[Elecraft] Grounding question on remote tuner

[Ron D'Eau Claire]

While I've pulled Fred's stunt at times in the past, be aware that having two grounds can be very dangerous. If something opened the circuit to the mains ground at the house, you could find mains voltage (120 or 240 Vac) between the coax connector from the shack and the tuner at the antenna when you disconnect it for any reason. 

The smart move is to run a heavy copper wire alongside the coax from a ground point in the house to the ground at the antenna so that both are grounded together. 

I agree with Barry about the unun. I'd not use it (and don't on my Inverted L, but I am not using an MFJ tuner either). If you have a decent "RF ground" at the tuner you probably will not need any further isolation.

73, Ron AC7AC 

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Fred Jensen
Sent: Wednesday, April 5, 2017 12:31 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Grounding question on remote tuner

Assuming I understand your configuration and that when you say "isn’t the tuner already connected to the ‘system ground’ via the coax shield?" 
you mean the 3 ft of coax from the 4:1 transformer to the tuner:

The 3 ft path from the transformer ["unun"] to the tuner is handled by the coax.  The "tuner ground" would then become a safety ground ... 
which is a very large, long, and tedious subject involving the NEC, UFER's, large conductors, a lot of work, and possibly $$.

If "long coax to the shack" means the tuner is a long way from the shack and your service entrance, I'd drive a ground rod at the tuner and connect the lug to that.  I'm probably wrong, but that's what I'd do.

73,

Fred ("Skip") K6DGW
Sparks NV USA
Washoe County DM09dn

On 4/5/2017 11:19 AM, Randy Cook wrote:
> Weather damage repair time. I am rewiring my ~84 foot inverted L antenna system, Up a SpiderPole about 31 feet, out about 53 additional feet. Still tuning length.
> I have mounted a remote MFJ tuner on a post about 3 feet from the antenna base. Antenna wire goes down the pole, connects to 4:1 Unun input lug, then goes via coax to tuner. Out of the tuner to a long coax run to my shack. Choke at the rig end of the coax run.
> Radials mount on ground connection lug on the Unun.
> I was a bit confused with the tuner wiring. The manual says to connect ground lug to the ‘system ground’, I assume that means the radial collection point. But, isn’t the tuner already connected to the ‘system ground’ via the coax shield? Is it necessary to run another wire from the tuner ground to the radial connection ground?
>
> Thanks in advance for any advice.
>
> 73
> Randy - K6CRC
>

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