The idea is that the choke passes essentially no current at the
frequency of operation, but is essentially a dead short at DC.
Unless I'm remembering the formula wrong, which is always a possibility,
the choke has a reactance of about 28k ohms at 1.8 MHz, which means that
it would have about 10 mA through it if you had it across a 50-ohm
feedline being driven at 1500W. I'm pretty sure that would work without
letting the smoke out. Since that's the most difficult case (higher
frequencies have more reactance and, hence, less current) it should work
on most any band. Up until you hit the resonant frequency of the choke,
anyway.
Another technique you can use is to put a large resistor across the
feedline. Since you're only trying to prevent tiny amounts of charge
from accumulating, that should work, too. 300K or larger should be able
to dissipate the power from a legal-limit signal. Unless I did the
calculation wrong.
On 5/24/2016 11:52 AM, n5xz via BVARC wrote:
Would this be suitable for legal limit (or more)?
Did a search on the choke: https://www.tubesandmore.com/products/P-C1535B
Travis
K5HTB
________________________________________
From: BVARC <bvarc-boun...@bvarc.org> on behalf of Sam Neal via BVARC
<bvarc@bvarc.org>
Sent: Monday, May 23, 2016 7:50 AM
To: BRAZOS VALLEY AMATEUR RADIO CLUB
Cc: Sam Neal
Subject: Re: [BVARC] Bleeding static from antennas
Hello,
Consider placing a 2.5 mH RF choke from the antenna to ground. Keep it
in a
dry place. Many of the old boat-anchor transmitters did this from the
antenna
coax connector to ground to protect the operator or anyone from
touching the
antenna should the RF coupling capicator between the tube plate and
the pi-net
tuner open up placing B+ on the antenna.
73,
Sam Neal N5AF
Sent from my Verizon Wireless 4G LTE smartphone
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--
Jonathan Guthrie KA8KPN
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