Topband: OT - Bonding Radials at Intersections

[Jeff Blaine]

Wow, that's amazing.

I suppose the risk of micro arcing then specifically with insulated 
radials has got to be closer to zero - at least until the insulation 
breakdown was sufficient to facilitate the arcing. If that's a 
reasonable guess, then maybe guys like me - who are from the start not 
going to cross connect - would have some benefit from the use of 
insulated wire in that it would side step this issue for the most part?

In any event, when I do get around to building my personal MW station - 
needed in anticipation of the zombie apocalypse - for THAT set of 
radials, I will definitely plan on doing the cross connect work!

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 11/7/20 12:39 AM, donovanf at erols.com wrote:
> Hi Jeff,
>
>
> Micro arcing can be excited by just a few volts of RF. While micro arcing
> probably is n't a fire risk, micro arcing radiates low level phase noise
> on transmitted signals. This is can cause a serious interference
> problem to nearby receivers such as neighboring hams or co-located
> receivers such an in-band receiver in a contest station.
>
>
> I personally experienced these problems with megawatt transmitters.
> In one instance, a massive radial system for a one mile long of array of
> HF phased verticals had to be completely replaced because it generated an
> elevated noise floor that degraded the performance of the HF over the
> horizon radar. In another case a poorly engineered, badly installed and
> inadequately maintained radial system for a 500 kw VLF system caused
> severe television interference to neighbors that forced premature site closure.
>
>
> 73
> Frank
> W3LPL
>
> ----- Original Message -----
>
> From: "Jeff Blaine" <KeepWalking188 at ac0c.com>
> To: topband at contesting.com
> Sent: Saturday, November 7, 2020 5:43:25 AM
> Subject: Re: Topband: OT - Bonding Radials at Intersections
>
> I of course defer to Frank's expertise here. But after thinking about
> this for a couple of hours, I'm trying to wrap my head around this arc
> risk concept as well. It's interesting and I toss this comment out
> because my two sets of 4sq don't have a single cross-bonded wire
> anywhere - all the ground structure is ground mounted, with overlapping
> wires literally all over the place. And despite that, the do seem to
> work more or less OK, as far as I can tell.
>
> I guess my thinking is list this... All those radial wires are laying
> out on the ground. So they are at least connected at some point, at a
> DC level, assuming your talking about something conventional like a 4SQ.
>
> Of course, we are talking about AC here, so I will agree that maybe the
> conditions could exist where - with just the right configuration between
> the two radials - that some larger than expected voltage differential
> may be present. Given how low Q a 4SQ is, how current is split between
> multiple elements, my gut feeling is that the excitation voltages are
> pretty mild even if you have your 1500W source right there at the 4SQ
> input.
>
> And on top of that, the wires are laying on the ground, right? The
> radials are in more or less intimate contact with the ground, so I would
> expect there to exist leakage resistance between adjacent conductors (if
> they are bare). And if they are perfectly insulated, this being AC,
> that means there is going to be some amount of cap coupling between
> adjacent wires and to the ground. With all of that R&C spread out all
> over the field, I would certainly think this conspires to work against
> the probability that any two optimally aligned individual crossing
> conductors would provide a condition sufficient to support an arc, and
> that if so, it would survive long enough to cause a fire.
>
> It's very very very dry here in the summer and again in the winter. So
> fire risk is something we keep a real close eye on. Then again, out here
> in the Midwest some of us do a lot of IL-advised things because they
> seem to work and of course because laziness is a BIG part of the
> calculation. ha ha. Maybe we have been taking a walk on the wild side
> without realizing it. Hope not because I sure don't want to go try to
> rectify this poor decision 3 years post installation! Say it ain't so!
>
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
>
>
> On 11/6/20 10:59 PM, donovanf at erols.com wrote:
>> Always beware of any communication that begins "with all due respect"
>>
>> ----- Original Message -----
>>
>> From: "Wes" <wes_n7ws at triconet.org>
>> To: topband at contesting.com
>> Sent: Saturday, November 7, 2020 4:49:23 AM
>> Subject: Re: Topband: OT - Bonding Radials at Intersections
>>
>> With all due respect, I must ask, how many megawatts are you guys running?
>>
>> Wes N7WS
>>
>>
>> On 11/6/2020 3:26 PM, donovanf at erols.com wrote:
>>> Hi Carl,
>>>
>>>
>>> If the insulation breaks down they will arc, potentially causing a fire
>>>
>>>
>>> 73
>>> Frank
>>> W3LPL
>>>
>>> On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote:
>>>> On 11/6/2020 1:10 PM, Carl Clawson wrote:
>>>>> Frank,
>>>>>
>>>>> “Must” is a strong word. What goes wrong if you cross them?
>>>>>
>>>>> 73, Carl WS7L
>>>>>
>>>> Also, if insulated wires are used for radials that cross
>>>> over each other, is that to be treated differently than bare
>>>> metal wires that cross over each other and touch
>>>> so as to have electrical connectivity?
>>>>
>>>> Does it matter if cross over radials are soldered at the
>>>> crossovers, so as to prevent parasitic "diodes".
>>>>
>>>> For whatever weird reason, the price of insulated wire is
>>>> nearly always lower than the equivalent bare wire. And
>>>> Romex sells for less than the equivalent individual wires.
>>>>
>>>> Rick N6RK
>>>> _________________
>>>> Searchable Archives:http://www.contesting.com/_topband - Topband
>>>> Reflector
>> _________________
>> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
>>
>> _________________
>> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector