Tuesday 31 August 2021

Back on air - sort of.

After about three weeks of not having a radio at home, I've now got a passable station up and running from the new QTH!

I had not at all expected to be able to run radio here, partly due to space constraints, and partly due to the expectation of high noise levels, especially due to ADSL internet provision.

An experiment with a magnetic loop, and then a mobile whip system, showed the noise levels were actually quite low.  I decided to string-up a thin wire last evening, into the biggest, shallow-sloping delta loop I could manage.   It's roughly about a 40m loop according to length.

A rush-job in the garage, to test the new sloping loop antenna.
 

As usual, I fed it with 300-Ohm twin, which I reused from a line that had been out in the weather for about 10 years.  For reasons that evade me for the moment, one side of the line was moderately oxidised, whereas the other side was almost as clean as new.  Because the line was connected to a 6:1 balun, which presents a short-circuit at DC, the oxidation of one line can't have been due to an electrical effect - even though it very much looks like one.

Anyhow, I cleaned the contact wire with some steel wool, and made the connections, this time via a 4:1 balun.  Success!  Internal 'tuner' gave all bands down to 60m, and the external match box also produces good matches - just about reaching 80m with some careful tweaking.  Adding a disconnectable wire to the loop will probably make 80m matching easier.

Noise levels with the loop are now very low - no bar indication on the meter at all, and it sounds pretty clean as well.  Conditions were terrible past day or so, but the performance of the loop is pretty much as can be expected for a low sloping loop - could be better, but it will do. 



1 comment:

PE4BAS, Bas said...

Glad you're back on-air John. There is always a way to deploy a station. And the back to basics gives an extra dimension to it all. 73, Bas