Topband: Tuesday evening DX ( was "Excessive noise on beverages")

[David Olean]

Luke,

I was really happy with this past evening/morning's events.  I was 
listening around  1825.5 and immediately heard you calling CQ when you 
first started up. When W6IZT did not answer you, I figured I would give 
you a call from here in Maine.  I had been previously calling CQ up the 
band and the RBN skimmers in ZL as well as VK had found me so I knew the 
path was open.  What surprised me was the direction that I heard you. 
You came in best on my beverage wire aimed at 220 degrees, southwest.  A 
few days ago, this same wire was useless as it had very high noise 
levels during the evening hitting about -105 to-100 dBm as measured on 
my K3 P3 combination.  When I worked you, the noise level was running at 
about -132 dBm. The crazy thing is that I also heard DU7ET very well on 
the southwest wire. I had already worked Robert in the past so did not 
call. Normally he would peak northwest or maybe even 330 degrees, but 
today it was southwest also! If the beverage had not been worked over 
these last few days, then I never would have heard either of you folks!  
DU7ET peaked up at 559 at my sunrise with a great signal for a short 
time.  You peaked even louder!

I just finished modifying the 220 and 270 degree beverages a few hours 
earlier. I had originally installed them with everything done wrong.  
Listening to comments on this reflector and buying the latest version of 
ON4UN's Low Band DXing book provided me with all I needed to know and do:

1. Relocate the transformer end of the beverages farther away from the 
TX vertical to reduce coupling. 50 ft vs 150 ft. I did not initially 
have the 50 dB of isolation required between antennas at the closer 
spacing.  (+10 dB)

2. Do not use a single ground rod for two beverages at the same place.  
(?  did not measure)

3. Have a good broadcast band reject filter in the rx line to protect 
the radio from strong signals.  (5 dB or more)

4. Add common mode 1:1 chokes in the feedline. These lines were rather 
short at just over 100 ft. I added a second ground rod 20 ft from the 
transformer end and installed a homebrew 1:1 balun as per Low Band 
DXing.  I did the same thing where the coax enters the building. I 
banged another ground rod in the frozen ground there and cut the coax to 
place a second 1:1 choke balun right there at the entry point.  (+ 5-10 dB)

The net effect was an improvement of around 27-30 dB after all the 
changes. I can finally hear to my west! In some cases I could attach an 
improvement ratio in decibels to each improvement. They all added  up.

Thanks to all who provided info on what improvements were needed. It was 
fun doing all the work in deep snow and frozen ground too. That is what 
hams do. We pick the worst times to do antenna work!

73

Dave K1WHS



On 3/13/2018 2:01 PM, VK3HJ wrote:
> This evening I was pleased to be hearing North America again at last. 
> I worked one here, one there, then a pileup started. About two dozen 
> stations across 14 states was a most enjoyable bounty!
>
> There was even a 100 watt station who worked me for his first VK on TB!
>
> Also heard was DU7ET in the Philippines, a few JAs, and I heard XX9B 
> calling CQ but not working anyone.
>
> I will attempt to rise early and see if the band is open to Europe! My 
> sunrise is 2014z and I find Europe starts to come in best in the 
> twenty minutes after sunrise.
>
> 73,
>
> Luke VK3HJ
> _________________
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>