Knut and all,
Yes, BUT...
Lightning is a static charge which *will* produce transients in the
antenna system. As will wind static, rain static and snow static.
Large voltages can build up on the antenna and feedline, and will remain
until dissipated. Sort of like a charged capacitor that holds that
charge until dissipated. Some of those events can produce very large
voltages.
So yes, I believe it is a matter of semantics. Charges of any kind on
the antenna feedline can cause damage. The K3 has more protection than
the K2/KPA100, but that does not make it immune to all events.
Have you ever touched across the terminals of a feedline after a nearby
lightning event and felt a 'tickle' or even worse? I have, and it is
not nice. A bleeder resistor of 2500 ohms to 50k across the feedline
will bleed off a static charge in short order.
Even with a lightning suppression device in the feedline, there is still
a threshold voltage that it responds to. At voltages less than that
threshold, the protection device will not be of any assistance in
bleeding off the charge.
73,
Don W3FPR
On 1/21/2018 4:42 PM, ab2tc wrote:
Hi Don and all,
I really don't understand why static build up on the antenna should be a
problem with the K3. Due to the (good) design of the SWR bridge (a two
transformer design with a voltage transformer right across the output) the
antenna port presents a dead short circuit at DC both in receive and
transmit. I just verified this with an ohm-meter (in receive only - no need
to check in transmit since the SWR bridge is surely present then - don't
want to kill my DMM).
Maybe we are talking semantics here but it appears to me that the cause of
diode damage in the SWR bridge circuit is more likely caused by transients
induced into the antenna system by nearby lightning strikes than static
buildup.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
