LF: Re: [Lowfer] Protecting E probe antennas in near field of LF TX antennas

["Jay Rusgrove" <JRusgrove@comcast.net>]

Dave

 

I have several ground mounted 1-meter e probe antennas (Amrad design but with J310, no ferrite bead and NE-2 replaced with a 75 volt gas-filled surge arrestor) located about 75 feet from my 1 watt ERP 137 kHz setup and haven't suffered any failures...this with no external protection. Not suggesting this is a good idea...  just to note that they can be pretty robust.  

 

I did lose a CP666 or two (original device used in the Amrad antenna at about $15 a copy) to lightning but since I switched to the J310 there haven't been any failures. Probably because the J310s are cheap and I have plenty in the junk box ;~)

 

Jay W1VD / WD2XNS

 

----- Original Message -----
From: "Dave Brown" <tractorb@ihug.co.nz>
To: <rsgb_lf_group@blacksheep.org>; "Discussion of the Lowfer (US, European, &amp; UK) and MedFer
bands" <lowfer@mailman.qth.net>
Sent: Wednesday, February 28, 2007 6:51 AM
Subject: [Lowfer] Protecting E probe antennas in near field of LF TX antennas


> Has anyone done anything along the lines of  the subject line using a
> mechanical switch/relay arrangement?
> I expect that any electronic method would add considerably to the
> capacitance from the probe 'antenna' to ground so the best option
> would seem to be to use something like the mechanical arrangement in
> the old Dow-Key coax relays that had the 'isolated' receive side
> contact. This will require a relay of some sort in the E probe that
> operates to remove the protective earth only when on receive.  I'm
> still mulling over the best mechanical arrangement to implement this
> scheme-all ideas most welcome.
> 73
> Dave, ZL3FJ
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