Sunday, April 25, 2021

Elad FDM-S3 Again - Problems Solved?

Apparently, the problems I had with connecting to the S3 after a PC reboot or power down, have disappeared! Don't ask me why. It's the same PC, same USB port in use, no updates, nada. It would be only fair to update the article based on these findings. I also tested the FDM-SW2 software, and found it a lot more easy to record 24 MHz to a hard drive than with SDR Console. Still hoping for HDSDR support though.

Here is the revised article.


Saturday, April 17, 2021

Approaching End of Season - Removing Beverage Antennas

Last weekend I started taking down the beverage antennas. The NA season was mostly over, and the reindeer migration was underway, so the 310 beverage and the dual, staggered 340 beverage were reeled in and taken indoor. Asia and Australia are still heard a few weeks, so lowered the 50 beverage and the 80 beverage to the ground, basically making them BOGs.

Today the time was come to collect the 520-metre 50 beverage. It's a fairly easy job on wet, rainy ground because the friction is a lot less. It does weigh a bit though, so a wheelbarrow comes in handy for the 200+ metres transport to the KONG HQ.

The 80 beverage is still out, and will be the prime Australia hunter for the next couple of weeks. It is impossible to take down anyway because the last 30-40 metres of it is covered in a concrete-hard, 2 metres high snow drift.

Looking in the direction of the 50 beverage



Heading towards the KONG HQ


Friday, April 09, 2021

First Impressions of the Elad FDM-S3

I've had the FDM-S3 a couple of weeks, and physically it is a totally different beast than for instance the SDRPlay RSPdx or Airspy HF+. For better - and for worse. Here are my first impressions of the Italian flagship. 



Friday, April 02, 2021

The Bodnar Mini Precision GPS Reference Clock: A Perfect Tool for the Perseus SDR

(Updated May 2021)
Older SDRs aren't very stable. Well, compared to old boatanchors and even newer conventional receivers, +/- 1 ppm is excellent. But when keeping track of the offsets of stations is an important factor in MW DX-ing, we do not want the radios to drift. The Perseus SDR, though a magnificent radio in so many aspects, does drift. The stability vs. ambient temperature is +/- 1 ppm, while current SDRs do a lot better, 0.01 ppm or even 0.001 ppm with an OCXO and GPS reference.

At the KONG site, ambient temperatures routinely vary between 10 and 20 degrees C, and in extreme cases (also this winter), down to almost freezing. The Perseus drifts a lot during these temperature changes. We have seen 6-7 Hz drifting over a 10-15 degrees temperature change. Keeping track of offsets becomes challenging and manual calibration on known stable stations is often impractical.

The Bodnar Mini Precision GPS Reference Clock has gained some fame in the DX and radio amateur world for being a relatively low cost, high accuracy tool for reliable frequency readout. With it, you can insert a reference signal to your SDR.

There is no input for a reference signal in the Perseus SDR though. And since we only sample the MW band, we needed the reference signal to be present within the bandwidth we sample. The signal output from the Bodnar is +6 dBm even at its lowest setting, which would need some serious attenuation of the signal to avoid saturation. And with nine Perseus SDRs, did we have to buy nine devices?

No, we didn't. The nine SDRs are fed from four splitters, one for each beverage feedline. With the high signal level of the reference signal, it is in fact easier to wrap a wire from the signal output around the feedline. Induction rules, and the signal level is a lot lower. So, we still had to buy four devices?

No, we didn't! The reference signal is very strong, and the feedlines physically very close to eachother. So we followed a suggestion on the Jaguar Pro reflector and ended up with having to buy only one! A few turns of wire around each feedline provided us with a GPS reference on 1705 kHz for all our four beverages and nine Perseus.

It should be noted though, that our solution is based on the Jaguar software for Perseus - Jaguar enables us to manually or automatically calibrate readout. It should also be noted that the wire from the GPS is very much "live" when not attenuated, and will produce a signal, in our case every 1705 kHz up through the HF spectrum. 

The device needs a 5V power source, which I found on a spare USB port on one of my PCs. The connection also enables communication with the device itself. The only other requirement is of course access to open sky for the GPS antenna.







Saturday, March 27, 2021

Elad FDM-S3 - Very First Looks

 So I decided to buy one. At 780 EUR + Norwegian VAT I could easily buy three RSPdx for one S3. And probably fit six of not more of them inside the S3 cabinet. But it was intriguing to test a proper 16-bit ADC SDR with HF and FM coverage and 24 MHz sampling rate.

The money drain didn't stop there. To be able to sample 24 MHz, none of my PCs are even close in performance. So I bought a Lenovo ThinkCentre desktop which set me back as much as the S3. The all-cores passmark is 13000-ish so it's reasonably quick.

The S3 arrived two days ago, one day after the Lenovo. I set up the combo at my home here in Tana, where I have no antennas, for testing performance and compatibility. They seem to work very well together. I have been running the S3 with SDR Console at 24 MHz sampling for 30 hours now, with no issues at all. CPU usage is quite stable around 34 %. During IQ recording, the load increases to 40 %.

During the Easter holiday I expect to have lots of time to explore the SDR in depth, including doing the mandatory MW sensitivity measurements. Below some photos from unpacking and first run.

