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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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4th Jul 2021, 11:58 am | #21 |
Heptode
Join Date: May 2015
Location: Chatham, Kent, UK.
Posts: 965
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Re: SAQ Grimeton Transmission on July 4th
Ok here in Kent home brew 1mtr loop into a converter using AR88 rx as second if
Mick |
4th Jul 2021, 12:21 pm | #22 |
Heptode
Join Date: May 2015
Location: Chatham, Kent, UK.
Posts: 965
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Re: SAQ Grimeton Transmission on July 4th
this is the link to a sdr that covers 17.2 khz http://websdr.ewi.utwente.nl:8901/
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4th Jul 2021, 12:54 pm | #23 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: SAQ Grimeton Transmission on July 4th
OK here at present, converter used with FT-840.
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4th Jul 2021, 1:04 pm | #24 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,052
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Re: SAQ Grimeton Transmission on July 4th
Blimey. It's like having an RA1772 built in to my smartphone ... "what fun!"
Guy
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"What a depressingly stupid machine." [Marvin: HHGTTG] |
4th Jul 2021, 1:04 pm | #25 |
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
Posts: 2,038
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Re: SAQ Grimeton Transmission on July 4th
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.
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Andy G1HBE. |
4th Jul 2021, 1:07 pm | #26 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,573
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Re: SAQ Grimeton Transmission on July 4th
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 |
4th Jul 2021, 1:18 pm | #27 |
Guest
Posts: n/a
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Re: SAQ Grimeton Transmission on July 4th
Got it here using a Wellbrook and RSP-DX.
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5th Jul 2021, 8:34 am | #28 |
Heptode
Join Date: Feb 2007
Location: West London, UK.
Posts: 867
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Re: SAQ Grimeton Transmission on July 4th
Received in SW London long wire aerial, SDR Play receiver and SDR Uno software.
John |
5th Jul 2021, 10:42 am | #29 | |
Pentode
Join Date: Sep 2018
Location: Devon, UK.
Posts: 152
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Re: SAQ Grimeton Transmission on July 4th
Quote:
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! |
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5th Jul 2021, 3:12 pm | #30 |
Triode
Join Date: Oct 2007
Location: Warrington, Cheshire, UK.
Posts: 26
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Re: SAQ Grimeton Transmission on July 4th
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 |
5th Jul 2021, 6:10 pm | #31 |
Nonode
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 2,039
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Re: SAQ Grimeton Transmission on July 4th
I watched the recording on the internet. Very interesting.
Aub
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Life's a long song, but the tune ends too soon for us all. |
5th Jul 2021, 6:24 pm | #32 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: SAQ Grimeton Transmission on July 4th
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. |
5th Jul 2021, 6:48 pm | #33 | |
Heptode
Join Date: Apr 2009
Location: Scratby, Norfolk, UK.
Posts: 651
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Re: SAQ Grimeton Transmission on July 4th
[QUOTE=Pfraser;1387767]
Quote:
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 |
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6th Jul 2021, 6:42 am | #34 | |
Octode
Join Date: Mar 2006
Location: Bracknell, Berkshire,UK.
Posts: 1,175
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Re: SAQ Grimeton Transmission on July 4th
Quote:
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 |
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6th Jul 2021, 8:53 am | #35 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: SAQ Grimeton Transmission on July 4th
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. |
6th Jul 2021, 10:43 am | #36 |
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
Posts: 2,038
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Re: SAQ Grimeton Transmission on July 4th
Given the meagre capacitance to earth of yer typical short-ish 'longwire', I'd be surprised if even 400mH was enough.
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Andy G1HBE. |
6th Jul 2021, 11:36 am | #37 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,400
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Re: SAQ Grimeton Transmission on July 4th
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! |
6th Jul 2021, 1:51 pm | #38 |
Pentode
Join Date: Sep 2020
Location: Weymouth, Dorset, UK.
Posts: 135
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Re: SAQ Grimeton Transmission on July 4th
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
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6th Jul 2021, 6:13 pm | #39 |
Pentode
Join Date: Sep 2020
Location: Weymouth, Dorset, UK.
Posts: 135
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Re: SAQ Grimeton Transmission on July 4th
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
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