[TowerTalk] Rain static

[K4SAV]

Some mobile antennas have a loading coil at the base that DC grounds the 
antenna and provides a leakage path, other do not.  All the radios I 
have seen do not provide a leakage path for charge on the antenna 
terminal.  They are capacitively coupled. So it is possible to build up 
a charge on the antenna that is enough to break down this capacitor if 
there is no leakage path.  This has never happened on my mobile even 
with close lightning strikes.  That doesn't mean it isn't possible. If 
it makes you feel better, you can always add a surge suppressor - it 
doesn't hurt.  You can ohmmeter your system to see if you have a leakage 
path or not.

If you are attaching your mobile rig to a large external antenna, then 
you need some protection.  Long antennas such as 80 or 160 meters, can 
gather significant energy and need some kind of gas discharge protection 
device, or other discharge devices such as an inductor, to drain off 
static charges as well as good grounding for lightning. The gas 
discharge device would be preferable, since the inductor may not get 
spikes introduced by close lightning strikes. If you have this connected 
to your mobile rig, I would recommend disconnecting it when bad weather 
is near, and attaching the feedline to a good ground.

I can't speak for aircraft antennas, but I would expect they would need 
very good protection also.

Jerry, K4SAV

doc wrote:

>It is just that I am reading that even mobile the static energy
>is capable of building up to the point that it is capable of
>harming the front end of a rig.  Considering the cost of a modern
>rig for HF or VHF/UHF may it not become a "better safe than sorry"
>equation or will such devices not really function properly in a
>vehicle?
>
>I also wonder about mobile/portable where the rig is in the
>parked vehicle but the antenna is a dipole, V, or other
>external ground-pole mounted antenna cabled back to the
>vehicle.
>
>
>K4SAV wrote:
>  
>
>>  You definitely need surge protection on your home antennas, not 
>>necessarily for precipitation static, but for lightning strikes. It is 
>>probably an overkill for mobile antennas.  I base that conclusion from 
>>having spent many years operating in central Florida, which included 
>>several close lightning strikes, and I have never suffered any damage to 
>>my mobile gear.  Although, I suspect with a direct hit everything would 
>>be toast.
>>
>>Jerry
>>
>>doc wrote:
>>
>>
>>    
>>
>>>Given this discussion I have a question of application, if I may?
>>>
>>>Does the presence of this static, often capable of gathering to
>>>a significant potential, suggest that we need surge protection
>>>on both base and mobile gear?
>>>      
>>>
>
>  
>