[SI-LIST] (No Subject)
- From: "GEORGE VARGHESE" <rfengg@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 10 Mar 2003 18:04:20 +1100
Steve,
Thanks for your mail. Further to your reply:
"You must also consider the electric field effects. In practice you will also
increase the capacitance to ground from the coils turns. If you think of this
in very simple terms you have a coil with lots
of capacitors in parallel with it to ground. At some frequency you will see a
parallel resonance of the coil inductance and this stray capacitance. The
reactance increase at high frequency you are seeing
could be the coil resonance with the stray capacitance. "
I have a concern with this Steve.You are right in that I will have a coil with
lots of capacitors to ground when I shield it with some copper.( why is a
floating shield referenced ground ????)However this causes a series capacitance
with the coil to ground and will cause a series resonant circuit at some
frequency rather than a parallel resonant one. Correct me if I am wrong , but
the parallel SRF of an inductor arises from the parallel turns to turns
capacitances ; the capacitances to ground cause series resonance. ( I have seen
this (burnt out ) effect in high power vaccuum RF amp Chokes where the choke
inductance has to be large due to the high operating plate
resistances; any ground's close to the choke cause series resonance and burn up
due to the low reactance path.)
regards,
George.
_____________________________________________________________
Get 25MB, POP3, Spam Filtering with LYCOS MAIL PLUS for $19.95/year.
http://login.mail.lycos.com/brandPage.shtml?pageId=plus&ref=lmtplus
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
