Category Archives: VHF

Links, News, Uncategorized, VHF

New 4 metre web SDR IN South herts.

John G3VHH notes we have a new 4 metre web SDR available to us covering 69.492 – 71.028 MHz

http://81.111.70.181:8091

IP address may change so look at http://websdr.org/ for a definitive address. Text is “4 Meter WebSDR Located in south Hartfordshire UK using a RTL Dongle”. Antenna is a 4 metre quarter wave ground plane.

Many thanks to John and Steven M0XVT for making this available.

73

John G4RDC

VHF

Check out FT8 on 6 metres for Es activity

I’m seeing tons of Sporadic ‘E’ activity (Es) on FT8 digi mode on 6. Running wsjtx. 50.313MHz.

Would be interested if anyone sees a double-hop – or further – as per Chris Deacon’s talk. Paths open to Finland this morning so maybe the JA path will open up.

Also how it compares to 10m, 4m, 2m. Haven’t seen any FT8 on 4m.

https://physics.princeton.edu/pulsar/k1jt/wsjtx.html

What’s interesting is WSPR seems dead on 6 but FT8 is hopping.

Ant is slim jim strung from a tree; motorola mc micro + 21.4MHz IF  tap into a funcube dongle. wsjtx-1.9.0-rc3 on Ubuntu Linux 17.4 on Dell M4400 2.8MHz Core2 laptop. Rx only. For now…

Very strong signals so Ian NXJ won’t be getting much sleep in the shack. With those sort of signal strengths, FM 51.51MHz calling will open up.

Events, VHF

meeting 26th April “UK Six Metre Group – the magic band” by Chris Deacon G4IFX

Chris Deacon G4IFX of the UK Six Metre Group (UKSMG) will be with us for
all things 50MHz including how to work Dx on 6 and how best to take
advantage of the forthcoming Sporadic ‘E’ Season. We hope!

Venue: Woodford Park, Woodley, 8pm as usual, Thursday 26th April.

For me, it’s a fascinating band sharing properties of HF and VHF. It’s
also fun waking Ian G8NXJ up by putting a call out on 51.51MHz FM when
he’s having a nap in the shack.

For full license holders, you do have to be a bit careful with that as
we are only secondary users in the ‘top end’ of the band (51MHz-52MHz)
and limited to 100W rather than the ‘usual’ 400W. For me, 5W from Earley
is usually enough to wake him. Also repeaters GB3AM (50.84/77Hz) and
GB3FX (50.81/82.5Hz).

Talk suitable for all levels of expertise. Newcomers most welcome.

http://www.uksmg.org/landing.php is the UK Six Metre Group website so
you can get your questions ready beforehand.

Coffee, tea and biscuits will be in plentiful supply.

73

John
G4RDC

Events, Talks, UHF, VHF

talk “Height Matters” by Mike Naylor G4CDF, 22nd February 2018 8:00pm

Height Matters – by Mike Naylor G4CDF on Thursday 22nd February 2018 at 8:00 PM – 10:30 PM Woodford Park Leisure Centre, Haddon Dr, Woodley, Reading RG5 4LY

During a recent shack tidy Mike G4CDF encountered many QSL cards from his student days. On looking though them Mike was surprised by what was achieved (mainly VHF/UHF I believe) using the presumably modest station set up at the time. This lead him to thinking about how the location it’s associated attributes affected communications.

No doubt with a splash of reminiscence and a good helping of nostalgia, this should be a very interesting talk, and I am sure we will all learn something including some details on to build a station that can regularly communicate over distances of several hundred kilometres, the effects of antenna size and height, and the effect of local terrain, power level and local noise levels.

We look forward to seeing you there.

[New year’s resolution diet busting refreshments will be served – G4RDC]

73

Simon, M0ZSU, RADARC

Events, SHF, Talks, UHF, VHF

meeting Thursday 8th February: Noel Matthews‏ G8GTZ : The Portsdown Digital Amateur Television Project

On Thursday 8th February, we welcome back “Professional radio amateur” Noel Matthews‏ G8GTZ to tell us all about the Portsdown Digital Amateur Television project. You may recall his last talk on cubesats where they used magnets to orient the craft in orbit…we all liked that.

