auto-disconnect antenna relays? (KAT100 related)

[Chris Kantarjiev K6DBG]

I've just replaced the 1N5711 SWR diodes in my KAT100 for the Nth time. It's annoying, but I guess
it's not annoying enough to cause me to disconnect my antennas every time I turn off the radio!

Here in "northern" California, we don't have many thunderstorms, but apparently we get enough wind
static to damage these diodes once every year or so. I really wish there was an idiot-proof way to
disconnect the antennas without any intervention on my part!

A small box that was powered from my 12v distribution panel and has two suitable relays in it would
be welcome. I guess I could make it myself, but I wonder if anyone else has already done so, in a
way that integrates cleanly to the KAT100 outputs? I wouldn't want them in the KAT2, since I operate
from battery at times. But when I'm running the KAT100, I am using more power than I have battery ...

(Does the K3 have such relays in the output circuitry?)

73 de chris K6DBG
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[Andreas Junge]

Chris,

how about a 1Meg OHM resistor between the center of the coax connector
and ground. That should bleed off the static, but not mess with the
impedance.

Andreas, N6NU

On Sat, 2009-10-10 at 19:27 -0700, Chris Kantarjiev wrote:

> I've just replaced the 1N5711 SWR diodes in my KAT100 for the Nth time. It's annoying, but I guess
> it's not annoying enough to cause me to disconnect my antennas every time I turn off the radio!
>
> Here in "northern" California, we don't have many thunderstorms, but apparently we get enough wind
> static to damage these diodes once every year or so. I really wish there was an idiot-proof way to
> disconnect the antennas without any intervention on my part!
>
> A small box that was powered from my 12v distribution panel and has two suitable relays in it would
> be welcome. I guess I could make it myself, but I wonder if anyone else has already done so, in a
> way that integrates cleanly to the KAT100 outputs? I wouldn't want them in the KAT2, since I operate
> from battery at times. But when I'm running the KAT100, I am using more power than I have battery ...
>
> (Does the K3 have such relays in the output circuitry?)
>
> 73 de chris K6DBG
> ______________________________________________________________
> Elecraft mailing list
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[David Gilbert]

Even better would be a surge protector with a shunt inductor designed
for pretty much that exact task.  I have no connection with I.C.E. but
$40 seems a reasonable enough price.

http://www.iceradioproducts.com/impulse1.html#1

Static accumulation from overhead clouds can be huge even without a
lightning strike.  I generally short the shack end of all my coax runs
when a storm approaches, but one day a couple of years ago I was slow
doing so and when I reached for the coax I got zapped with a bright blue
2 inch long arc to my left hand (my right hand was touching the concrete
floor).  Both biceps were sore for three days afterward.

I'm not sure I'd want to trust one megohm to draw off the static charge
quickly enough to keep the voltage from creeping high enough to damage
the rig.  I've seen arcs jump across the end of an unterminated PL-259
literally every five seconds.  Give me the DC short any day.

73,
Dave   AB7E



Andreas Junge wrote:

> Chris,
>
> how about a 1Meg OHM resistor between the center of the coax connector
> and ground. That should bleed off the static, but not mess with the
> impedance.
>
> Andreas, N6NU
>
> On Sat, 2009-10-10 at 19:27 -0700, Chris Kantarjiev wrote:
>  
>> I've just replaced the 1N5711 SWR diodes in my KAT100 for the Nth time. It's annoying, but I guess
>> it's not annoying enough to cause me to disconnect my antennas every time I turn off the radio!
>>
>> Here in "northern" California, we don't have many thunderstorms, but apparently we get enough wind
>> static to damage these diodes once every year or so. I really wish there was an idiot-proof way to
>> disconnect the antennas without any intervention on my part!
>>
>> A small box that was powered from my 12v distribution panel and has two suitable relays in it would
>> be welcome. I guess I could make it myself, but I wonder if anyone else has already done so, in a
>> way that integrates cleanly to the KAT100 outputs? I wouldn't want them in the KAT2, since I operate
>> from battery at times. But when I'm running the KAT100, I am using more power than I have battery ...
>>
>> (Does the K3 have such relays in the output circuitry?)
>>
>> 73 de chris K6DBG
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>    
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Please help support this email list: http://www.qsl.net/donate.html
>
>  

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[Ken Kopp-3]

I've had a pair of 2.5 mH RF chokes from each side
of my open-wire feeder to ground for years.  This
provides a DC path to ground with no apparent ill
effects. Seems to work. Like a lightning rod, one
doesn't know if it works until it doesn't. (;-)

I assume that the same would work for a single
coax center conductor.

Yes, I know there is a likelihood for this to "mess
with the impedance", but I've seen no problem
because of this arrangement. YMMV

73! Ken Kopp - K0PP
     [hidden email]


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