Thursday, 27 March 2014

Antenna works

I did not go out last weekend due to the weather. So I took the chance to do some work on my antennas.

I built a linked EFHW for 17,30,40/20m using insulators, crocodrile clips and Hi-Viz antenna wire.  I used my G11 SDR QRP to test on 17m, having not used this radio for a while I was quickly reminded how good this SDR is. With the band open, I bagged a few contacts quickly with pretty decent reports. It was easy to tune to visible signals in the pan-adapter, select a 100Hz filter and go for it. The sidetone is a lot smoother than my HB1B. I tested 30m as well with no problem. I hope I can go out with it this coming weekend.
I am thinking of building another one for the higher bands - 15-17-20m.
264gr - 4band efhw antenna

testing 17m

I also had a look to my fixed doublet in the garden. This antenna is a 20m wire (inverted U - 15m horizontal lenght) at 6m height (cloud burner) fed by about 10m ladder line. The ladder line connects to a Gwhip 1:1 current balun and then the MFJ-901B tuner fed by 8m of RG213 coax inside the house. Thanks to Mike M0MTJ who helped me with the design and implementation. www.mds975.co.uk

 I had had problems tuning the antena when changing bands in the previous two weeks and found the culprit - one of the coax jumpers - open ground. I yet have to test a suspect BNC to 4mm socket adaptor. As a temporary solution I am using the balanced feed conection (4:1 voltage balun) in the tuner.

MFJ901b


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