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From: Laurence KL7 L <hellozerohellozero@hotmail.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Date: Sat, 24 Oct 2015 19:38:08 -0800
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Subject: RE: LF: XPQ WSPR15 475/136 and warm ceramic feed thrus
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I seem to remember taking out the feedthrus and rods down in Okie - but I t=
hink they were copper/brass and still got warm.

Odd stuff this RF...  I measured the DC resistance of the 5/16th SS and it =
was 14.4 milliohm at DC=3B as the other rod was "ok" Im thinking I had some=
thing else going on that side of the feed - the good thing is the Loop is f=
loating relative to Earth so it could have been worse.=20

So Ive plated out the hole and run thru new cable and connectors to the bus=
 bars and its back to how it was in Okie=2C save I dont have multiple loop =
conductors and that 1dB "gain" but I have to be realistic with the trees he=
re.

Back up and running on WSPR 15 and IR Laser showing air temp +38F=2C toriod=
 at 54F (15 mins at 800W)=2C and caps generally around 40-42F so looks beni=
gn. The loop conductor is a few degrees warmer in free air with the current=
 running thru it -

Im sure stainless hardware is generally fine but avoid it if its in the RF =
path - thanks for the story John -=20

Sure was a great melt down - Ive binned the ceramic feed thru as the glazin=
g had become sintered or breached with some form of chemical reaction from =
the plastics vapor Im guessing - probably Cyanide :-(

Thanks for all the feed back -  this isnt the first RF  hot component this =
enclosure has had in its LF/MF life - probably wont be the last either... c=
ome home to a real fire

Laurence KL7L WE2XPQ -

=20

From: w1tag@charter.net
Date: Sat=2C 24 Oct 2015 20:13:25 -0400
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: XPQ WSPR15 475/136 and warm ceramic feed thrus

I remember a graveyard maintenance shift many years ago=2C when my boss obs=
erved that a braid wire connection clipped onto a coil in a MF power divide=
r was looking kind of shabby. Not being able to find a piece of flat copper=
=2C he tried length of stainless steel "Wraplock"=2C which started out nice=
 and shiny. After a few minutes of operation=2C it got very warm=2C and tur=
ned black. We quickly located some copper.=20
John=2C W1TAG
 		 	   		  =

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<body class=3D'hmmessage'><div dir=3D'ltr'>I seem to remember taking out th=
e feedthrus and rods down in Okie - but I think they were copper/brass and =
still got warm.<br><br>Odd stuff this RF...&nbsp=3B I measured the DC resis=
tance of the 5/16th SS and it was 14.4 milliohm at DC=3B as the other rod w=
as "ok" Im thinking I had something else going on that side of the feed - t=
he good thing is the Loop is floating relative to Earth so it could have be=
en worse. <br><br>So Ive plated out the hole and run thru new cable and con=
nectors to the bus bars and its back to how it was in Okie=2C save I dont h=
ave multiple loop conductors and that 1dB "gain" but I have to be realistic=
 with the trees here.<br><br>Back up and running on WSPR 15 and IR Laser sh=
owing air temp +38F=2C toriod at 54F (15 mins at 800W)=2C and caps generall=
y around 40-42F so looks benign. The loop conductor is a few degrees warmer=
 in free air with the current running thru it -<br><br>Im sure stainless ha=
rdware is generally fine but avoid it if its in the RF path - thanks for th=
e story John - <br><br>Sure was a great melt down - Ive binned the ceramic =
feed thru as the glazing had become sintered or breached with some form of =
chemical reaction from the plastics vapor Im guessing - probably Cyanide :-=
(<br><br>Thanks for all the feed back -&nbsp=3B this isnt the first RF&nbsp=
=3B hot component this enclosure has had in its LF/MF life - probably wont =
be the last either... come home to a real fire<br><br>Laurence KL7L WE2XPQ =
-<br><br>&nbsp=3B<br><br><div><hr id=3D"stopSpelling">From: w1tag@charter.n=
et<br>Date: Sat=2C 24 Oct 2015 20:13:25 -0400<br>To: rsgb_lf_group@blackshe=
ep.org<br>Subject: Re: LF: XPQ WSPR15 475/136 and warm ceramic feed thrus<b=
r><br><div>I remember a graveyard maintenance shift many years ago=2C when =
my boss observed that a braid wire connection clipped onto a coil in a MF p=
ower divider was looking kind of shabby. Not being able to find a piece of =
flat copper=2C he tried length of stainless steel "Wraplock"=2C which start=
ed out nice and shiny. After a few minutes of operation=2C it got very warm=
=2C and turned black. We quickly located some copper.&nbsp=3B</div><div><br=
></div><div>John=2C W1TAG</div><br></div> 		 	   		  </div></body>
</html>=

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