GB0SNB/MX0SNB/M0SNB - Kelvedon Hatch Secret Nuclear Bunker

///////////////////////////////////////////
SSB AFS Contest

Posted: 14 Jan 2017 01:23 PM PST
http://www.gb0snb.com/wordpress/2017...b-afs-contest/


With snow on the ground and the sun in the sky it must be time to do some
winter contesting. This weekend members took part in the RSGB affiliated
society SSB contest, this takes part on 7 and 3.5 MHz from 2 till 6 PM.



With a small amount of snow on the ground, and ambient temperatures around
+1C we opted for the inside operating position. The station comprised of an
Icom 7600, Expert 1.3KFA solid state linear and a doublet antenna at 30m on
the bunker tower.

Band conditions on 7 MHz only supported long skip with some good signals
from Scotland and Ireland, although after a short while even these
distances proved difficult. The maximum usable frequency had moved down to
4 MHz, and so a switch to 3.5 MHz was required.



A look on the Hack Green SDR confirmed 3.5 MHz was very busy, and we soon
realised it was hard to find a run frequency. We also noticed a large
amount of rasping electrical noise on 3.5 MHz, and so decided to
investigate further. At times the signal meter was reading S9 or s9+10dB
and so hearing weaker signals was proving impossible.

We changed the mains supply over from fixed to generator, and the noise
floor dropped by 3 to 5 S points, interestingly it would seem the noise was
coming from the mains, and so this would require some further investigation
and most likely a mains filter project for Chris G8OCV.



The generator proved to be a little problematic, for some reason it was
running a little lean, and so the engine was sounding rather more stressed
than usual. This caused the generator to brown out a few times as it
coughed, wheezed and spluttered in its attempt to generate circa 2KW at
240v. Â*As they often say if something could go wrong, then it most probably
would while your out in the field.

Hopefully the generator will be a simple fix, probably just needing a clean
to the carburetor and no doubt another job to be added to the to do list
before our next event.



While we had some fun, drank some tea and generally worked a few people I
think its safe to say our score wont be breaking any records. As always we
learnt a bit, had fun and generally tried to stay warm.