Sunday, August 22, 2010

Some antenna grounding work carried out today

Yesterday evening while sitting in the shack I suddenly noticed a beautiful red sky outside. So what did I do? What any sensible ham would do - I grabbed my camera to get a pic of one of the antennas against such a beautiful backdrop.

The photo won't really show it too well, but this antenna is something like 25 years old. It once belonged to a GI ham who is now, sadly, silent key. It lay around at the Dundalk Club (EI7DAR) for a number of years before it was rescued to be brought to my shack. I can tell you it has done a fine job for me, and I've worked some fantastic DX on it.

The antenna is located about 10-12 feet from the shack window here - as I said before it's a smallish property so I am very limited. But I am happy to put RF through this old beast. It has done me some fine service. I recently took it down and shined it up a bit - it was black and is now a dull silvery colour. I also tightened up some of the joints.

I spent some time properly grounding my longwire antenna today. I've been having some "RF in the shack issues" with it. I have a magnetic balun on the feed end, but the problem is the balun doesn't have a ground lug on it. It is claimed it does not need to be grounded.

However, on advice from other hams on a forum, I took steps to put a clamp on the outer of the PL-259 today and ran a very short ground wire to a copper pipe buried about three and a half feet into the ground beneath. So hopefully that will improve things a bit. The photo shows the balun with the longwire coming out from the right, and the clamp all taped up on the left. In the background (the black object) is the top of the copper pipe to which I attached the ground wire using a good jubilee clip and then taped everything up with about half a mile of insulation tape just to keep the copious Irish rain out!

I have read that other amateurs who own the magnetic balun (believed to be a 9:1 unun) are very happy with it. However, reports of serious RF in the shack issues would appear to be substantiated. The manufacturer claims no ground is needed but this goes against all theory! I certainly can say that I have had RF in the shack, but on the other hand I can also say that this antenna has worked very well for me. When I came back in from finishing the job I worked Indonesia (YB4IR) on 17 metres CW!! So it's obviously working well!

I also put in a better ground system for the station here today too. That involved a four and a half foot length of copper into the ground just outside the shack, about two feet from the window. Again, that should improve things a bit.

5 comments:

  1. Hello Anthony, great photo nice sky. The antenna is difficult to see but anyway I believe it's shining hi ;-) RF problems in your shack can be a little tricky. How did you connect your ground "rod". As it is important you do connect it with a thick short as possible cable. At my previous QTH I connected a 33 ft ground rod with the base of my antennamast and with the antennatuner using welding cable. Almost no RF problems then anymore. 73, Bas

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  2. Bas, the cable running from the crocodile clip is a fairly thick cable of stranded copper, but is just too short to reach the ground pipe, so I used two short lengths of thick earth wire to bring it the rest of the way. The earth wire is secured to the copper pipe very tightly with a jubilee clip and all taped up.

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  3. Good morning Anthony, Very nice picture of the sunset, even better with the vert in the forefront. As for RF in the shack mine is making it's way into my wife's IMac. Will be investigating and blogging that soon.
    Best wishes from Canada

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  4. VE3WDM, Thanks for the nice comment. One of the unnerving symptoms of RF in the shack here is a series of errors which appear on my laptop here in the station. I get errors on LOGic8, I get other bings and noises which is obviously Windows telling me it doesn't like something. And also I have a wireless keyboard which stops working half the time. It's not so bad since I installed the grounding for the wire, but it's still there to an extent.

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