[Elecraft] Best Portable Antenna

[Fred Smith]

Hi Dave

Thanks for the info, Nate had emailed me yesterday about it and I was sadden
to hear of his health issues that had caused him to pull back from the
project for a while. I linked to it yesterday nice to hear from someone that
has one in use for a while.

73,
Fred/N0AZZ

-----Original Message-----
From: Dave Van Wallaghen [mailto:w8fgu at comcast.net] 
Sent: Tuesday, January 29, 2013 7:20 AM
To: Fred Smith
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Best Portable Antenna

Fred and all,

Realizing that the terms "best" and "portable" mean different things to 
different people. Here is a portable vertical that I've been playing 
with since June: http://www.n6bt.com/n6bt-Bravo7K-1.htm

This is a design from Tom Schiller, N6BT of the Force 12 era. He has an 
entire new line with his new company. This antenna is an asymmetrically 
fed vertical dipole. It supports 7 bands, 10m-40m via tuning of the 
lengths of tubing and some loading coils on certain bands. It is full 
length 10m - 20m and there is some loading for 30m & 40m. He touts 
90-99% efficiency with upper 90's for the non loaded bands and 90-95% on 
the loaded bands.

The asymmetric design allows the feedpoint to be at the bottom for ease 
of feeding and keeps the center of gravity for the antenna near the 
bottom. I ordered mine with the tri-pod base and made up 3 u-shaped 
aluminum stakes to hold the tri-pod to the ground in the yard. So far it 
has survived hurricane Sandy effects here in SE Michigan and winds over 
50mph. I did have a 60mph gust last week that finally pushed it over - 
no damage.

I regrettably have little time to operate these days, but when I'm doing 
other things in the basement I run WSPR and have done direct comparisons 
with my window line fed 140' doublet. It performs comparably in my 
opinion. It exhibits the same properties as a vertical i.e. noisier, 
lower take off angle etc. Using both antennas for diversity reception is 
really cool. It almost eliminates QSB conditions sometimes in that if 
the QSB is changing polarizations, you hear the signal move from one ear 
to the other.

There was a review of this antenna in QST last year and some suggestions 
were made by the reviewer, Ward Silver, N0AX, about mounting things more 
efficiently for changing bands etc. All of the suggestions made were 
incorporated in the version I received.

Although the price tag is around $290, I believe it is cheaper than some 
of the comparable Buddi-system configurations. Obviously, I can (and 
have) made simple wire antennas for far cheaper and perform well. It 
just takes me a lot longer sometimes to get the wire where I want it. 
The one thing I like about the Bravo 7K is that it is made from easily 
purchased parts so that you can repair it in the field if necessary. I 
found all the lengths of tubing on the DX Engineering site. All of the 
hose clamps to secure the tubing are SS hose clamps found at most 
hardware outlets.

It is portable and light, weighing in around 12 lbs or so, but not 
something you'll want for backpacking or other type of operating where 
keeping the weight down is a priority. I bought a drum hardware bag for 
mine that holds the antenna and all supporting cables, stakes, rope, 
tools etc. I made a W2DU balun for mine that is permanently mounted 
underneath the loading coil box. I found that tuning it was pretty much 
like it is laid out in their manual. I used a pipe cutter to notch my 
tubing elements so that I can easily change bands in seconds without 
remeasuring. It can be detuned fairly easily on 30 & 40m by large 
objects or different soil near the placement.

I have taken it on a couple of small trips in the last few months and I 
can set it up in less than 15 minutes and be on the air. I'm currently 
stressing it out with a Michigan winter and hoping to be impressed with 
its toughness if it still works this spring ;-)

I have no outside interest in this company, just a satisfied owner at 
this point. YMMV.

73,
Dave W8FGU



On 01/29/2013 04:36 AM, Fred Smith wrote:
> To the Group