SAQ and electro-mechanical VLF receiver

[Brian Howie]

I was reminded of this when chatting to David GM8ARV on the way to the
Galashiel Rally.

"The transmission is on 17,2 kHz CW.on October 24th 2019

Startup of the transmitter around 16.30 UTC Transmission of a message at
17.00 UTC

You can also watch a live video stream of the
transmission on https://www.alexander.n.se.

No QSL-cards will be given this time and no List of Reports will be
constructed but we accept shorter Listeners Report to
e-mail in...@alexander.n.se.

Sound card receiver here:-

https://sites.google.com/site/sm6lkm/saqrx/

I also mentioned an electro-mechanical receiver for VLF
It's by Jim Moritz M0BMU

http://www.wireless.org.uk/mechrx.htm?LMCL=nlmy3_

it uses a motor-generator to make a BFO and a saturable reactor mixer.

Brian GM4DIJ
--
Brian Howie

[Brian Reay]

The mechanical receiver is interesting.

It set me thinking how you could improve the frequency stability ( a
problem Jim mentioned in his write up). A fly wheel was one idea but, while
that should reduce some frequency shift, it would also introduce tuning lag
effects. I suppose you could make it complex and have a move the mass
towards the centre somehow when tuning and towards the circumference when
the required frequency is found but that is probably overly complicated.

May be just having a variable governor and using that to control the
spreed, relying on the mass to provide the angular momentum to maintain a
constant RPM.

[Brian Howie]

In message <cXNTeHMM...@b-howie.co.uk>, Brian Howie
<br...@b-howie.co.uk> writes

The transmission was aborted

"AlexanderSAQ Three tries to start but overload protection is tripping"

Shame as I had the rx kit all working. 5ft loop and SAQ Panoramic VLF Rx
V 0.98 I could receive at decent strength.

18300 KHz HWU Saint Assise/Rosnay,
19600 KHz GQD/GBZ Anthorn
22100 KHz GQD/GBZ Anthorn/Skelton
23400 KHz DHO38 Rhauderfehn, Germany

Next time.

[David Taylor]

Interesting, Brian. I was also disappointed, but checking this morning:

18.3 kHz - nothing, but in a spectrum of interference
19.6 kHz - carrier?
22.3 kHz - nothing
23.4 kHz - carrier?

Those where I could detect carrier, there wasn't any obvious modulation.
I think your setup was much better than mine!
--
Cheers,
David
Web: http://www.satsignal.eu

[Brian Howie]

In message <qotuo4$km4$1...@dont-email.me>, David Taylor
<david-...@blueyonder.co.uk.invalid> writes

The data signals are quite distinct- roughly 20dB above the noise.
It took a a bit of fiddling with earths to get rid of interference . The
loop is outdoors and is 7 turns in a shield . There's an earth spike
beside the loop. I could maybe improve it with a preamp at the loop or
a transformer. I've got till Xmas

Brian
--
Brian Howie