opted for the assembled version.

So how does it perform? We will soon find out.

A New Gadget

I recently received this item from the USA. I plan to test this gadget during the coming weekend, so late Friday or Saturday you will know what it is (many will have guessed already) and who made it (probably not that many).

Sorry about the poor photo quality.

StationList - A Killer App For the Perseus

The Perseus SDR was the first "serious" European SDR manufacturer, and soon drew attention to people who wanted to develop their own applications to expand the Perseus software. For the serious MW and NDB DX-er, maybe the best of them all is Jürgen Bartels' Station List, now in version 2.1.1.1.

Why is it so?
Imagine you being on a DX-pedition (or your own home for that matter), and in the course of five days of intensive DX-ing and recording you are stuck with some 2 TB of data. Maybe you have recorded all the TOH and BOH over most of the five days, and some interesting DX in between. Well it was fun doing the DX session, but when on earth will you have time to get through the thousands of potential stations? Let's say there are 100 interesting frequencies, you conservatively record two minutes on the top, two minutes at around five past, and two-three minutes at the bottom of the hour. That's 700 minutes of listening, for checking one single hour! 
Admit it, you're never going to get through all this.

Often, when we check RF recordings, we select one recording, and start listening at the top end, or the bottom end. Now....there was an interesting station on 1290, I must remember that one when I start the next recording. But I don't, do I, because I found an interesting station on 1150 instead and forgot all about that interesting station on 1290. Now, wouldn't it be better if you could stay on 1290 for as long as it took to find out what it was - just change into the next file with one mouse click while keeping the same frequency and at the exact same spot in the playback? To track 1290 throughout the night? Of course it would. And that's what Station List does.

Among many other things.

Actually, the function mentioned above may not even be the main purpose of Station List. Describing Station List is a bit difficult, because aside for monitoring recordings, it is a lot of things. It is a database which interacts with Perseus; you can use a database to tune the Perseus, or if you tune the Perseus, the database of choice follows it. And you can import databases, such as KOJE, FMLIST, MWLIST, LA MW-LIST, EIBI, TBL and Nagoya. It is a tool for scheduled RF recordings. It is a log program. It is a tuning program. It is a server program. It is a server monitoring program. It is indeed a lot of things. Actually it is so much, it's impossible for me to write a comprehensive review or description. But it makes checking your 2 TB of RF recordings a lot quicker and a lot more fun than the traditional way. The pictures below may hopefully serve as an illustration.

I will test the Scheduler later on.

Works on XP, Vista and Win7 systems.

SDR-RADIO - An Alternative to Spectravue

As owners of RF Space SDRs will know, their native software Spectravue, now in version 3.21, offers a powerful yet rather convoluted graphical user interface. For some time, SDR-RADIO.com has offered an alternative GUI, now in version 1.3. I decided to test SDR-RADIO with some old SDR-IQ files on my system. Later on, I plan to test the GUI "live", with an SDR-IQ.

SDR-RADIO.com claims to be a Windows console for SDR receivers and transceivers. It is designed for the commercial, amateur radio and short wave listener communities to provide a powerful interface for all SDR users. Especially interesting for many DX-ers is that it provides an alternative to Spectravue for running RF Space SDRs. Not that Spectravue is a poor program. Its basic appearance is simplistic, with most if not all of its functions hidden in menus. SDR-RADIO.com moves most of these functions up front and adds quite a bit of user friendliness in the process. I will not go into detail about the software, since the possibilities are outlined at SDR-RADIO.com's home page.

SDR-RADIO.com has a resizeable window, or can be run in Full Screen mode. The illustrations below show how they appear (note that I have selected the Zoom function at playback). The Full Screen mode appears clean and uncluttered with the basic controls available, and with the all-important date and running time available.

However, for selecting a file or other input you need to use the resizeable window mode. With a lot more information available, space for the waterfall/scope is limited unless you have a very large display. Otherwise, SDR-RADIO.com offers a wealth of radio-related functions, such as the HFCC database, Solar data, a world map with the sun's position, and options enough to tailor-suite your GUI from here to eternity. One example: You can "design" your own bandwidths, and assign them to one or more modes.

Playing back SDR-IQ files worked well. The console has three "VFO"s which can be configured independently, and an MP3 recorder using 32 kbps, 8 kHz mono. Now, this is one function where I wanted some options, such as being able to record wav. Apparently, this is not possible.

And of course, you can record a chunk of the RF spectrum for later analysis - the holy grail of the MW DX-er.

Very important for RF recording, the console has an Outlook-type Calendar with extensive recording scheduling available. However, you need to configure each recording session within one day independently; you can't plan a batch of recordings within 24 hours since the shortest recurrence period is 1 day. That calls for time consuming editing if you plan to record every full hour and every half hour for a night. Hourly recurrence should have been available as an option.

While I haven't tested SDR-RADIO.com very extensively, it does indeed look like an interesting alternative to Spectravue. Remote control is said to be one major feature with SDR-RADIO.com that I haven't tested at all.