[Elecraft] Blown trap?

[David Cole]

Hi,

No matter what happens, you will probably end up taking the antenna
down...  If nothing else to check to be sure it is fine...

Grab an analyzer and connect it as close to the antenna base as
possible, and see if it is resonant on all bands...  Probably won't
anymore.  If you are lucky, it is some strange feedline thing, or a
connector issue, but having the antenna work on some bands, while not on
others reeks of blown trap.  I fear your diagnosis is in fact
correct...  

If you are going to "fix" it, and if it were me, I would get a trapless
antenna of some sort...  No traps blow.  I currently use a GAP
Challenger DX, (trapless), and have a band by band review of it at:
http://nk7z.net/review-of-the-challenger-dx-antenna-by-gap-antenna/

The antenna takes power, and does not break, I have run 1000 Watts into
it on RTTY for 15 minutes with no issues.  I have had it up for at least
7 years, and I think 10 or more years.  Never a problem beyond the three
radials coming off once...  It is a pretty good performer on 40, and 20.
I finally got one of the mono gaps, and it does a good job.  I do take
it down every few years and check things, and change out anything that
looks like it is going bad.

-- 
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net
for MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
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http://groups.yahoo.com/neo/groups/dopplergram/info
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On Mon, 2014-12-15 at 12:17 +0200, Vic Rosenthal 4X6GP/K2VCO wrote:
> Here is my somewhat off-topic question for today:
> 
> I have an R8 vertical, which does its bandswitching with a combination 
> of stubs and traps. The other day I was transmitting CW on 40M with 
> about 1200 watts and a normal SWR of less than 1.5:1. Suddenly the SWR 
> went sky-high. Now the antenna doesn't work on 7 and 10 MHz, although it 
> is fine on the higher bands. It looks to me like I blew the 30M trap. So:
> 
> 1. Do you folks think this is a correct diagnosis? I will have to take 
> the antenna down to be sure, and that won't be fun since it is on top of 
> a 10-story building.
> 
> 2. I have heard of this happening with the R8, although it is rated at 
> 1500W CW according to the manual. But I always thought the people it 
> happened to were operating at high SWRs. Maybe these are 1500 MFJ watts, 
> which, as everyone knows, are smaller than regular watts. Has anyone had 
> a similar experience?
> 
> 3. Should I have bought a KPA500 which wouldn't stress the antenna as 
> much? :-)