Posted by
Kenneth Christiansen on
Oct 24, 2010; 12:56am
URL: http://elecraft.85.s1.nabble.com/Prevent-Snow-Dirt-Static-damage-to-KPA100-after-upgrade-tp5666395p5666702.html
Hi Don
Thank you for your note. You answered a question that was on my mind and
in fact I did use the slavaged RFC10 in my own modification. I put it
across J4 the RF IN jack of the KAT100. It seems to work fine and I plan
to keep it that way. The only reason I did not put it in my note was
that I was not sure why it was removed from the KPA100 in the first
place. Now that I know I recommend either putting the RFC10 accross J4
of the KAT100 like I did or putting RFC10 from the center pin to ground
of the PL-259 and T adaptor.
Thanks for the info Don and I hope between our two notes we can save
many KPA100s from snow static this winter.
73
Ken W0CZ
+++++++++++++++++++++++++++++++++++++++++++++++
On 10/23/2010 7:25 PM, Don Wilhelm wrote:
> 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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