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Johnny
Fed Up. Bye.
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join:2001-06-27
Atlanta, GA
kudos:2

SO-239: which side to solder vertical element to?

In the video below, the guy has attached the vertical element (12 gauge solid copper) to this SO-239 connector.

I'm pretty sure but not certain that he soldered it to the pin that was on that side, rather than to the female side.

Photo:




In the video, it's at approx 19:42 that he shows the connector with the element already soldered on.

»www.youtube.com/watch?v=cFp8CYLf ··· 8CYLfq0c


Can anybody verify?


drjim
Premium,MVM
join:2000-06-13
Long Beach, CA
kudos:3
It solders to the center pin.

The sides of the connectors are where you attach the radials.
--
One man's Magic is another man's Engineering.

Phillip
I Need A Nap

join:2004-12-21
Hatboro, PA
reply to Johnny
It is inserted and soldered to the center pin in the pic and video. Some 239 have a small solder cup and do require you to solder the wire to the side of the pin.


Johnny
Fed Up. Bye.
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Atlanta, GA
kudos:2
reply to drjim
Thanks for confirmation.


Johnny
Fed Up. Bye.
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Atlanta, GA
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reply to Phillip
said by Phillip:

It is inserted and soldered to the center pin in the pic and video. Some 239 have a small solder cup and do require you to solder the wire to the side of the pin.

Well, I have 2 ordered and hope the pin accepts the 12 ga. wire.


John Galt
Forward, March
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join:2004-09-30
Happy Camp
kudos:8
You can use 14 ga. if you need to. Wire gauge is not significant from an RF/electrical standpoint.

tobicat
Premium
join:2005-04-18
Tombstone, AZ
reply to Johnny
I have made lots of those. If you want the wire to be stiff and not flop around. Go to a box store to the welding section and get a couple of pieces of brazing rod.


Johnny
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Atlanta, GA
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said by tobicat:

I have made lots of those. If you want the wire to be stiff and not flop around. Go to a box store to the welding section and get a couple of pieces of brazing rod.

Does that come in different diameters? If not, is the standard diameter small enough to slide into that pin?


John Galt
Forward, March
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join:2004-09-30
Happy Camp
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You can also use brass tubing. It would slide over the center conductor pin. Hold the tubing back from the base a smidge and the solder will flow into it nicely.


Johnny
Fed Up. Bye.
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Atlanta, GA
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reply to Johnny
Hmmm... I was just reading that this connector is not ideal for 70 cm band use unless it has Teflon dielectric and silver plate.

Not really a problem as I planned it for 2m use.


drjim
Premium,MVM
join:2000-06-13
Long Beach, CA
kudos:3
The Type "UHF" connector was designed back in the 1930's, when anything over 200Mc was considered "UHF".

True, they don't present a 50 Ohm impedance through them, and a mated pair has a definite impedance 'bump', but people have been using these things for years at 70cm.

Just go ahead and use it. While you could measure a difference with lab-grade gear, you'd probably never notice it in real world use.
--
One man's Magic is another man's Engineering.


Johnny
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Atlanta, GA
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Ah, that's reassuring.

Once I get this thing assembled I've got a way to use the local club's (NF4GA) MFJ analyzer just to make sure, at least on 2 meters.

Question: since this design relies on the ground, is it still acceptable to place it in an attic? Or should another design be used in that capacity?


drjim
Premium,MVM
join:2000-06-13
Long Beach, CA
kudos:3
The 4 radials that you install on the corners of the SO-239 flange will be your "ground", or, more accurately, the "counterpoise".

It should work fine up in the attic as long as you don't have any foil-backed insulation in the roof.

What type of feedline (coax) are you using, and how many feet of it?
--
One man's Magic is another man's Engineering.


Johnny
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said by drjim:

The 4 radials that you install on the corners of the SO-239 flange will be your "ground", or, more accurately, the "counterpoise".

It should work fine up in the attic as long as you don't have any foil-backed insulation in the roof.

I don't think so - don't remember installing anything like that.

What type of feedline (coax) are you using, and how many feet of it?

12 feet of RG-8x with the PL-259s on each end.

Is there any need for grounding or lightning protection for an attic placement? There are no openings in the walls or ceiling, and no other antennas anywhere.


drjim
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join:2000-06-13
Long Beach, CA
kudos:3
Well....you NEED them.

If all you have is the coax running up to the SO-239, and all it has is a single wire sticking out of it....it AINT gonna work!

You need something like this:
--
One man's Magic is another man's Engineering.


Johnny
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Atlanta, GA
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Right. I have 50' of 12 gauge wire. I'll attach 4 pieces to the corners of the SO and one vertically. Then hook up the analyzer and check the SWR, trim some length if needed, before transmitting on it.

I was just asking if there is any additional thing I need to connect. I don't think so.


drjim
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join:2000-06-13
Long Beach, CA
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OK...understood.

As far as lightning protection, I wouldn't think so if it's in the attic.
--
One man's Magic is another man's Engineering.


Johnny
Fed Up. Bye.
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Atlanta, GA
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1 recommendation

I completed it and put a borrowed analyzer on it. SWR 1.1 to 1.4 on 146 mHz, and 1.5 on UHF (70 cm). Not bad.