Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Homebrewing 160m veritcal ?'s  (Read 2556 times)
N3NEP
Member

Posts: 13




Ignore
« on: June 12, 2013, 08:02:14 AM »

Hi,
  I have recently built a coil for 80m to be used with an Ldg S9v43 43' vertical antenna.  It was my friend Jerry W0ZD/3 design that I copied & it works very well. The second part of this project was to develop a way to make it work on 160m too.  My friend has been busy at work and hasn't had time to work on that part of the project yet. I believe his thoughts were to wrap some toriods with wire rather than building/adding a new copper coil. I did see what he had started and it was about 4 torroids wrapped with some white insultaing tape which was then wrapped with some high quality wire.  I am not very educated in electrical theory but I am very mechanically capable and can follow instruction very well.  I am wondering if someone has attempted this already and could share with me the design I would be very happy to be able to complete the 160m part of this project before the end of the summer. I have included a link of a picture that shows my current setup for 80m.

Thanks
Scott
N3NEP



http://i158.photobucket.com/albums/t87/pistollovr/IMG_0546_zps08cd0fa3.jpg
 
Logged
KB4QAA
Member

Posts: 2295




Ignore
« Reply #1 on: June 12, 2013, 11:25:01 AM »

The very simplest approach is to make another coil, or add to the one you have so it's roughly double the size for 160m.

Buying toriods is going to be rather expensive compared to a few dozen feet of copper wire mount on some plastic form.
Logged
WX7G
Member

Posts: 5920




Ignore
« Reply #2 on: June 12, 2013, 04:58:02 PM »

To load a 43' vertical on 1.8 MHz requires a series inductance of 60 uH. A shunt inductor of roughly 5 uH across the feedpoint will transform the low input input impedance to 50 ohms.

The adjustment of the inductors interact but it isn't too difficult to tune this antenna.

The main inductor can be as simple as stranded, insulated #14 THHN (house wire) close-wound on a 2" PVC pipe. About 80 turns - that's about 8" of of the form - will provide some extra inductance that can be tuned as needed.
Logged
N3NEP
Member

Posts: 13




Ignore
« Reply #3 on: June 12, 2013, 05:37:48 PM »

Thanks, I pretty much assumed I could add another coil but I hoping to get some input on how to make/assemble the
toriods. I haven't done anything with them and thought it would be an interesting project.  The cost isn't too much of
an issue if I can get the parts needed for around $50. I think I can build another coil for about $15 but I have already done
that and so I was looking to learn something from working with the toriods.  If anyone has built an antenna using the toroid
approach and could breakdown the building process I would be grateful for some instruction.

Thanks
Scott
N3NEP
Logged
K3VV
Member

Posts: 13




Ignore
« Reply #4 on: June 12, 2013, 06:43:29 PM »

Here's an thread that's worth reading ...

http://forums.qrz.com/archive/index.php/t-297395.html
Logged
K3VAT
Member

Posts: 701




Ignore
« Reply #5 on: June 12, 2013, 06:51:07 PM »

<snip> ...   If anyone has built an antenna using the toroid approach and could breakdown the building process I would be grateful for some instruction. Thanks Scott N3NEP

Scott,

You can use toroids, however, as WX7G intimated using the coil approach is easier and less expensive.  You can simply do trial-and-error winding or unwinding coils as needed to bring your antenna to the desired freq.  The same holds for the shunt inductor: use trial-and-error to wind or unwind coils for feedpoint transformation.  One can experiment with different sized coils - the larger diameter coil and larger diameter wire tends to be more efficient, especially if the form factor ends up being around 1:2 (the length is twice the coil diameter) and the spacing between the wires is the same as the diameter of the wire (plus insulation).

GL, 73, Rich, K3VAT
Logged
WB6BYU
Member

Posts: 13040




Ignore
« Reply #6 on: June 12, 2013, 08:43:10 PM »

The number of turns required to wind a coil will depend on the size and type of the
toroid cores you are using.  The type 2 (red) cores are often used because they are
more common, but the type 15 (red/white) cores are somewhat better at 160m, as
they have 2.5 times the permeability and so require fewer turns for the same inductance.

You can find all the information you need to wind your coils at the Amidon website:
www.amidoncorp.com/specs/

Let's take an example:  looking at the tables for type 15 material here:
http://www.amidoncorp.com/product_images/specifications/1-07.pdf
the AL value for a T-130-15 core (the 130 tells you it is 1.3" in diameter) is 250uH/100 turns.
Inductance goes up by the square of the number of turns, so we can calculate the required
number of turns for a 60 uH coil as follows:

ratio of desired inductance to AL value = 60 / 250 = 0.24

number of turns required = square root ( 0.24 ) * 100 turns = 49 turns. 

That's probably too many to put on a core and still use fat enough wire, so let's try stacking
4 cores.  That multiplies the AL value by 4 (approximately).  Now we have a value of
1000uH / 100 turns.  Repeating the calculations:

ratio of desired inductance to AL value = 60 / 1000 = 0.06

number of turns required = square root ( 0.06 ) * 100 = 25 turns.

That's getting more practical, though it gives you a relatively large change in inductance
when you change the number of turns by 1.  You might want to make a "main coil" with
4 cores that has just enough inductance to resonate the antenna at the top end of the
band (or a bit above that), and then use a second coil on a single core to give smaller
inductance steps for fine tuning, putting both coils in series.  You can then place taps
around the smaller coil to resonate the antenna in different parts of the band.  You can
also experiment with connecting the bottom of the coil to ground and tapping your coax
a couple turns up the coil from there to provide matching to 50 ohms.

