[TowerTalk] TowerTalk Digest, Vol 225, Issue 29
Joe Locascio
pvjoe at yahoo.com
Thu Sep 23 12:10:36 EDT 2021
Try Tom Shiller, N6BT the designer/builder of those Antennas. Last time I know of his 'whereabouts' was in KINGMAN, AZ; Check on his QRZ page for more info.
Good luck es 73
Joe K5KT
On Thursday, September 23, 2021, 09:01:23 AM PDT, <towertalk-request at contesting.com> wrote:
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Today's Topics:
1. Old Force 12 C3-SS info needed (Eric Rosenberg)
2. T-Network Calculator Spreadsheet (David Gilbert)
3. Re: Old Force 12 C3-SS info needed (john at kk9a.com)
4. Re: T-Network Calculator Spreadsheet (Richard (Rick) Karlquist)
5. Re: T-Network Calculator Spreadsheet (Jim Brown)
6. Re: T-Network Calculator Spreadsheet (David Gilbert)
7. Re: Old Force 12 C3-SS info needed (Stan Stockton)
----------------------------------------------------------------------
Message: 1
Date: Wed, 22 Sep 2021 23:54:40 +0000
From: "Eric Rosenberg" <ericrosenberg.dc at gmail.com>
To: "towertalk at contesting.com" <towertalk at contesting.com>
Subject: [TowerTalk] Old Force 12 C3-SS info needed
Message-ID: <em12f5755e-350c-4977-b81c-171344f2797f at eric>
Content-Type: text/plain; charset=utf-8; format=flowed
The element and boom to mast clamps on my 20 year old Force 12 C3-SS are
very rusty and need to be replaced.
Nowhere in the construction/instruction manual do I see where size size
is specified.
Does anyone have that information?
For that matter, if anyone has suggestions on what mods/fixes I should
make on this antenna, which hasn't been touched since I put it up a long
time ago, please pass them along.
Thanks & 73,
Eric W3DQ
Washington, DC
------------------------------
Message: 2
Date: Wed, 22 Sep 2021 19:12:41 -0700
From: David Gilbert <ab7echo at gmail.com>
To: Towertalk <towertalk at contesting.com>
Subject: [TowerTalk] T-Network Calculator Spreadsheet
Message-ID: <c659514e-9b16-ec26-8382-65f93dabda0d at gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
There are several online T-Network and L-Network calculators out there,
as well as various standalone applications that do the same thing.? My
problem with most of them, though, is that every time I change the
frequency or change the complex load values (or typically both), the
network gets recalculated for the new values.? That isn't necessarily
the real world, though, where fixed networks might be used at the
feedpoint of an antenna or somebody just doesn't want to bother retuning
the network every time they change the frequency. What I wanted to see
was what happened to impedances, currents, and voltages when the network
didn't change but everything else did.
So I wrote a simple spreadsheet to show that sort of thing.? It's
nothing special ... literally just the application of Ohms Law using
complex impedances ... but the calculations get messy enough that it's
much easier handled using the available formulas in Excel.
I'm pretty certain that applications like the excellent AutoEZ and EZNEC
can display a similar output for fixed tuner values based upon an
antenna model, but this spreadsheet is useful when you have an antenna
that isn't easy to model and you are able to obtain the actual feed
impedances as a function of frequency using one of the relatively
inexpensive complex impedance analyzers that are available now.? Looking
at you, nanoVNA.
I've made the spreadsheet freely available for download from the files
page of the Arizona Outlaws Contest Club website.? Go to:
http://www.arizonaoutlaws.net/??? then click on "Downloads" under the
"More" drop down tab at the top of the page.
Using the spreadsheet should be pretty obvious, but the first sheet
("Intro") has some explanatory text.? The sheet titled "AB7E" has the
calculator.? To be clear, this spreadsheet does NOT give you the
optimized network values for any particular frequency and load, although
you can get there by trial and error if you so choose.? You can easily
get the automatically optimized values elsewhere, such as from TLW, the
free transmission line calculator that comes free with the ARRL Antenna
Book.? But once you load those values into the spreadsheet for one
frequency you can see what happens for other frequencies and loads.
The spreadsheet was written in Excel 2010 to handle ten columns of input
data, but a simple copy/paste will extend that to however many data
points you might want to use.
The spreadsheet is set up as a T-Network, but by simply setting one of
the capacitors to a very high value (like 50,000 pf) that element will
look like a short and the network becomes essentially an L-Network.? You
could even do the same for a single series or shunt element using the
same idea ... make the other values high enough that they don't matter.
The spreadsheet assumes a 50 ohm non-reactive source impedance.? I could
have written it for an arbitrary complex source impedance, but that
would require the assumption that the source is able to output the
stated power at that impedance.? I didn't think that was necessarily
realistic, but if anyone thinks that would be especially valuable, drop
me a note.
If the spreadsheet turns out to be useful to you, hug somebody you
haven't hugged in a while.
73,
Dave?? AB7E
------------------------------
Message: 3
Date: Wed, 22 Sep 2021 22:38:30 -0400
From: <john at kk9a.com>
To: <towertalk at contesting.com>
Subject: Re: [TowerTalk] Old Force 12 C3-SS info needed
Message-ID: <002f01d7b024$18cf50b0$4a6df210$@com>
Content-Type: text/plain; charset="us-ascii"
If I recall the element to mast clamp is just a formed aluminum plate
riveted to the boom with u-bolts clamping the element. If that is correct
the only thing that could corrode is the u-bolt. Force 12 did not seem to
like using stainless steel u-bolts. If the u-bolt is the only issue it is
pretty easy to measure them (check the bracket hole spacing too) and
purchase stainless steel replacements at McMaster-Carr, etc.
