[TowerTalk] zapped with my dipole. OUCH!

[Grant Saviers]

Good question.

I should have said "carbon comp" instead of "non-inductive".   Carbon 
film and metal film resistors will degrade/fail with high surge 
currents.  Carbon composition resistors have a higher pulse current 
capacity.

An inductive resistor might have an undesired Z at a frequency of 
interest, certainly possible with wire wounds.  If you can characterize 
the Z vs frequency, and it doesn't impact the transmission line, then it 
might be ok.  Since wire wound resistors are available only to a few 
hundred K ohms, this may be academic.

All resistors have voltage ratings, so that is another factor in 
selection.  Perhaps another Tower-Talkian can weigh in on that issue re 
carbon comps.

The value of the resistor should be within its wattage rating for the 
maximum transmitted voltage on the feedline, including whatever 
allowance for SWR.  Obviously, a lower value will have a lower voltage 
drop for a given static charge current level.

Grant KZ1W

On 5/16/2011 11:03 AM, Rex Lint wrote:
> Why would you want a NON-INDUCTIVE resistor?  I'd think inductive would be
> better?
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Grant Saviers
> Sent: Saturday, May 14, 2011 8:53 PM
> To: K2VI;<towertalk at contesting.com>
> Subject: Re: [TowerTalk] zapped with my dipole. OUCH!
>
> My I.C.E. coax arrestors measure 680k to ground on the radio side. It
> seems like a good strategy to bleed off static with a high value
> non-inductive resistor.   10x that amount (6.8Meg) would handle 2500
> volts rms in a 2 watt carbon composition rated for the voltage.
>
> The antenna side I.C.E. has an toroid inductor to ground, value unkown.
> In a rare stroke of good luck the unit I measured was open circuit to
> ground on the antenna side.  Inspection showed the center pin of the N
> connector hadn't been soldered.  Now I have to take all of them apart :-( .
>
> Grant  KZ1W
>
> On 5/14/2011 3:59 PM, Jim Lux wrote:
>> A 1meg resistor to ground?
>>
>> On May 14, 2011, at 13:29, "K2VI"<k2vi at cox.net>   wrote:
>>
>>> It seems every time there's distant lightning and i go to disconnect the
> dipole i get this nasty discharge when i touch the pl-259. Im concerned it
> will eventually damage my tuner and or radio. The antenna is not dc grounded
> like my beam or vertical are. It is a ladder line fed antenna terminating
> into a 4:1 balun outside the shack and a 3' run of rg8 coax to the tuner.
> How can i bleed this static off? I heard from a ham friend the jump a 2.5 MH
> RF choke between the two terminals of the 4:1 balun where the ladder line
> connects.Any advice would be greatly apreciated.73
>>> tony k2vi
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