Venue: Woodford Park Leisure Centre, Haddon Drive, Woodley, RG5 4LY
Time: 8pm

So…continuing the theme of elegant engineering:

“The Portsdown DATV project provides an easy way to “get on air” with Digital ATV at relatively low cost. The Portsdown system enables amateur radio operators with little or no knowledge of Digital ATV to construct the hardware elements, load and configure the software and use the system to send live Digital ATV signals across town on their existing aerials. It includes the new Reduced Bandwidth modes and the ability to transmit to local repeaters using the more traditional 2 and 4 Msymbol DATV modes. Frequency coverage of 71 MHz, 146 MHz, 437 MHz and 23cms bands.”

Our very own Simon M0ZSU is also involved with the project and is
building one himself.

Noel and Brian Coleman G4NNS (who also gave us a talk on mapping
galaxies from your back garden using hydrogen line astronomy iirc!!) are now global super-stars after their appearance on Michael Portillo’s “Great British Railway Journeys” BBC programme using the Goonhilly 32m GHY6 dish for 3.4GHz and 5.6GHz EME operation.

Now RADARC members aren’t backward in coming forward so perhaps we can extract some stories about that too. There must be some.

If we ask nicely, Noel might also tell us about his web sdr which I find
very useful for monitoring:

http://farnham-sdr.com/

Tea/coffee/biscuits (many thereof) as usual.

73

John
G4RDC

Member stories, Satellites, VHF

ISS SSTV 2m FM transmissions this weekend

This weekend, ARISS is celebrating its 20th anniversary with a series of SSTV transmissions from the ISS – International Space Station.

Transmissions will be on 145.800 FM in PD 120 or PD180.

These should be easily receivable on a handheld tuned to 145.800 with anything better than the stock whip. Last time around they were loud! A 3 element tape measure yagi will work very well for this, and it’s not much effort to knock one together. Full quieting signal should be achievable.
Images can be decoded live during the passes on a smartphone using, for example, “SSTV Slow Scan TV” by Black Cat Systems for iPhone, or “Robot36 – SSTV Image Decoder” on Google Play for Android. A cable will help, but holding the mic up to the HT speaker should work okay. Alternatively recording the audio through whatever means will allow you to play around decoding later.
Passes for the weekend can be found on http://www.heavens-above.com as well as other sources. Be sure to set your location. Some key passes:

Thu 23:23:21
Fri 00:58:35
Fri 22:32:15
Sat 00:06:25
Sat 23:14:23
Sun 00:50:21
Sun 22:22:34
Sun 23:58:03
Mon 01:34:30

Event is scheduled to end at 18:00 UTC on Monday 24 July.

Most of the passes this weekend are visible, so assuming no cloud, antenna pointing shouldn’t be a problem 🙂
 
Most favourable pass taking into account the time looks like Sat 23:14:23 BST.
 
For those of you who have not spotted ISS in the night sky as yet, at its peak it is second only in brightness to the moon in the night sky, appearing as a solid bright white point typically low in the south-western sky from the UK, appearing to move across the sky about the same speed as an airplane at altitude. At its highest point, on a high pass, it really is hard to miss – easily brighter than Venus or Jupiter. Some passes it will fade into shadow, some it will pass across the whole sky brightly reflecting full sunlight, well into the late night down here.
 
If the same format is followed this time around as last, there will be 2.5 ish images per pass with a few tens of seconds gap in between, with no carrier.
 
Happy sat spotting…
Update
In the end I slept through most of the passes! However here’s the one image I did capture:
I put together a simple cable to connect my Wouxun handy to my iPhone based on this circuit,  used an inexpensive Nagoya NA-771 whip, and for aiming, I listened for ISS on a second handy on its stock antenna, held closely and parallel to the Wouxun, broadside to ISS. Almost perfect copy, up to at least S6 or so. Great fun!
Did you capture anything? Tell us @MX0AAA!