[Amps] L4-B

[Joe Subich, 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.

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 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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