One failure mode was when the cavity spark-gap took a lightning hit
and a ball of molten brass rolled up against the plate blocker and
burned a hole in the Kapton. solved by making a 4 layer catch trough
out of Kapton below the spark-gap. Changing that blocker with the
nylon rails was a pita, for sure.
Quoting Paul Christensen <w9ac@arrl.net>:
In another life, I recall changing out the Kapton blocker in a
Harris FM-35K. It hadn't failed in 24/7 service at 12KV, but a
service bulletin in the late'80s called for doubling-up on the
sheets to increase the breakdown voltage. A single sheet was likely
fine but where routine maintenance is lacking, an an accumulation of
dirt/dust probably resulted in a few field failures.
Paul, W9AC
-----Original Message----- From: donroden@hiwaay.net
Sent: Monday, March 31, 2014 9:09 PM
To: amps@contesting.com
Subject: Re: [Amps] L4-B
Harris uses a sheet of it between the cavity and a large square piece
of aluminum for a coupling capacitor @ 11KVDC + RF . Continental
wraps it around a two piece stovepipe attached to the plate of a
4CX35000 in their design again 11KV DC + RF. Pretty tough stuff.
Don W4DNR
Quoting Michael Tope <W4EF@dellroy.com>:
It is used pretty extensively in the flight hardware that JPL
builds for space. I know for a fact there was a bunch used on the
landing radar for the Curiosity rover. I am sure there is a bunch
of it on the rover as well. In fact, I would be real surprised if
there are any JPL spacecraft in service that don't use at least
some of the stuff.
On earth people use duct tape, in space they use Kapton tape :-)
73, Mike W4EF................
On 3/31/2014 4:33 PM, Bryan Swadener wrote:
Yes, really.
We used it for decades, in both tape form and Kapton-insulated
wire form, in critical applications at the world's largest OEM
of RF-driven sealed CO2 Lasers.
The stuff is VERY tough. The only way we found to remove
the insulation from wire ends was by blasting it with one of our
more powerful (> 100W) Lasers or, by mechanically scraping it off.
vy 73,
Bryan WA7PRC
--------------------------------------------
On Mon, 3/31/14, Mark Bitterlich wrote:
Subject: Re: [Amps] L4-B
To: Bryan WA7PRC, amps@contesting.com
Date: Monday, March 31, 2014, 4:26 PM
Really? Interesting.
Just FYI, Kapton insulated wire was removed from ALL
military aircraft after some very impressive tests were done
showing how it
tended to blow and burn under certain conditions. Of
course, that was the
Kapton insulated wire. I know zip, nada, ZERO about
the tape. Possibly it
is A-OK.
v/r,
Mark Bitterlich
WA3JPY
----- Original Message -----
From: Bryan WA7PRC
To: <amps@contesting.com>
Sent: Monday, March 31, 2014 7:18 PM
Subject: Re: [Amps] L4-B
> Also, Kapton(tm) aka polyimide tape will work FB.
> It works well at high temperature and high voltage.
>
> vy 73,
> Bryan WA7PRC
> --------------------------------------------
>
>
> Date: Sun, 30 Mar 2014 23:07:13 -0500
> From: Edwin Karl
> To: amps@contesting.com
> Subject: [Amps] L4-B
>
> Just be very careful with the power resistors used in
the
> bias cutoff/
> bleeder
> They are mounted on long screws that run through the
center
> of the
> resistor. In
> repairing an amplifier for a buddy, I had the
resistors
> short through the
> porcelain of the resistor.
>
> The fix is use good 3m glass tape to insulate the
screw, and
> enough on
> the ends to insure centering the resistors. Unlike
> electrical tape,
> glass tape
> is rated at 240 degrees and will withstand the high
heat.
> Make sure to
> reinstall
> the mica insulators.
>
> Good Luck!
> We're all counting on you ...
>
> 73
>
> Ed K0Kl
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