Friday, 13 February 2015

RF in the shack!

my previous PC picked up a little interference when I was using CW on 10m with my G5RV 1/2 size.

just a slight ripple on the monitor.

well, new PC and new monitor and the whole thing freezes when I use 10m.  then takes 5 seconds or so to come back to life afterwards.

not good!!

so I asked those wise people over at Hamradiodeals what to do about it.

Naturally, as this was Hams there were a whole range of ideas!!

as always the old chestnut of "ditch the coax and go twin feeder came up, and while I accept that it may well work, I have three antennae, all connected by coax, and I have no experience of twin feeder other than as a part of a G5RV, so I'll respectfully pass on that.

other ideas were ferrite sleeves at the antenna end, a 1:1 balun and an ugly balun.

my ebay empire has been passable recently so I jumped on and ordered the bits to do all the above.

except the twin feeder thing!

first to arrive was the FT240-43  ferrite toroid (£7.99 inc post).  Google provided me with this diagram from VK6YSF

Figure 2  Wiring of the 1:1 Ruthroff voltage balun. 

OK, seems straight forward enough......

a rummage in my scraps box produces the wire, a plug and a socket......

as many turns as would fit on the ring.....

a few solder joints....

and a quick test before I bother to find a case.....

now, as some point I WILL case it up nicely.... but right now, the RF in the shack is gone, and on a pretty much dead 10m band I had a 10m QSO with UY5BO in Ukraine within seconds, and a couple of 20m contacts to make sure all was well there too.

so, problem solved for a total cost of £7.99, a few scraps and about 1/2 an hour's tinkering.