There are similar charts available for the type 2 material, which is available in larger sizes
(up to 5.2" diameter) than the type 15 (maximum size 1.57").  In spite of the larger size,
the AL value doesn't get much larger than that of the single T-130-15 core, so you'll
still need about the same number of turns, but it is easier to fit them on the larger core.

Logged
AD5X
Member

Posts: 1426




Ignore
« Reply #7 on: June 13, 2013, 05:06:08 AM »

Check out my 160/80M matcher for 43-footers in the "Articles" section of my website at www.ad5x.com.73.  I originally published this as a 2-part article in QST.  I've recently rebuilt it and made it easier to duplicate by documenting it better as you can see in the article.

Phil - AD5X
« Last Edit: June 13, 2013, 05:08:36 AM by AD5X » Logged
KC4MOP
Member

Posts: 729




Ignore
« Reply #8 on: June 13, 2013, 05:23:18 AM »

Check out my 160/80M matcher for 43-footers in the "Articles" section of my website at www.ad5x.com.73.  I originally published this as a 2-part article in QST.  I've recently rebuilt it and made it easier to duplicate by documenting it better as you can see in the article.

Phil - AD5X
Hey Phil the link does not work. It would be interesting to see your approach.....maybe remove the dot 73 part of the URL???
Logged
N3NEP
Member

Posts: 13




Ignore
« Reply #9 on: June 13, 2013, 05:54:46 AM »

Thanks these responses are more along the line of what I was hoping to get. Dale your info is especailly good to know and also helps me understand the method of figuring the whole toroid thing out.  Phil I will visit your site and check out the info there too.  Thanks to all who have contributed.  I appreciate all the input and look forward to putting some time in at the bench building.

73
Scott
N3NEP  Grin
Logged
K4SAV
Member

Posts: 1831




Ignore
« Reply #10 on: June 13, 2013, 07:13:35 AM »

At a power level of 100 watts, assuming a ground loss of 8 ohms, the voltage across the coil will be about 1675 VRMS on 160 meters.  The largest single core I could find was 4 inches in diameter.  Using the Mini Ring Core Calculator, shows that with a T400-2 the core flux is approximately 109 and the temperature rise of the core is 66 deg C.  The max core flux that the T400 can handle is 110, so it is at max with 100 watts.

Is that your Alpha 78 in those pictures?  If so forget the toroid.  You would need probably 15 of those T400 toroids.

If you do use high power and an air coil, the voltage across the coil (assuming 8 ohms of ground loss and 1 ohm of coil loss) should be about 8750 V peak.  Corona will be a big problem, especially with high humidity.
http://www.w8ji.com/loading_inductors.htm

Jerry, K4SAV

http://www.dl5swb.de/html/mini_ring_core_calculator.htm
« Last Edit: June 13, 2013, 07:23:49 AM by K4SAV » Logged
N3NEP
Member

Posts: 13




Ignore
« Reply #11 on: June 13, 2013, 08:04:43 AM »

I don't have the Alpha anymore I have a Command Technologies Commander HF 2500 Magnum. Same difference though.

Thanks
Scott
N3NEP
Logged
KF5RGB
Member

Posts: 16




Ignore
« Reply #12 on: June 13, 2013, 10:08:22 AM »

I recently ran into the same dilemma wanting to be able to operate my my zero five 43 vertical on 160. i was tempted to try experimenting and building my own coils and such but decided to be lazy and ordered an MFJ-2902 (43VERT 160M RANGE EXTENDER) instead last week..........

http://www.mfjenterprises.com/Product.php?productid=MFJ-2902

They also make a 2904 model that's good for 1500 watts. I cant vouch for them as I haven't received my item yet (its on backorder) but I'll leave an update when I get it and install it if anyone's interested. Before I ordered I searched all over for reviews on the thing also but had no results.
Logged
AD5X
Member

Posts: 1426




Ignore
« Reply #13 on: June 13, 2013, 11:32:39 AM »

Check out my 160/80M matcher for 43-footers in the "Articles" section of my website at www.ad5x.com.73.  I originally published this as a 2-part article in QST.  I've recently rebuilt it and made it easier to duplicate by documenting it better as you can see in the article.

Phil - AD5X

Sorry - Not sure how that 73 got in there.  The website is www.ad5x.com.  Got to the "Articles" section.  I had an earlier unit that used a T400A-2 core.  But the mini-ring calculator showed this to be a problem at higher power levels.  The air-wound inductor I use in the current article is much better.

I also have an autotuner extender article, which it appears that MFJ based their unit on.  Mine is remote-switchable using a vacuum relay.

Phil - AD5X
« Last Edit: June 13, 2013, 11:35:43 AM by AD5X » Logged
KF5RGB
Member

Posts: 16




Ignore
« Reply #14 on: June 13, 2013, 05:23:54 PM »

I also have an autotuner extender article, which it appears that MFJ based their unit on.  Mine is remote-switchable using a vacuum relay.

Phil - AD5X

I thought them call letters sounded familiar, before I ordered the one from MFJ, I browsed your site and  checked out that article, sounds like your the one who needs to be selling them. Darn thing is on 2-4 week backorder.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!