Re: LF: XPQ WSPR15 475/136 and warm ceramic feed thrus

["Alan Melia" <alan.melia@btinternet.com>]

Hi Laurence my book gives Stainless Steel as 8 times  resistivity of Brass and 40 times  that of pure copper so maybe you were pushing your luck a bit, though I would have thought the connections at the ends would be problem. It looks like arcing on the pic but its obviously not..... the eramoc got so hot is just melted its  way though the plastic and it is cooked plastic on the outer surface. Also its not bulk resistance at these freqs you have to consider skin effect in the SS. Still interesting its only one insulator. It might be interesting to look at it with a milliohm meter if you have such a beast. I would guess you must have had the equivalent of 0.2 ohm or so to get that hot....particularly in your climate :-))

 

Alan

G3NYK

----- Original Message -----

From: Laurence KL7 L

To: rsgb_lf_group@blacksheep.org

Sent: Saturday, October 24, 2015 11:05 PM

Subject: RE: LF: XPQ WSPR15 475/136 and warm ceramic feed thrus

Thanks Alan - th iono really hadnt cooled off up here from the continuous heating over the past month or so but it was getting better so I thought Id better inject a little more heat

http://kl7l.com/coupler3.jpg

The Stainless 5/16th bolt in the feedthru must have had some imperfections in manufacture and got extremely hot at circa 50-60A :-) it didnt happen to the other bolt and wasnt at the wire connection points each side.

 I think Ive had it with feed thrus' at this current and are going to come straight in thru a hole drilled in a hi density cutting board. 

I recall the original brass feed thrus getting a little warm but this must have got real warm - sufficient to say the Decca kept on transmitting and didnt see a high SWR at all over the past week...

The Walmart Rubbermaid box was (is)  in its 12th year and Im just going to plate over it... :-)

Laurence KL7L WE2XPQ

---

From: alan.melia@btinternet.com
To: rsgb_lf_group@blacksheep.org
Date: Sat, 24 Oct 2015 22:42:47 +0100
Subject: Re: LF: XPQ WSPR15 475/136

Hi Markus, yes I think that has been happening, but in Laurence's case the first post did not appear to any of us so that was probably bounced on theway in, but I have seen cases were posts have been reflected but not received by the sender. Some ISPs seem to regard a message sent to self as spam.....I regularly dig out my LF postings from my webmail spam folder. Marking them as "Not Spam" does not seem to affect the rules in "Spamguard", the filter used.

 

I reckon you are due for a few down days Laurence the CME from the C5 on the 22nd arrived at 1900z. Spaceweather maked it as arriving unexpectedly early.....I dont see that the interval was about 62 hours. We only caught the "wash" as it was not pointing at Earth, and that could account for some of the longer interval.

 

Alan