[RFI] DigiKeyer II
EDWARDS, EDDIE J
eedwards at oppd.com
Thu Dec 19 16:39:38 EST 2013
I second the motion to absolutely avoid braid outdoors for any RF site for many reasons including external rectification issues from corrosion. We even avoid it indoors at our work comm sites. Commercial radio sites that must meet vendors' standards like NFPA or Motorola's R-56 guidelines recommend either insulated-stranded or tinned-bare-solid wire for outdoors. And technically better than that is to use solid copper strap; however, this has become a magnet for copper thieves in recent years.
As far as Jim, K9YC's bonding suggestions, it is probably acceptable to do this daisy chaining on anything that's not connected to any RF equipment like computers. But for anything connected to RF equipment, daisy chaining violates the "guidelines" and specs for single-point grounding systems. This may be acceptable as long as the overall shack has proper lightning protection in all other cases.
Jim, K9YC has an interesting presentation on this topic at: http://audiosystemsgroup.com/HamInterfacing.pdf
73, de ed -K0iL
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Dale
Sent: Thursday, December 19, 2013 2:43 PM
To: Peter Laws; jim at audiosystemsgroup.com
Cc: rfi at contesting.com
Subject: Re: [RFI] DigiKeyer II
You mention use of braid to the ground rod outside. That's OK if the braid is encased within some sort of weather-proof cover, such as shrink tubing. The problem with braid that is exposed to the elements is that it corrodes, and unless you inspect it frequently (at least once per year), you could end with no connection (or a very high resistance one). If you do not have covered braid available, replace that run of braid with insulated stranded (the kind used for electrical work - not welding cable) copper wire. No. 6 or No. 4 AWG will be fine.
I've been following the thread. Lots of good input from K9YC, and please do let us know what you find when you reduce power.
>From: Peter Laws <plaws at plaws.net>
>Sent: Dec 19, 2013 1:08 PM
>To: jim at audiosystemsgroup.com
>Cc: "rfi at contesting.com" <rfi at contesting.com>
>Subject: Re: [RFI] DigiKeyer II
>On Thu, Dec 19, 2013 at 10:34 AM, Jim Brown <jim at audiosystemsgroup.com> wrote:
>> Go back and CAREFULLY read what I wrote about bonding everything together by
>> SHORT, FAT COPPER. That means a foot or two of #12 run DIRECTLY from the
>> computer to the radio, another from the computer to the DigiKeyer, another
>> from the DigiKeyer to the radio.
>Done. It's braid from each component (PC, PS, DK, radio) to the
>copper bus bar on the back of the shelf and braid to the rod outside.
>Peter Laws | N5UWY | plaws plaws net | Travel by Train!
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