Re: LF: Take care lads, grass fire here...

[Andy Talbot <andy.g4jnt@gmail.com>]

Never use nylon as an RF insulator,  it's horribly lossy.  Back in the 73kHz days I used nylon strimmer cord  as an insulator for my Tee antenna; 200Watts and about 15kV on the antenna.  One day , in wet weather, after a prolonged transmission Pout suddenly dropped and I saw the antenna had fallen down.   The nylon had just melted.  Presumably a combination of lossy material and damp helping tracking.

Replaced with a decent ceramic dog-bone at each end and its been fine ever since - nearly 20 years

Andy  G4JNT

On 23 June 2017 at 15:50, John Andrews <w1tag@charter.net> wrote:

Chris,

I recall throwing snowballs at a flaming tree one winter evening. Small fire -- mostly the insulation on the wire for my loop antenna. But the tree bark had definitely joined the blaze.

So, it's not just hot, dry wx. LF and fire are close friends.

John, W1TAG

On 6/23/2017 10:10 AM, Chris Wilson wrote:

Hello LF`ers,

     Just made a quick test WSPR TX here and the wind has got up here.
     First TX was fine, second one, luckily whilst I was watching the
     Scopematch, suddenly went odd. Shut it down and went outside, to
     find the nylon fishing line tether for the vertical wire had
     broken and the vertical had set light to the dry grass strimmings
     near the loading coil. Luckily I managed to stamp it out otherwise
     the green wheelie bin with the loading coil in it would have
     caught too. Deep scorch marks on a wooden post that stops the
     wheelie bin blowing over as well, from arcing from the vertical
     wire. Take care in this dry weather especially if the wind gets
     up..... :)