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Homemade Sigma 4 11 meter base antenna

W5LZ said:
Well, from their instructions it doesn't seem like they think it's necessary. Try it, see what happens. Then try it the other way and see what happens. If it made their antenna significantly better, I would think they would recommend insulating it, wouldn't you?
- 'Doc
Click to expand...

I could ask Sirio but they haven't returned my last two emails. I'll check my junk mail.
 
Lil'Yeshua said:
I could ask Sirio but they haven't returned my last two emails. I'll check my junk mail.
Click to expand...

Update:I emailed Sirio again.
Didn't HomerBB mount it both ways? I think he had problems zeroing it in being electrically connected to the mast. That would change how it performs. The 4000's radials are on the ground side of the gamma match.
 
I'm wondering of I even need an antenna tuner. I contacted MFJ Enterprises and asked their advice. Here's their reply.
best selling manual tuner is the mfj-949e, $179.95. 12 position switched inductor, antenna switch, built-in dummy load, 3 inch cross needle swr wattmeter, handles 300 watts pep ssb, 1.8 to 30 mhz.

without the dummy load, the mfj-948 is $159.95.

a smaller 200 watt version is the 941E, $139.95.
http://www.mfjenterprises.com/Product.php?productid=MFJ-949E
http://www.mfjenterprises.com/Product.php?productid=MFJ-948
http://www.mfjenterprises.com/Product.php?productid=MFJ-941E
http://www.mfjenterprises.com/Product.php?productid=MFJ-1702
 
Last edited:
The bandwidth of my Qv4k.

MFJ readings:


------ E1/2 wave jumper --------------------- 89' feed line in the shack
SWR
2.0 -- 28.374 --- R75 -- X19 ------------------- 28.569 --- R35 -- X18
1.5 -- 27.960 --- R56 -- X21 ------------------- 27.942 --- R86 -- X0
1.1 ----------------------------------------------- 27.385 --- R57 -- X4
1.0 -- 27.564 --- R54 -- X0 ------------------------------------------
1.0 -- 27.387 --- R56 -- X0 ------------------------------------------
1.5 -- 26.893 --- R72 -- X14 ------------------- 26.509 --- R56 -- X23
2.0 -- 26.515 --- R103 - X0 -------------------- 25.957 --- R127 - X0

You'll have to decide whether you want to use a tuner to go where you want to go on the band.
 
HomerBB said:
The bandwidth of my Qv4k.

MFJ readings:


------ E1/2 wave jumper --------------------- 89' feed line in the shack
SWR
2.0 -- 28.374 --- R75 -- X19 ------------------- 28.569 --- R35 -- X18
1.5 -- 27.960 --- R56 -- X21 ------------------- 27.942 --- R86 -- X0
1.1 ----------------------------------------------- 27.385 --- R57 -- X4
1.0 -- 27.564 --- R54 -- X0 ------------------------------------------
1.0 -- 27.387 --- R56 -- X0 ------------------------------------------
1.5 -- 26.893 --- R72 -- X14 ------------------- 26.509 --- R56 -- X23
2.0 -- 26.515 --- R103 - X0 -------------------- 25.957 --- R127 - X0

You'll have to decide whether you want to use a tuner to go where you want to go on the band.
Click to expand...

I bet they're neat to use. I have a MFJ-207 I just bought. Gonna use that to tune my 4000,5000,pig,cat,dog,coat hanger. :)(y)
 
I've been thinking. On the lower telescoping sections,if I pop riveted them instead of supplied screws or stainless steel clamps(higher wind load),and treat the mated sections with NO-OX-ID,that might be a sleek way to do it plus it would be all shiny and have a lower CD coefficient after being polished.
 

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I would think twice before pop-riveting anything you may want to take loose later. As for the anti-oxidizing goop, just remember that it will eventually wear/wash off. In most cases, with a good mechanical connection, it isn't going to make a huge difference in performance. It does help though, so have at it.
- 'Doc
 
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Maybe you should think about making it stronger instead of sleeker.
I have used pop rivets in other applications before, and thought of using them for antenna work but rejected the idea. Like Doc said, if it holds then you'll have to file it apart to get it apart.
I would use either the screws or the SS clamps, the clamps only, or both the screws and the clamps before I used pop rivets. The wind will wallow the soft aluminum of those pop rivets apart or loose in due time.

Be sure to take some Ibuprofen before you sleep tonight. It should help the headache all your thinking must certainly be giving you.
 
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No ibuprofen needed! I was unsure about pop rivets. You would have to place one at a right angle relative to the other to minimize the chance of the union working loose. I read the application claims on the NO-OX-ID. It's electrically conductive plus it has anti oxidation properties. Has anybody used this stuff(No-od/
-id)in compliance with the product's instructions? They said it stays on fir decades. But all in all,I'm asking questions from those who have experience and I appreciate it. Thanks.
 

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