[TowerTalk] Rain drops noise on Yagi (dipole)

[Grant Saviers]

W8JI on his website makes a good case that "p-static" is really St. 
Elmos fire - i.e. corona discharge.  We had the same noise problem 
(S9+20) with the 80m beam top antenna in a snowstorm and listened 
instead on the 4sq receive antenna which was noise free. Other yagis on 
the same tower were quiet.  That experience reinforced my opinion that 
W8JI is correct.

https://www.w8ji.com/beverages.htm  scroll down to "Types of Beverage Wire"

So having an antenna or other dissipative structure above the top 
antenna might help to get corona current off the top antenna, but there 
is a lot of bad folklore about such widgets.

Avoiding sharp points, square tube ends, etc are ways that corona is 
managed in high voltage systems, so these might be ideas to consider.

Grant KZ1W


On 12/2/2018 14:44 PM, Guido Tedeschi wrote:
> On our contest station we have an old but good KLM 3 element linear 
> loaded Yagi for 40m, 20m high, which works fine except for the high rain 
> drops noise on RX.
> 
> Normally we have an average noise floor of S1, but during last CQWW SSB 
> and CW contest, we suffered rain during nights and the noise on 40m 
> raised even to S7-8 when the rain was strong.
> 
> Is there anything I can do, to avoid or greatly attenuate that noise?
> 
> There is a coil across the dipole feed (sometimes called Hairpin), to 
> match the impedance to 50 ohm, followed by a current balun/choke; what 
> if I connect the center of the coil to the boom/ground, could this help?
> 
> Thanks and 73
> 
> Guido, ik2bcp
> 
> 
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