[TowerTalk] Corona Electromagnetic Interference

[K8RI on TT]

On 4/24/2011 11:58 PM, Kipton Moravec wrote:
> On Sun, 2011-04-24 at 19:42 -0500, Barry Merrill, W5GN wrote:
>> I'm really confused.   This is an FM repeater, so the noise is capturing the
>> receiver,
>> turning on the repeater, and you hear all the noise, only when it's raining?
> No. The nois is bad when someone wants to use the repeater. Mobile
> stations as so noisy they are hard to understand. One of the NCS usually
> has full quieting at 25W had to go to 75W to be understood.
>
> When there are not storms nearby everything is fine, and we get 50-60
> mile range to mobile stations. It goes away quickly when the storms
> pass.  The storm may or may not have rain at the repeater.
>
> We do not think it is a moisture problem because it clears up before
> things have a chance to dry up.
>
>
>> Or, the noise never captures the receiver you only hear noise when a station
>> has
>> captured the rf and turned on the repeater and then you hear lots of noise?
> Yes.
>
>> I know from submerged operations from Navy Submarines that if this were 10
>> meters
>> SSB or CW, it sounds like rain static and you only need a high ohm resistor
>> from the antenna to ground.
>>
>> Barry, W5GN
> That is what I am wondering about. Using a 1M to 10M resistor from the
> center conductor to the ground, to bleed off any static. That high of a
> resistance would not affect operation.
>
> Kip
>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com
>> [mailto:towertalk-bounces at contesting.com] On Behalf Of Kipton Moravec
>> Sent: Sunday, April 24, 2011 6:27 PM
>> To: Fuqua, Bill L
>> Cc: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Corona Electromagnetic Interference
>>
>> On Sun, 2011-04-24 at 01:59 -0400, Fuqua, Bill L wrote:
>>> If you have not had a problem in 4 years and now you do you may look into
>> other electrical hardware on the tower.
>>> It may me lighting systems that have started to arc when there is
>>> heavy rain or some other electrical problems caused by rain or wind.
>>> If it is particularly cold it could be ice on the antenna which detunes
>> it. Water has a very high dielectric constant.
>>> Unlikely corona.
>>>
>>> 73
>>> bill wa4lav
>>>
>> When we inspected the system yesterday, we noticed none of the antennas were
>> properly grounded to the tower where they clamped onto the upright of the
>> railing around the top of the tower.

I was wondering if this might be desense.
If you are losing grounds this would change the impedance and how well 
the cans were working.


73

Roger (K8RI)