Posted by
Jim Brown-10 on
Apr 20, 2010; 12:49am
URL: http://elecraft.85.s1.nabble.com/Grounding-negative-side-of-power-supply-tp4424150p4928799.html
On Mon, 19 Apr 2010 19:36:29 -0500, Bob McGraw - K4TAX wrote:
>Now, with the radio connected between the receiving
>antenna and the AC mains, the path for the current difference is through the
>radio and power supply.
I'm with Tom on this one. Here's why. First, remember that lightning is NOT
DC, it is RF, with spectra VERY broadly centered around 1 MH. Second, the
coax from the antenna MUST be bonded to the building entry panel, and from
there to all the house grounds. Third, the coax from the RX antenna SHOULD
have at least one big honker ferrite choke on it at the antenna end, and
another near the station. In other words, there should be at least several K
ohms in series with the coax at the frequency of lightning. That causes
lightning to seek a lower impedance path to earth than one through the house
(and the shack). Like the ground rod at the antenna.
Bottom line -- I don't see a bond helping lightning safety, and as Tom has
noted, it sure doesn't help with RX noise.
73,
Jim K9YC
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