S3 in blue colour, "matching" USB 3 cable + Powerpole DC cable. No PSU supplied but three SMA to BNC adapters were most welcome.



Yikes! Boatanchor!



S3 running with a headless Lenovo ThinkCentre (behind), remote-controlled with the Dell laptop.




Tuesday, March 02, 2021

Winradio G31DDC - Now With SDR Console

July 2010: I received my first Winradio G31DDC from Waters & Stanton in the UK. I was looking for an SDR at least as good, or preferably better than the Perseus SDR, and this was it. Armed with a 16-bit ADC and slightly better sensitivity, it was Winradio's attempt to cater for the DX community rather than professional customers. 

I didn't fancy the graphical user interface though. And what's worse, for one used to making IQ recordings, both live and scheduled, its software failed miserably. First, the IQ files could not be date- and timestamped. Why on earth....? Second, the scheduling option was audio ONLY! Why, oh why.

Later on, the G33DDC appeared which solved these "issues", but at more than double the price. The GUI itself was still not what I wanted, and no third-party software was in the pipeline. Then came the Jaguar software for Perseus, a giant leap for DX-ers who want to schedule, record and analyze IQ recordings. So, both Winradios were sold.

Fast forward to 2021: SDR Console and Simon Brown decided to work on the G31DDC. By coincidence I had a G31 belonging to an estate, waiting to be sold, and decided to wait out Console support. I got a beta version in mid-February, and it worked well, although without an antenna. When I drove to the KONG HQ last weekend I brought the G31DDC with me, and got it playing with a beverage antenna. 

Let there be no doubt: This is a first class SDR. Console is a very good overall SDR software, and the combo works extremely well. Since I DX the MW band almost exclusively, the Perseus/Jaguar combo will remain my favourite setup. But for most DX-ers, the G31DDC + Console combo is hard to beat. Not least because it's an active product from an active manufacturer who is in the radio game for the long run. 

I just had to buy the G31DDC.

And support for the G33DDC is nigh!



Friday, January 08, 2021

6 Watts, 1485 kHz, 2540 km

There's been a few DX tests this season, and rather by coincidence I stumbled upon another one the other day. The IRCA and MW Circle reflectors reported that Mittelwellen-Sender Joe, transmitting from Erlangen in Germany on 1485 kHz, was sending periodic 1000-Hz tones - one second on, one second off.

Now, that sounded like a nice challenge. The first evening I tested I heard the transmission right away at the KONG HQ, and a very good signal at Smøla. DX-ers in Scoland and Ireland also reported the signal. The initial enthusiasm faded a bit when I later learned that the effect was in fact 100 watts, not 6. 

What I hadn't noticed from the reflector posts was that from 17:00 to 05:00 UTC the power is 100 watts, the rest of the day 6 watts. I had been listening in the evening.

So I decided to try again, and focus on the period before Germany's sunrise. I monitored the signal from 04:58 (100 watts), and then at 05:01:35 the relatively strong signal disappeared...almost! A very faint signal was still there, and I got my 6 watts, 2540 km reception! The image below shows the weaker tones above the red line as the signal dropped.

Perseus/Jaguar recording, SDR Console playback

I chose the 540-metre Asia/Pacific beverage antenna for the reception, because its back lobe crosses western Europe. Interference mostly from SER Radio Santander.

More informasjon about Joe can be found here.

Ordinary programming may resume soon, so I don't know for how much longer it's possible to hear the tones 24h. The tone will be broadcast from Midnight to 05:00 (presumably UTC), but at what power I don't know.

I really think this 1000-Hz test should be able to travel quite far at 100 watts. The eastern shores of North America should be possible. At least worth a try.


Saturday, January 02, 2021

DX Test From WCPH Etowah TN 1220 - Heard!

WCPH is a 1-kW day, 109-watt night oldies station in the south-east corner of Tennessee, not far from Chattanooga. The station owner George Hudson agreed with the NRC/IRCA Courtesy Program Committee to set up two two-hour DX tests with their day facility. The first on December 26, the other on January 2, both tests running from 07:00 to 09:00 UTC.

1220 is certainly not the easiest frequency with powerful stations like WHKW Cleveland, CJRB Boissevain and often XEB Cd. Mexico with potentially strong signals. 1000 watts isn't much to compete with. But we know that morse code and sweep tones are extremely efficient methods if you want to reach far.

Reception of the December 26 test was a failure. Geomagnetic conditions were very poor. If I remember correctly the only signal we heard was a very faint CJRB.

Propagation forecasts for January 2 were far more optimistic though. And true enough, at 07:00 we did hear the sweep tones on our Smøla island rigs. Later on, sweep tones and morse IDs were heard at the KONG site, and with quite a bit better signal than Smøla. At KONG, there was little interference except CFAJ fading up a few times, and CJRB/XEB lurking in the shadows.

The distance to Smøla is 6660 km, to KONG 7128 km. WCPH was also heard in Lemmenjoki, Finland, and Scotland. And maybe elsewhere in Europe for all I know.

Many thanks to the CPC and George Hudson for making this opportunity to catch a new station! I hope George is satisfied with how his station got out. A good start for 2021, DX-wise!