[TowerTalk] [RFI] Back of desk grounding buss

[Roger (K8RI) on TT]

On 3/20/2014 5:37 PM, Mike Fahmie wrote:
> I had originally
Copper, or Aluminum 1/8th to 1/4" thick, drilled, counter sunk (on the 
back) and tapped for 10-32, or 24. Insert brass, flat head screws (from 
the back).  Use brass wing nuts and brass washers that let me use ring 
terminals. (I always use ring terminals on safety grounds) If Aluminum, 
use Noalox on brass screws where they thread into the Aluminum and 
between the first brass washer and Aluminum. Used in this fashion, the 
threads are not a problem in either metal as the screws are inserted and 
left there.

I prefer a 2" wide by 1/4" Al, or 1/8th inch X 1" (minimum Cu.)
Using the screws you don't have the problem of holding wires, washers, 
screws and nuts. First washer is stuck in place, ring terminals of the 
right size tend to stay put. Second washer usually stays put on 3/4 to 
1" long screws.  So the only juggling is getting the wing nut on.  This 
is very much like the grounding connection on most rigs.  You can solder 
the screw heads in Cu, but don't over heat the copper or screw and use a 
minimum amount of solder.  It's not necessary, but will insure the 
screws never come loose.

I haven't done it yet at this QTH (only been here 30 years) but hope to 
get a "round toit" one of these days.  At present, I use the shield of 
8X to ring terminals on each end, they are roughly the same length and 
go to a common point on an extension of the #2 copper from the common 
point ground just out side.

73

Roger (K8RI)

>   replied to KG2V's query offlist, but after reading other replies I decided to post my reply to the entire list to share my concerns about using Aluminum in this application.
> -----------
> Since I've been bit as the result of an insulating oxide layer on an
> Aluminum connection, I wouldn't recommend it for your ground buss.  I
> use copper, but since it is relatively soft, I don't count on tapped
> threads, I use a nut on the backside.  If it's heavy enough so that it
> is mechanically robust, then it's probably sufficient electrically.
>
> -Mike-
>
>
>
>
>> ________________________________
>> From: "n0tt1 at juno.com" <n0tt1 at juno.com>
>> To: Charlie at TheGallos.com; rfi at contesting.com; TowerTalk at contesting.com
>> Sent: Thursday, March 20, 2014 1:51 PM
>> Subject: Re: [TowerTalk] [RFI] Back of desk grounding buss
>>
>>
>> FWIW, I just use a 1/8" thick x 3/4" wide aluminum bar
>> stock from the hardware store.  Goes along the back
>> of the desk (near the top) and is periodly tapped for 8/32 screws
>> to accept AL/CU rated "spade" lugs that connect to the
>> various equipment "boxes" with ~1/4" braid.  Then the strip is
>> connected to the station ground.  Works for me.
>>
>> 73,
>> Charlie, N0TT
>>
>> On Thu, 20 Mar 2014 13:53:19 -0400 Charlie Gallo <Charlie at TheGallos.com>
>> writes:
>>> Hey Gang,
>>> Sort of antenna, sort of RFI, more safety..
>>>
>>> I've decided my back of desk grounding situation needs to be
>>> improved
>>>
>>> Now, we all know the standard is a nice, thick copper buss.
>>> Question is, how thick? - this will then be run down to the
>>> panel/ground rod
>>>
>>> Is Brass/Aluminum/Copper PIPE a valid alternative?  If aluminium,
>>> again, how large (I normally have round up to about 3" diameter
>>> sitting in the shop, as well an AL plate (various sizes, 3/16 thick
>>> up to 6" wide is everyday, and I have angle up to 5" wide legs, 1/4"
>>> thick around, and blocks up to 2" thick and 4" wide hanging around
>>>
>>> I intend to silver braze most of my connections, but obviously that
>>> won't work to an Al  plate,  That I'd drill, tap, and either use
>>> studs with nuts, or screws
>>>
>>> Again, we aren't talking the wall pass through here, but the buss at
>>> the back of the desk
>>>
>>> -- 
>>> 73 de KG2V - Charles Gallo
>>> Quality Custom Machine-shop work for the radio amateur (sm)
>>>
>>> _______________________________________________
>>> RFI mailing list
>>> RFI at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>
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