John KK9A
Eric Rosenberg W3DQ wrote:
The element and boom to mast clamps on my 20 year old Force 12 C3-SS are
very rusty and need to be replaced.
Nowhere in the construction/instruction manual do I see where size size
is specified.
Does anyone have that information?
For that matter, if anyone has suggestions on what mods/fixes I should
make on this antenna, which hasn't been touched since I put it up a long
time ago, please pass them along.
Thanks & 73,
Eric W3DQ
Washington, DC
------------------------------
Message: 4
Date: Wed, 22 Sep 2021 20:25:13 -0700
From: "Richard (Rick) Karlquist" <richard at karlquist.com>
To: David Gilbert <ab7echo at gmail.com>, Towertalk
<towertalk at contesting.com>
Subject: Re: [TowerTalk] T-Network Calculator Spreadsheet
Message-ID: <b83ed43e-6be6-17ff-082b-895069184a72 at karlquist.com>
Content-Type: text/plain; charset=utf-8; format=flowed
I usually use Simsmith for this sort of analysis. I believe it
imports "touchstone" files from your VNA, etc. Why reinvent the
wheel?
73
Rick N6RK
On 9/22/2021 7:12 PM, David Gilbert wrote:
>
> There are several online T-Network and L-Network calculators out there,
> as well as various standalone applications that do the same thing.? My
> problem with most of them, though, is that every time I change the
> frequency or change the complex load values (or typically both), the
> network gets recalculated for the new values.? That isn't necessarily
> the real world, though, where fixed networks might be used at the
> feedpoint of an antenna or somebody just doesn't want to bother retuning
------------------------------
Message: 5
Date: Wed, 22 Sep 2021 21:50:04 -0700
From: Jim Brown <jim at audiosystemsgroup.com>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] T-Network Calculator Spreadsheet
Message-ID:
<d7052b39-f3f9-f161-ce33-310b443fbebb at audiosystemsgroup.com>
Content-Type: text/plain; charset=utf-8; format=flowed
On 9/22/2021 8:25 PM, Richard (Rick) Karlquist wrote:
> I usually use Simsmith for this sort of analysis.? I believe it
> imports "touchstone" files from your VNA, etc.? Why reinvent the
> wheel?
Same here. Freeware, runs in Java.
73, Jim K9YC
------------------------------
Message: 6
Date: Wed, 22 Sep 2021 21:58:10 -0700
From: David Gilbert <ab7echo at gmail.com>
To: "Richard (Rick) Karlquist" <richard at karlquist.com>, Towertalk
<towertalk at contesting.com>
Subject: Re: [TowerTalk] T-Network Calculator Spreadsheet
Message-ID: <cfeab060-6e42-c8a0-f287-870ee73db2c3 at gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
You didn't actually look at the spreadsheet, did you ...
Dave?? AB7E
On 9/22/2021 8:25 PM, Richard (Rick) Karlquist wrote:
> I usually use Simsmith for this sort of analysis.? I believe it
> imports "touchstone" files from your VNA, etc.? Why reinvent the
> wheel?
>
> 73
> Rick N6RK
>
> On 9/22/2021 7:12 PM, David Gilbert wrote:
>>
>> There are several online T-Network and L-Network calculators out
>> there, as well as various standalone applications that do the same
>> thing.? My problem with most of them, though, is that every time I
>> change the frequency or change the complex load values (or typically
>> both), the network gets recalculated for the new values.? That isn't
>> necessarily the real world, though, where fixed networks might be
>> used at the feedpoint of an antenna or somebody just doesn't want to
>> bother retuning
------------------------------
Message: 7
Date: Thu, 23 Sep 2021 03:15:05 -0500
From: Stan Stockton <wa5rtg at gmail.com>
To: Eric Rosenberg <ericrosenberg.dc at gmail.com>
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Old Force 12 C3-SS info needed
Message-ID: <26956A20-D813-4CFB-8CB5-47ECDE623A49 at gmail.com>
Content-Type: text/plain; charset=utf-8
Eric,
I think at minimum I would replace whatever you are using for a balun with something new and up to date from an engineering standpoint. There aren?t any 20 year old balun designs, whether a coil of coax or something using ferrite, you would want to use on a new antenna going up today.
JK antennas has taken this antenna design and made changes to improve the performance using computer modeling which is better than whatever method was used to design the original antenna. There would be no question in my mind about which design would provide better results, particularly SWR curves. I would find out exactly what modifications are needed to duplicate the JK antenna design.
Here is what you should expect with those changes.
https://jkantennas.com/c3s-jk.html
73? Stan, K5GO (ZF9CW)
> On Sep 22, 2021, at 6:54 PM, Eric Rosenberg <ericrosenberg.dc at gmail.com> wrote:
>
> ?The element and boom to mast clamps on my 20 year old Force 12 C3-SS are very rusty and need to be replaced.
>
> Nowhere in the construction/instruction manual do I see where size size is specified.
>
> Does anyone have that information?
>
> For that matter, if anyone has suggestions on what mods/fixes I should make on this antenna, which hasn't been touched since I put it up a long time ago, please pass them along.
>
> Thanks & 73,
>
> Eric W3DQ
> Washington, DC
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
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End of TowerTalk Digest, Vol 225, Issue 29
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