Thread: Homebrew traps
View Single Post
  #25   Report Post  
Old March 31st 08, 05:05 PM posted to rec.radio.amateur.antenna
Jim Lux Jim Lux is offline
external usenet poster
 
First recorded activity by RadioBanter: Mar 2007
Posts: 801
Default Homebrew traps

Cecil Moore wrote:
Barrett wrote:

Some one sent me an email and said these will do the job. Ceramic
capacitor disk 10KV/1000pF. Do you think these would work?



I don't know about those particular ones. Some ceramic
capacitors are meant to be DC biased for bypass service.
I once tried to use disc ceramic caps across my ladder-
line. They caught on fire because they were not rated for
AC service and lit up the night sky.

Someone told me the ceramic insulator was actually
trying to physically vibrate at the RF frequency and
friction heated it up.


That's basically what's going on. It's actually the ferromagnetic
domains doing the vibrating in the ceramic (i.e. there's no physical
displacement), but it's the losses in that vibration that's responsible
for the dissipation.


I don't know if your capacitors
are rated for AC operation.

A friend of mine used silver mica capacitors for his
traps and they worked fine.


Silver mica works fairly well at HF (assuming you stay within the
ratings).. mica is a low loss dielectric