[Elecraft] Nearby Ham Interference

[Dave Olean]

Hello Brendan,
I have two ten meter 5 el yagi antenna arrays that are just under 300 ft 
apart. One is on a 70 ft tower and consists of three yagis. The other  is a 
single yagi at 30 ft. If the two yagis are boresighted on each other, I see 
only 17 dB of attenuation between them. I checked the isolation with a 
signal generator and a crystal detector with an HP 415E meter. This can blow 
out a front end even running 100 watts. Each yagi has almost 9 dBd gain in 
free space.  I guess it depends on what ur antenna is, but yagis on the 
higher bands can cause problems when aimed at each other. I did fry one K3 
using an amp with this setup. I took out a diode.
Be careful, and make a few checks to avoid surprises.
Dave K1WHS
----- Original Message ----- 
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: <elecraft at mailman.qth.net>
Sent: Wednesday, January 20, 2016 12:30 AM
Subject: Re: [Elecraft] Nearby Ham Interference


> On Tue,1/19/2016 3:05 PM, Ian wrote:
>> Consider one of these:http://www.dxengineering.com/parts/dxe-rg5000hd
>
> The K3 is pretty well protected -- if, for example, you hit it with too 
> much signal, the attenuator will kick in and the preamp will turn off. And 
> if that doesn't reduce the signal enough, you'll get a HIGH SIGNAL warning 
> on your display. In addition to that, there's a diode on the front end.
>
> I'd verify that an RX is getting overloaded before spending dollars on 
> this product. With antennas 300 ft apart, it's unlikely that you're going 
> blow anything up unless the other station is running an amp.
>
> 73, Jim K9YC
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