[Amps] L4-B

[donroden at hiwaay.net]

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 at 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 at hiwaay.net
> Sent: Monday, March 31, 2014 9:09 PM
> To: amps at 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 at 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 at 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 at 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 at 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
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>
>>
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>
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