RE: [HCDX] Winding high Q BCB coils ??

["Charles Hutton" <charlesh3@xxxxxxx>]

I'd modify the 1026 as per the info at http://www.w8ji.com/mfj-1025_1026.htm
and see where that gets you. The design is certainly not optimum from a
strong signal handling point of view, and these mods will help.


Chuck Hutton

-----Original Message-----
From: hard-core-dx-bounces@xxxxxxxxxxxxxxxx
[mailto:hard-core-dx-bounces@xxxxxxxxxxxxxxxx]On Behalf Of J999w@xxxxxxx
Sent: Tuesday, January 28, 2003 6:46 PM
To: hard-core-dx@xxxxxxxxxxxxxxxx; amfmtvdx@xxxxxxxxxxxxxxx
Subject: [HCDX] Winding high Q BCB coils ??


I'm trying to construct a BCB preselector to eliminate overload of my
MFJ1026
by local transmitters. I'm currently using coils taken from discarded
portable AM radios, but I would like better selectivity (higher circuit Q).

For example, using a series LC circuit peaked on 760khz, my pest on 1290khz
is decreased by about 10-15db. That helps, but the pest can still be heard
on
some frequencies. A parallel trap using the same components set for 1290khz
will cut it down about 25db, but the loss is devastating down on 760khz.

Has anyone played around with spider wound or honeycomb wound coils with
Litz
wire in home construction??

I found this link on crystal sets that seems helpful:
http://home.t-online.de/home/gollum/hcoils.htm

Size really isn't important, but high Q with low loss is !

73,

John Wilke
WB9UAI

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THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at http://dsl.org/copyleft/dsl.txt