Hi Bob,
Thanks for the help. I have a guy with a rig on the 2nd floor using home made
ladder line consisting of #12 wire spaced a 4in. Feedline runs perhaps 10 ft
before it splits off (corner fed) into the loop.
No balun at all. Fed right off the ladder line. I suspect the length of the
loop may have to be adjusted. Short of hanging line out of a second floor
window, I don't have a clue how to add more feed line.
73 de Phil - N8PS
----------
Quoting Bob McGraw - K4TAX <RMcGraw@Blomand.net>:
> I would change the length of the feed line by 20 or so feet. Either add or
> take away. I do hope the feed line is reasonably straight an if there is
> any excess is not in a "coil" somewhere.
>
> Also, are you using a 4:1 balun or a 1:1 balun? And are these voltage
> baluns or current baluns? I find that 1:1 current baluns work better in
> most cases unless one is feeding something like a folded dipole where the
> impedance is close to 200 to 300 ohms. In this case a 4:1 works better.
>
> Based on what you describe, I suspect that you are using a 4:1 balun. That
> device doing it's job and presuming the load Z at the feed line at the
> transmitter end is say 25 ohms then the 4:1 balun is making that look like
> 6.25 ohms. Most tuners have a problem with this. Therefore a 1:1 balun
> would present a 25 ohm load to the tuner. Much better.
>
> 73
> Bob, K4TAX
>
>
>
>
> ----- Original Message -----
> From: "Phil Sussman" <psussman@pactor.com>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Wednesday, January 21, 2009 7:15 PM
> Subject: [TenTec] Antenna question
>
>
> > This may be a bit off-topic - If so please forgive me:
> >
> >
> >
> > I'm working with a fellow who has problems loading an 80M loop antenna
> > with
> > ladder line and a tuner. His antenna is about 380ft and I think that it's
> > a bit
> > short. I borrowed my Nye-Viking and the best that I can achieve is 3 to 1
> > match
> > at 3800 KHz.
> >
> > At that point the tuner is applying MINIMUM capacitance. That makes me
> > think
> > that a longer antenna length is needed.
> >
> > As an aside 40m loads no better 2.5 to 1, but 30m loads up OK.
> >
> > If I take his balanced line and feed it as a long wire (one end
> > unterminated)
> > the system loads up just fine on 40m and 80m, but it is obviously
> > unbalanced.
> >
> > Any quick hints appreciated -- I'm not the best with HF antennas.
> >
> > PS. My 80m loop antenna is 420ft long and loads as balanced just fine.
> >
> > de Phil - N8PS
> >
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|