Topband: Need antenna advice

[Guy Olinger K2AV]

What tugs at my gut most is that you may have placed insulated radials
down on the snow , using the dimensions in the links for laying on the
ground.

The velocity factor of wires laying on the ground can be anywhere
between .45 and .7, just depending on the dirt and what's down in it,
and how close you actually are to the dirt itself (think lawns).
That's why the plan has you cutting back the radials to 98 feet.

HOWEVER, the velocity factor starts to rise quickly even a half inch
above the ground.  If you put them on snow, you need longer radials to
be resonant. If you are on 6 inches of snow, I'd guess the velocity
factor is more like .9 or .95.

That being the case, the radials would be too short, the current sink
would appear more to be your ground rod (not good), and/or your
feedline. The effect would be a very broad match that is blowing most
of your power in the ground.

Take an analyzer, treat the two radials like a dipole and see where
they resonate. Adjust the length to resonate on 160.  Note that this
will drift as the snow melts.

Do something more permanent and reliable in the spring.

73, Guy.

On Thu, Feb 11, 2010 at 11:07 PM, Mike Waters W0BTU
<mrscience65704 at yahoo.com> wrote:
> Ok, I feel a little foolish asking this question, but I wonder if anyone on the Topband list can offer some suggestions as to why my transmitted signal on 160 might be so weak.
>
> I can hear very, VERY well on 160. I am in a very quiet location, and I have two 2-wire bi-direction Beverages which hear VERY well. I've been playing with receiving antennas on 160 for a long time, and I decided it was finally time to see what I could accomplish on 160. But after finally erecting a transmitting antenna, my signal on 160 is very weak to every person I've ever tried to work. DX and stateside, CW and SSB. I put up the best xmit antenna that was possible at this time of year, just before the CQ 160 contest.
>
> I can only run 100 watts at this time.
>
> I tried the inverted-U antenna as described in the links below. It is very similar to the one that K3LR used in the first link. The antenna is over the top of a 60' oak tree, and the two elevated radials are about 10' high.
>
> I'd put down a lot of radials and a top-loaded T antenna, but that's just not possible with the weather this time of year.
>
> Am I expecting too much with just 100 watts? I don't think so; I've heard of many hams working DXCC without an amplifier. It was my intention to get a transmitting antenna working well at the 100 watt level, and then building a legal limit amplifier.
>
>
> I've operated 3.5 through 144 MHz since 1976, but this is the worst experience I have ever had since I've been licensed. I know this is almost a stupid question, but I have to ask it before I go crazy.
>
> Thanks in advance for your patience, gentlemen. :-)
>
> 73,
> Mike Waters
> W0BTU
>
>
>
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