[Elecraft] K3 & S9 43' Vertical

[Lew Phelps K6LMP]

I am in the process of installing a 43-foot vertical at my QTH (made by DX Engineering, but should be the same for purposes of this discussion).

I have modeled this antenna on all bands assuming a 4:1 Unun at the base of the antenna, a 75 foot run of 9913 coax, and a home-brew L antenna at the transmitter. TLW (Transmission Line for Windows) calculates the tuner settings needed for all bands, and also calculates the loss in the tuner (low) and the line.  With severe SWR mismatches on the lower bands, you get 75-85% of the transmitter power into the antenna. That is, worst case, if you have 100 watts output from your rig, you get 2 watt loss in the tuner and 22 watts loss in the transmission line, giving 76 watts out.  this is theoretical calculation, of course, but I think it gives a good indication of the order of magnitude of the line losses. The longer the line, the greater the line loss, of course. One might be able to improve on that with the switchable tuner described by AD5X; I'm going to have to look into that!

My UNUN is home-brewed based on a design from Sevick's book on Balun and Unun construction.  I can provide details offline to anyone interested. material cost is about $40 for toroids and Thermalize wire, and it's capable of handling full legal limit, although at the moment I'm running my K3 barefoot 10 watts.

The tuner is a home-brew switchable configuration L tuner. On all bands, the "best" configuration is a low pass filter with the shunt capacitor on the input (transmitter) side. Inductance and capacitance requirements are well within the limits of the tuner on every band.

I'm all done except laying the radials. I'll report back as soon as I'm on the air, after having conducted some A/B tests on the air alternating between the new vertical and my existing HF antenna, a 40 meter horizontal loop.  I expect significantly better DX performance with the vertical, since it puts most of the radiated energy out toward the horizon rather than almost straight up.

73,

Lew K6LMP




On Mar 22, 2011, at 9:51 AM, Julius Fazekas n2wn wrote:

> Hi Tom,
> 
> Check out Phil's, AD5X, site: http://www.ad5x.com/articles.htm
> 
> He has written a number of articles related to your questions. Good
> information with plenty of "how to" ideas with locally found materials.
> 
> Elecraft's Balun kit is also capable of 1:4 unun and will easily work with
> any 100 watt rig.
> 
> QST has had several items related to the ubiquitous 43' verticals that are
> all the rage now. I see at least one person has mentioned radials, which are
> a must have to effectively use this antenna on 80-30.
> 
> The K3's ATU is very effective, but keep in mind that you will be matching
> the feedline and antenna as a unit, versus matching just the antenna. The K3
> will most likely find a match most of the time, but you still could be
> seriously mismatched at the antenna. It may work, it just won't work well.
> 
> GL es 73,
> Julius
> 
> -----
> Julius Fazekas
> N2WN
> 
> Tennessee Contest Group
> http://www.k4ro.net/tcg/index.html
> 
> Tennessee QSO Party
> http://www.tnqp.org/
> 
> Elecraft K2        #4455
> Elecraft K3/100 #366
> Elecraft K3/100 #1875
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-S9-43-Vertical-tp6193993p6197137.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html