That IS a good question.
Anyone have any typical plots?
I have read that use of a lossy line will lessen the depth of the notch,
but it will also broaden it too. depending on operating practices a
trade off?
maybe optimize them? since for the 40 meter stub, cut it first shorter
say for 7225 KHz, 269.66 inches. with a like BNC connector on the end.
Then make up a short connector, that adds about 7 more inches to it to
drag the null down to 7050 or so?
This also makes it possible to make a shorted connector too to short the
ends when needed to make it the 20 meter null.
Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 5/6/2013 9:55 PM, Charles Harpole wrote:
Further question..... with a correctly made stub, what is its band of
protection? 50kc from the design frequency or 100kc or more still provides
null protection?????????
Charly
On Mon, May 6, 2013 at 7:49 PM, Joe <nss@mwt.net> wrote:
Getting ready for Field Day here.
The only bands we seem to have problem on are 40 & 20 with the two
stations hearing each other.
So plan on making up a pair of stubs, for each station.
Now from wat i have found seems pretty simple. and will this actually be
correct?
It looks like the 1/4 wave (electrical) on 40 un shorted will block 0 an
pass 20 yes?
and the exact same stub shorted will pass 40 and block 20 yes?
so adding at the far end a small SPST toggle switch should make a easy
switch 20 or 40 stub yes?
Now I plan on using them in the usual manner right at the rigs with a "T"
connector.
To make them we plan on using a MFJ 259B
The way they say to make a stub using it is pretty plain and straight
forward and easy, "BUT"........
I'm assuming I should include the "T" when making the stub to have it
include the extra length it is making.
Now what do I do with the open end of the "T"?
does it need to me terminated? like with a 50 ohm dummy load? o9r left
open is ok, or what?
Anyone?
Joe WB9SBD
For Field Day The Yellow Thunder Amateur Radio Club
WB9FDZ
The field Day Zombies
--
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
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