SAQ Grimeton Transmission on July 4th

[mickm3for]

Ok here in Kent home brew 1mtr loop into a converter using AR88 rx as second if
Mick

[mickm3for]

this is the link to a sdr that covers 17.2 khz http://websdr.ewi.utwente.nl:8901/

[Restoration73]

OK here at present, converter used with FT-840.

[Nymrod121]

Blimey. It's like having an RA1772 built in to my smartphone ... "what fun!"

Guy

[Andrew2]

I was about to give up but then a carrier came on at about 09:45 and soon began sending CQ's. Shortly before 10 it went silent and then began tuning up followed by the usual CW. I didn't bother trying to read it. It was a good solid signal, about 10 dB stronger on my homebrew LF loop than on the standard Wellbrook.

[AdrianH]

Picked it up with my 20 meter dipole and Palomar VLF converter to my old FT902DM, better than I expected.

Even decoded some of it on my old Velleman kit when I remembered I had it. 12:00 UTC that was.
Adrian

Got it here using a Wellbrook and RSP-DX.

[raditechman]

Received in SW London long wire aerial, SDR Play receiver and SDR Uno software.

John

[Pfraser]

Originally Posted by Dave757

Hi Ian,

Well, I just managed to hear the callsign repeated two or three times at the end of the main transmission, and I could hear the odd character during the start up and main transmission, but I am fighting a losing battle with noise at over S9!

Using a Datong VLF converter feeding a Yaesu FT857 in the narrow CW position with the DNR engaged, and a 25 foot or so wire antenna indoors suspended from end to end of the bungalow! (My tenancy agreement doesn't allow external aerials). I really must make up a loop for VLF.

Located on the east coast of Norfolk, near Gt Yarmouth, so a bit closer than you!

Kind regards
Dave

I don't want to get you in trouble...but how about a very thin wire outdoors, even if only temporary? Or something crafty involving a washing line, or an arris rail along a fence.

I saw strong cw-type signals on the Twente SDR's S-meter. The far LF end of the waterfall display was rather cramped and hard to read!

[William78]

I too received the transmission at 12.00 utc on a SDRplay RSP1a and a 25m long wire.

It was a weak signal but I could still copy it. Next time I will try an active loop, (yet to be made).

William

[Aub]

I watched the recording on the internet. Very interesting.

Aub

[Restoration73]

The easiest way to make a long wire resonant at 17.2kHz is to insert an inductor in
series with the converter or sound card. I used a decade box to establish that a
series value of 300-400mH is needed. The inductor can be made using a ferrite rod
with about 500 turns of thin enamelled wire. If the coil can be slid along the rod the
optimum value can be attained.

[Dave757]

[QUOTE=Pfraser;1387767]

Originally Posted by Dave757

Hi Ian,

Well, I just managed to hear the callsign repeated two or three times at the end of the main transmission, and I could hear the odd character during the start up and main transmission, but I am fighting a losing battle with noise at over S9!

Using a Datong VLF converter feeding a Yaesu FT857 in the narrow CW position with the DNR engaged, and a 25 foot or so wire antenna indoors suspended from end to end of the bungalow! (My tenancy agreement doesn't allow external aerials). I really must make up a loop for VLF.

Located on the east coast of Norfolk, near Gt Yarmouth, so a bit closer than you!

Kind regards
Dave

Hi,

Many thanks for suggestions. The main problem here is no back garden, and a postage stamp of a front garden, which sadly contains the main source of
the noise , - a telegraph pole carrying phone, broadband and mains.

So tend to use indoor antennas, but the main problem seemed to be that the signal was masked with noise, so a loop for VLF would have been rotatable
to minimize that.

Best 73
Dave

[dsergeant]

Originally Posted by Restoration73

The easiest way to make a long wire resonant at 17.2kHz is to insert an inductor in
series with the converter or sound card. I used a decade box to establish that a
series value of 300-400mH is needed. The inductor can be made using a ferrite rod
with about 500 turns of thin enamelled wire. If the coil can be slid along the rod the
optimum value can be attained.

Is that 'microhenries'? 300 millihenries sounds incredibly large.

Not had a chance to play with SAQ in recent years but did pick it up some ten years ago on my Datong UC1.

73 Dave G3YMC

[Restoration73]

17.2kHz is in the audio range. The inductance of a standard LW coil ca 200kHz is 4mH.

In the mid 1980s I bought a Marconi Atalanta, and I received GBR on 16kHz (QRT) my
first experience of vlf reception.

[Andrew2]

Given the meagre capacitance to earth of yer typical short-ish 'longwire', I'd be surprised if even 400mH was enough.

[turretslug]

A good case for trying a quick finger-in-the-wind sanity-check- given a particular capacitance, halving the frequency implies quadrupling the inductance for resonance. If 4mH is appropriate for 200kHz, then 16mH would suit 100kHz, 64mH for 50kHz and 256mH for 25kHz...., so 400mH would seem to be a) not mad and b) the right ball-park at least.

I managed to miss the transmission (again) but have heard it in the past with a very simple home-brew up-convertor (LPF into NE602, 4MHz LO) and 40ft wire into an FRG100 with 500Hz filter. Definitely a random wire, not a "long wire", a long wire at 17.2kHz would be difficult to accomodate in, well, Great Britain!

[kellymarie]

I'm pleased to say I heard the 12:00 GMT transmission i watched a bit of the youtube coverage before going to the shack I've got no interweb in the shack. Also could here multiple FSK transmissions around the same frequency VLF is a busy place

[kellymarie]

I just checked again and i could here those pips on 175 kilocycles and thistime i could here the 2 strings if pips a definite pitch change i think this time I was lucky that there was a relatively low noise level apart from a bit of thunder static still no clue where they emanate from but I'm sure eventually someone will find out