On Sep 22, 12:04*am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Sun, 21 Sep 2008 18:47:13 -0700 (PDT), Knight
>
> <petelar...@comcast.net> wrote:
> >> Incidentally, I've now built about 6 assorted AMOS/Franklin antennas
> >> including some really weird constructs. *They all work just fine,
> >> although the higher gain versions required using a sweep generator to
> >> accurately adjust the center frequency.
>
> More links on AMOS and Franklin antennas from my messy bookmark
> collection:http://yu1aw.ba-karlsruhe.de/ANT.htmhttp://yu1aw.ba-karlsruhe.de/vhf_ant.htmhttp://www.qsl.net/yu1aw/vhf_ant.htmhttp://www.brest-wireless..net/gallery/AntenneAmoshttp://www.brest-wireless.net/wiki/materiel:amoshttp://pe2er.nl/wifisector/
>
> >If you look at my sector here *http://img.villagephotos.com/p/2003-8/361947/IMG_7445(Medium).JPG
> >You'll notice that the copper tubing is soldered to the "N" female
> >connector underneith and also to the main board.
>
> Looks about right. *What type of coax is that shoved into the copper
> tube? *It kinda looks like aluminum foil outer shield, which won't
> work because it can't be soldered. *You don't really need the shield
> on the coax as the copper tube provides that function.
The coax is LMR-400 with outer coating and braid removed. To much
hassle to remove the foil
so I left it on, makes a tighter fit anyway. But since the tubing is
soldered to the connector
AND the reflector then can I just solder the Balun shield/braid to the
copper tubing?
>
> Also, that's a Radio Shock soldering iron which is grossly
> underpowered for soldering large "heat sink" type PCB's, connectors,
> and coax cables. *My guess(tm) it's 35w at best. *You need something
> like a 60watt or higher iron, with thermostat control at 850F, and a
> wide chisel tip. *The soldering looks like the results of trying to
> solder the new and disgusting lead-free solder at too low a
> temperature. *Use a hot iron, flux if necessary, and work fast.
Have you been reading my mind? I've been pondering for days now which
iron to get from this site here...
http://www.action-electronics.com/solderingirons.htm
My God there are so many to choose from though!
What do you like for this kind of work?
The iron in the photo is a Sears 45 W. It just about almost does it
so I
was thinking a nice 60 Watt should be fine, do you?
>
> >I saw diagrams how to solder the shielding together at the Balun but
> >since I'm soldered to the connector AND
> >the backplane then would it be safe to say that I can then solder the
> >Balun shielding straight
> >to the copper tubing?
>
> Yep. *It's all one big solid ground (shield) around the center coax.
> The trick is to keep the shield end points of the balun fairly close
> together. *Everything else can be somewhat creative. *Use the photo
> at:
> <http://pe2er.nl/wifisector/>
> for a guide. *Note that the center coax cable has no shield or shield
> braid inside the copper tube.
>
> >I also changed the design of the biquad. What do you think now?
> >http://img.villagephotos.com/p/2003-8/361947/DXNHA-IMG_7461(Medium).JPG
>
> Check the dimensions of the PCB reflector. *It doesn't look quite
> right. * Hard to tell from this small a photo.
Yeh the reflector is ok. It's 123mm X 123mm
>
> >http://img.villagephotos.com/p/2003-8/361947/FTWLS-IMG_7459cropped.jpg
>
> Clever idea, but un-necessary. *The only thing that's really critical
> on the biquad is the *LENGTH* of the loop on each side. *You can be
> very creative with the shape, but not the length. *The length is
> measured from where the two loops hit each other plus any length added
> from exposed center conductor and shield conductors. *The center pin
> connection is correct, but you've effectively added a tiny amount of
> length to the ground side. *It's probably not critical as the antenna
> is fairly broadband, but it will tend to lower the optimum center
> frequency slightly. *You can shorten both loops to compensate, but I
> would just shorten the ground extension and solder the two loops to
> ground slightly lower on the copper tube. *Yeah, I know it doesn't
> look as aesthetically perfect that way, but it should work slightly
> better.
>
> Note that it's not super critical and will probably work as you built
> it. *There were a bunch of construction articles on biquads that
> totally dispensed with the copper tube coax cable extension and
> replaced them with a thin wire. *I originally declared this to be
> technically disgusting and suggested that it be done correctly. *I
> then modeled the antenna and found that it still had all of the usual
> +8dBi gain, but that the VSWR was considerably higher. *That will
> create some losses, but is not totally fatal. *So, even built wrong,
> it will still work.
>
> The right way:
> <http://802.11junk.com/jeffl/antennas/Biquad/>
>
> The wrong way:
> <http://802.11junk.com/jeffl/antennas/biquad-junk/>
>
> Also, the soldering in the closeup is atrocious but not unexpected
> considering the new lead-free solder and the cold soldering iron.
> Wiggle the wires and the solder connection will probably break. *Try
> to make it look smooth and shiny. *Note that mixing solder types will
> result in a guaranteed dull and brittle connection. *Don't do it.
I pull real good on the connections before I sell! They're on there
good
but I know what you mean about being nice and shiny. Better iron
will that for sure. Help me out with a good selection on a decent
iron
if you have a minute.
And what about solder? Any recomendations?
>
> >http://img.villagephotos.com/p/2003-8/361947/JYXIY-IMG_7459(Medium).JPG
>
> What are you using for insulators at the ends? *It kinda looks like a
> dark color, which might be carbon filled nylon (anti-static). *Those
> will work, but you really want something that is a good RF insulator,
> such as PTFE or coax dielectric. *Nylon is hygroscopic (absorbs
> moisture) and will cause problems if used outdoors.
The insulators are plastic tubing. Not sure what kind but feels like
tubing
you would use for your ice maker in your freezer.
Twist ties coming up from bottom.
>
> >I really appreciate and respect your input sir'
>
> Easy on the "sir" thing. *It might make me more arrogant, if that's
> possible.
Ha Ha ok Dude! LOL
Pete
>
> --
> Jeff Liebermann * * je...@cruzio.com
> 150 Felker St #D * *http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann * * AE6KS * *831-336-2558