Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: grounding question  (Read 1902 times)
KF7ZFC
Member

Posts: 121




Ignore
« on: October 31, 2017, 11:18:36 AM »

I am going to install an 8 foot copper grounding rod in AZ soil.

A coax lightining suppressor made by Industrial Communication Engineers will be installed on the rod

My question is this will this the right way to do this?

The the series of components will be:

a 4 way antenna switch activated via dc on the coax

on one port of the switch will be an endfed antenna mounted in the eaves of house

the second port will have 3 seven foot Hamsticks (40, 20 and 17m) connected together thru a passive connection

on the third port eventually will be MFJ 1786 or 1788 Mag Loop
Logged
W9IQ
Member

Posts: 1706




Ignore
« Reply #1 on: October 31, 2017, 12:08:38 PM »

Quote
A coax lightining suppressor made by Industrial Communication Engineers will be installed on the rod

My question is this will this the right way to do this?

The the series of components will be:

a 4 way antenna switch activated via dc on the coax

Take care as many lightning suppression devices contain a capacitor in series with the center conductor. This will block any DC from reaching your remote antenna switch. The 300 series of ICE devices have this series capacitor and also have an inductor between the center conductor and the ground. This will act as a short circuit to any DC signals on the "antenna" side of the device. There is also a resistor on the "radio" side of the device that would dissipate power from the DC control voltage.

For example, from the ICE 300 series of lightning suppression devices web site:

Quote
All 300 Series units feature heavy discharge toroidal inductors used to neutralize developed voltages on the antenna side of a central high-voltage blocking capacitor.

Here is a schematic of the ICE 300 series to show you the problem. The 300 series is the schematic on the right.



Polyphaser does manufacturer a version of their lightning suppression device that does not include the series capacitor. This would be more suited for your 12 volt control circuit albeit with a lower level of protection from static discharge.

- Glenn W9IQ
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
KF7ZFC
Member

Posts: 121




Ignore
« Reply #2 on: October 31, 2017, 01:12:22 PM »

Thanks Glenn
Logged
K4SAV
Member

Posts: 2387




Ignore
« Reply #3 on: October 31, 2017, 01:52:39 PM »

The manuals for the MFJ-1786 and MFJ-1788 both say that the control voltages for the antenna are fed down the coax line.  Since the control voltages for your 4 way switch are also fed down the same coax line, this isn't going to work.

Jerry, K4SAV
Logged
KF7ZFC
Member

Posts: 121




Ignore
« Reply #4 on: October 31, 2017, 02:24:58 PM »

Jerry

Ouch.

The present coax line was installed inside a wall, up to the attic, and  across the attic before the house was finished. After construction we then drilled a hole in the eave and pulled out the coax.

With the current coax cable, I could do manual switch outside the house with another suppressor to feed the MFJ loop.

It would be a short walk from my operating position from inside the house. Living in sunny and warm Arizona it would not be a problem

Is there another solution?
Logged
WB6BYU
Member

Posts: 17064




Ignore
« Reply #5 on: October 31, 2017, 02:41:27 PM »

Run a separate control wire to the antennas / switches that need them.
You can use the coax shield for the ground return.  It doesn't have to
follow the same route as the coax.

And you probably only need one separate wire to the switch:  it can connect
to the common connection there and get switched to whichever antenna
needs it.  (You'd need to organize your shack wiring carefully if you had
two different antennas that needed remote D.C. for tuning.) Or jet it to
power the switch and bypass the internal capacitor to let he remote
tuning voltage pass through.  Make sure you can handle the case of a
loop antenna or other type that looks like a short circuit for D.C.
Logged
W9IQ
Member

Posts: 1706




Ignore
« Reply #6 on: October 31, 2017, 04:12:20 PM »

Quote
Run a separate control wire to the antennas / switches that need them.You can use the coax shield for the ground return.

That is a bad plan as it essentially bypasses the lightning protection circuit. Any large EMF will pass from the antenna connection in the switch, to the switch control logic, and into the shack. Poof!

- Glenn W9IQ
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
KF7ZFC
Member

Posts: 121




Ignore
« Reply #7 on: October 31, 2017, 04:58:16 PM »

I was thinking

3 Hamsticks on position 1 of remote switch and endfed antenna on position 2 of remote switch followed by suppressor then to position 1 on manual switch to transceiver

MFJ Loop followed by another suppressor then to position 2 on the manual switch
Logged
K5LXP
Member

Posts: 5300


WWW

Ignore
« Reply #8 on: November 01, 2017, 06:47:04 PM »

No mention of a connection to the service ground, which should be part of a surge ground system.

Personally, I don't see anything here that merits a lightning ground.  I wouldn't bother for such a minimal installation, but that's just me.

Mark K5LXP
Albuquerque, NM
Logged
KF7ZFC
Member

Posts: 121




Ignore
« Reply #9 on: November 02, 2017, 06:04:46 AM »

Mark

To reach the service ground would require at least a 100 foot connection

Steve
KF7ZFC
Logged
K5LXP
Member

Posts: 5300


WWW

Ignore
« Reply #10 on: November 02, 2017, 12:21:26 PM »

"By the book" it's required.  Without it, at best you create an opportunity for a ground loop, at worst a lethal shock hazard.  Not sure what your goal is, if it's to be "safe" or you read somewhere you need to do this.  But like a lot of things to do it only part way can be worse than not doing it at all.  What is the problem you're trying to solve, then do the thing that actually solves it.  I wouldn't consider some mobile antennas and a wire on the eaves to be a significant lightning risk, especially when compared to the utilities that come into your home comprised of miles of conductors you're directly connecting equipment to. 

Mark K5LXP
Albuquerque, NM
Logged
KF7ZFC
Member

Posts: 121




Ignore
« Reply #11 on: November 02, 2017, 02:33:40 PM »

Mark

Thanks for your comments.

The electric utilities lines are below ground.

Back in December I asked Joel Hallas W1ZR, contributing editor for QST about my problem. He gave me information that covers what you said. All equipment including computer, monitor and ham equipment will have a single point "ground" connection.

Some of the things I can do but the most difficult is running a buried heavy wire to the power utility ground. There is a paver pathway to the house and then a 2 car plus wide parking area also with pavers.

I am not sure I can do much more
Logged
WB4SPT
Member

Posts: 483




Ignore
« Reply #12 on: November 04, 2017, 07:19:51 AM »

You can water blast a 1/2” pvc conduit under a 2 car driveway.  If what u have is sand.
Logged
KB2WIG
Member

Posts: 358




Ignore
« Reply #13 on: November 04, 2017, 08:23:56 AM »



Can't you lift the pavers and run your cable?

KLC
Logged
K5LXP
Member

Posts: 5300


WWW

Ignore
« Reply #14 on: November 04, 2017, 10:27:48 AM »

Back to my last post, what problem are you trying to solve?  The antennas you're proposing don't substantially increase the probability you'll be struck, so is this an issue you're trying to address just from the utility standpoint?  BTW, utilities underground don't change anything as far as surges.   A utility can be struck some distance away and the surge can still be destructive.  So as you've observed it's a "whole house" solution and if you're willing to do that then fine.  If your residence has had a perpensity to be struck and that's the problem you're solving then that's the road to go down.  If the concern is that putting a small ham radio antenna on your house somehow makes you a big target, then it's my opinion that you're going to spend a lot of money and effort for a problem that doesn't exist.   The corollary of that is if you're going to put in a lightning ground and do it right, put in a commensurately large antenna system that makes all that effort worth it.

Mark K5LXP
Albuquerque, NM
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!