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CX2SA > SATDIG 10.10.14 14:10l 221 Lines 5855 Bytes #999 (0) @ WW
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From: CX2SA@CX2SA.SAL.URY.SOAM
To : SATDIG@WW
Today's Topics:
1. How you wind it (Robert Bruninga)
2. Re: How you wind it (i8cvs)
3. N. Europe on AO-7 (Bob- W7LRD)
4. AMSAT INDIA Website - New Look (Nitin Muttin)
----------------------------------------------------------------------
Message: 1
Date: Thu, 9 Oct 2014 10:04:34 -0400
From: Robert Bruninga <bruninga@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] How you wind it
Message-ID: <59efb44fee420aef0a22f49aac5362a7@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
How you wind a coil makes a BIG difference.
Ever wonder why your projects don?t work like the authors?
Im winding 42 turns onto a 1 Megohm 1/4W resistor to make a loading coil to
make a 5? whip antenna on a cubesat tune to 28 MHz.
I was getting nowhere trying to add and subtract turns. With a bandwidth
of only 200 kHz it was inconsistent getting to 28.120 center freq.
Then I simply took the same length of wire and tried 3 methods all with the
same number of turns.
1, down-and-back-and forward for 3 layers = 24.5 MHz
2, left-to-right but scrambled 3 layers along the way = 30.0 MHz
3, just a little squeezing of turns that had loosend = 28.8 MHz
Wow, just changing the winding method moves the 0.2 MHz bandwidth as far as
30-to-1!
The difference of course is the stray capacitance between the end turns.
So winding method is important!
Just thought I?d share the results?
Bob, WB4APR
------------------------------
Message: 2
Date: Thu, 9 Oct 2014 20:43:46 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
To: "Robert Bruninga" <bruninga@xxxx.xxx>, <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] How you wind it
Message-ID: <001101cfe3f0$f6a3f470$0401a8c0@xxxxx>
Content-Type: text/plain; charset="UTF-8"
Hi Robert, WB4APR
Don't forget that if you have wonded the coil over a 1 Megohm
1/4 W resistor if it is a spiralized type resistor it has a small
inductance that at the end of the job is connected in parallel
to the your copper wind affecting the final value of the total
inductance.
To tune exactly the inductance to 28 MHz is suffice to
cover the inductance with a small soft copper foil and solder
it only at one end of the resistor and cut and try with it's
lenght.
Best 73" de i8CVS Domenico
----- Original Message -----
From: "Robert Bruninga" <bruninga@xxxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Sent: Thursday, October 09, 2014 4:04 PM
Subject: [amsat-bb] How you wind it
> How you wind a coil makes a BIG difference.
>
> Ever wonder why your projects don?t work like the authors?
>
>
>
> Im winding 42 turns onto a 1 Megohm 1/4W resistor to make a loading coil
to
> make a 5? whip antenna on a cubesat tune to 28 MHz.
>
> I was getting nowhere trying to add and subtract turns. With a bandwidth
> of only 200 kHz it was inconsistent getting to 28.120 center freq.
>
>
>
> Then I simply took the same length of wire and tried 3 methods all with
the
> same number of turns.
>
>
>
> 1, down-and-back-and forward for 3 layers = 24.5 MHz
>
> 2, left-to-right but scrambled 3 layers along the way = 30.0 MHz
>
> 3, just a little squeezing of turns that had loosend = 28.8 MHz
>
>
>
> Wow, just changing the winding method moves the 0.2 MHz bandwidth as far
as
> 30-to-1!
>
>
>
> The difference of course is the stray capacitance between the end turns.
>
> So winding method is important!
>
>
>
> Just thought I?d share the results?
>
>
>
> Bob, WB4APR
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
expressed
> are solely those of the author, and do not reflect the official views of
AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 3
Date: Thu, 9 Oct 2014 19:10:31 +0000 (UTC)
From: Bob- W7LRD <w7lrd@xxxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] N. Europe on AO-7
Message-ID:
<1651856441.4547567.1412881831278.JavaMail.root@xxxxxxx.xxx>
Content-Type: text/plain; charset=utf-8
I have been in contact (email) with several European stations.? I am always
looking for? dx opportunities on AO-7.? If you see that chance drop me a
email for possible QSO.? I can usually acquire AO-7 at about 2-3 degrees.
73 Bob W7LRD
Seattle, Wa.
CN87wk
------------------------------
Message: 4
Date: Fri, 10 Oct 2014 17:45:10 +0800
From: Nitin Muttin <vu3tyg@xxxxx.xx.xx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] AMSAT INDIA Website - New Look
Message-ID:
<1412934310.40584.YahooMailNeo@xxxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=utf-8
We have published a new website of AMSAT INDIA. I have been personally
working on this for quite some time. This new design permits us to publish
updates and carry out changes with ease removing the dependency on an
external source.
Over a period of time we will add more content and feature's . Suggestions
are welcome.
Visit - www.amsatindia.org
The nameserver change to our new web host takes ~24 hours to propagate to
DNS servers worldwide. If you are unable to see the new website please try
after some time.
73
Nitin [VU3TYG]
Secretary, AMSAT INDIA
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx.
AMSAT-NA makes this open forum available to all interested persons worldwide
without requiring membership. Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 9, Issue 350
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