Re: Prevent Snow/Dirt Static damage to KPA100 after upgrade
Posted by
Don Wilhelm-4 on
Oct 24, 2010; 12:25am
URL: http://elecraft.85.s1.nabble.com/Prevent-Snow-Dirt-Static-damage-to-KPA100-after-upgrade-tp5666395p5666665.html
Ken,
If you salvaged RFC10 from the KPA100 upgrade, I suggest you use it.
The only problem is that it cannot live inside the KPA100 because it
couples into the base K2 circuits causing spurious responses and all
kinds of "strange happenings".
You mentioned using a T connector - certainly, just mount the 100 uHy
choke in a PL-259 - one lead to the center conductor and the other to
the shell. Place that PL-259 on one side of the T adapter, and connect
the antenna to the other.
A resistor will do OK, but the choke provides a better low DC resistance
path than a resistor.
73,
Don W3FPR
On 10/23/2010 5:07 PM, Kenneth A. Christiansen wrote:
> 40 years ago we had a windy dust storm in Bismarck ND and I lost the RF
> amplifier in my new solid state Heathkit receiver three times that day
> before I realized the dirt and high winds were putting a static charge
> on my antenna. I found there was a capacitor between the antenna and the
> RF amp and the static would arc across the capacitor and burn out the
> RF amp. Of course tube type receivers did not have this problem. I found
> out a 100K resistor from the antenna to ground would prevent this and
> not load down the antenna.
>
> Several years ago my friend I each bought a new IC-746PRO. The first
> time we had a blizzard with 50 MPH winds and snow my friend and I both
> burned out our new rigs with snow static trying to check into the ND
> Weather Net. The K2 survived just fine. The IC-746PROs were both fixed
> under warranty but it still cost both of us shipping. I found out the
> IC-746PROs did not have any path to discharge the antenna charge from
> the snow static.
>
> I recently installed the KPA100 Upgrade and one of the steps was to
> remove R10 the 100uh choke between the antenna jack and ground. There is
> no other path to ground and I have read on the reflector about people
> having their SWR and Power measuring diodes go bad and it was easy to
> see why. I plan to use this rig to check into the ND Weather net this
> winter so knew I needed to fix the problem.
>
>
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