Sal M. Onella wrote:
"JIMMIE" wrote in message
oups.com...


snip

One thing that
concerned me even after the antenna was working is the SWR
appeared to be a little too good. It was 1.2:1 in the middle of 10
meters and never got ave 1.7:1 even at the band edges. I thought that
this is a little too good to be true..

My concern, too, for the same reason but the readings appear to be
authentic. For check, I tried the modified antenna (coax not running
through the lower element) on a few other bands with very, very low power
and got terrible VSWR readings. I get about a 1.4:1 at the low end of the 10
band, dropping to a 1.1:1 near the top of the band. I believe having big,
fat elements helps.

Due to cable loss, my measured VSWR at the transceiver is a skosh better
than what I would see at the antenna. A nice chart in the ARRL Antenna Book
shows that with 1 dB cable loss (approximate for 100' of RG-8), my 1.4:1
VSWR measured at the radio is actually closer to 1.6 at the antenna. Still a
keeper. I went on the air last night with a few watts and got a great
signal report from a local ham, so the antenna is working.

"Sal"
(KD6VKW /AE)




A year or two ago I was into playing with various monopole designs for
10 meters and greater freqs.

The bazooka I built and liked was a stainless steel whip for the
radiator. The bazooka sleeve was hook to coax and the mast--at the
sleeve where the bottom of the radiator was mounted on a teflon block
insulator. The sleeve was either 1-1/8 or 1-3/8 copper pipe.

The antenna was fed at the top of the sleeve where the radiator exited,
with a 1:1 current balun on a toroid core. The balun was able to handle
100+ watts and I drove it at 100 W.

The swr was below 1.5:1 on most of the ten meter band, I don't believe
it was ever above 2:1, if memory now serves me correct.

The antenna was ok. However, a 1/2 monopole with a gamma feed is what I
finally settled on and still run today. Benefit is that this antenna
requires a minimal counterpoise for excellent performance and radiation
pattern and ease of construction.

Regards,
JS