SAQ Alexanderson Transmission Tomorrow Monday.

Time for another transmission on the very long waves form the Alexanderson alternator transmitter at Grimeton, Sweden.

The transmitter is only operational a few times a year on 17.2 kHz. Yes, you read right: kHz. 

Tomorrow the schedule looks as follows:

15:00 CET (14:00 UTC): The transmitter hall at World Heritage Grimeton Radio Station is opened for visitors.Transmission & YouTube Live stream
15:25 CET (14:25 UTC): Live stream on YouTube begins.
15:30 CET (14:30 UTC): Startup and tuning of the Alexanderson Alternator SAQ.
16:00 CET (15:00 UTC): Transmission of a peace message from SAQ.

I have once before listened to this kind of transmission. The mode is Morse code (CW) with a moderate speed.

For reception I used my old AR7030 receiver. Officially it covers down to 30kHz, but it is working nicely from about 15kHz. The receive antenna used was an E-probe (a.k.a Mini-Whip or PA0RDT) antenna in the garden. Signals were solid copy. A friend of mine uses an HF ground plane antenna, and that works nicely for him in a quiet radio location.

I think I need to try again tomorrow.

Ground connection for the Mini Whip. RX Test.

 I have a ground rod on the Mini Whip now. Not too far into the ground, about 60cm/2ft. Hammering a 2m (8.5ft) ground rod is tricky without the right tools ;)

The results are interesting:

A relatively detailed review was done today, by dialing slowly through the bands. Starting downwards from around 18MHz indicates that the sensitivity/SNR has improved reception on frequencies from about 1.8MHz up to 18.2MHz, maybe higher.

Medium wave is not bad, with signals on essentially every channel in the whole band, with a reasonable SNR, probably increased sensitivity.

NDB band appears noticable worse wrt SNR, possibly partly due to overload from MW stations in the evening, but noise level seems to have increased.

LW seems OK, not spectacular.

VLF (<100kHz) seems more sensitive, but with more noise. possibly due to overload of the RX. 

A different Mini-Whip with a real whip antenna (1 - 3m long) might improve sensitivity on VLF/NDB bands, but should probably have a low pass filter with a 3dB cut-off frequency of 530kHz. Because a thin whip mounted low is not too visible I might add this to my antenna farm, just to see how it works. If it works well I can make a permanent installation.

Because the Mini Whip is very broadband it may be an advantage to make some filters in any case, possibly as follows:

Low pass with 150kHz 3dB point, for the 136kHz amateur band and "VLF" reception.

Band pass with 150kHz high pass and 530kHz low pass, mainly for the NDB/marine bands and 472kHz amateur band.

MW band pass with 530kHz high pass and 1700kHz low pass.

MF band pass with 1700kHz high pass and 3MHz low pass, mainly for the 1.8MHz amateur band.

HF band with 3MHz high pass filter.

If I get all working nicely I may make a (set of) distribution networks, possibly with switches for the different receivers.

Yes, I like monitoring a lot of frequencies I do have some receivers, everything from purchased amateur equipment to portable transistor radio(s) with external antenna input(s), and, of course some SDRs, and some simple monitor receivers (e.g. a Pixie kit for 40m), and some that I may build. At some time I have been monitoring (audio or data) on 14 different frequencies simultaneously, part of it as monitoring propagation, and I expect this record to be beaten ;)

This is also part of my intention to make a contact on as many bands as possible with (at least partly) home made equipment.

Another Receiver on the Mini-Whip. VLF Reception.

 For a few days I was using my old FRG-100 with the Mini-Whip. The receiver appears to have a rather wide IF filter, meaning that I could hear a carrier all the way through zero-beat (part of the other sideband audible) Not good for listening to AM signals.

Also the lowest frequency I can receive with the FRG-100 is 130kHz. I would like to listen to lower frequencies.

Enter an old AOR AR-7030 I have. I think, according to the specification, the receiver covers 30kHz to 32MHz. Very nice, even if I wanted to test it on a lower frequency. Actually, the AOR frequency dial goes right down to 0kHz. Well not really. on the very lowest frequencies it is totally deaf (no surprise).

Tuning upwards with the Mini-Whip connected the noise starts coming up around 10 - 12kHz. Now it gets interesting. The lowest frequency signal I could receive (until now) is on 16kHz (origin unknown). This means that I should be able to receive the SAQ transmitter from Grimeton, Sweden, next time it has a transmission.

Further, the filters in the AR-7030 are clearly better than those in the FRG. Mounted in this RX are IF  filters with bandwidths from 2.1kHz up to 9.5kHz, in several steps, and also tone controls for bass/treble. There are even better filters in my transceivers, but those have a lower frequency limit of 30kHz or more.

Never the less, VLF signals from as far away as Grindavik, Iceland on 37.5kHz were heard in the day time. Strictly speaking not VLF, but definitely a nice reception. This is a data signal that I did not attempt to decode.

The station in Cutler, Maine (US) was not audible with this set-up, but then again, the antenna is not yet optimized for lowest local noise level. The weather and other activities have been in the way of connecting a ground connection to the antenna. and other steps.

Tuning up through the band, all the way up to 518kHz NAVTEX frequency I now come across a lot of signals. In particular I now hear more NDBs (non-directional beacons used for navigation) in the 300 - 500kHz range, along with other signals of unknown origin (to me at least)

One surprise was a signal on 505kHz:

OK0EMW in JN88ks running CW identification (with Locator) and some QRSS, too.

This must be a remnant of the activity that was allowed on experimental basis on the "old" 500kHz band. I was not aware that there was any activity there any more. Apparently the (QRSS) etc beacon was allowed there those years ago, and the permission has not been revoked.

There is much more to do regarding MF, LF and VLF reception. One thing is to test if I can really hear the SAQ transmission next time it will be active.

Another test should be using my IC-7600 for reception on LF/MF. With the much better (DSP IF) filters reception of many more NDBs and other signal should be possible. There is a lot of noise in that part of the band, so every improvement of the receive side will count. Also, a set-up with a low frequency SDR should be done. The first SDR experiment should be with the RTL-SDR in direct sampling mode, then maybe later I will get a more suitable SDR, also for those frequencies

For the lowest frequencies a test with a computer sound card should make reception up to 24kHz possible, maybe even up to 48kHz with 96kHz sampling.