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Re: [Amps] L4-B

To: amps@contesting.com
Subject: Re: [Amps] L4-B
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Mon, 31 Mar 2014 21:38:38 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>

On 3/31/2014 9:19 PM, Paul Christensen wrote:
> In another life, I recall changing out the Kapton blocker in a Harris
> FM-35K.

They were used the both the plate blocker and screen bypass in the RCA
F and G lines of VHF TV transmitters IIRC - but that was a lifetime
ago.  I certainly remember changing them when rebuilding PA cavities.

73,

   ... Joe, W4TV


On 3/31/2014 9:19 PM, Paul Christensen wrote:
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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