[Amps] new amp race

Jim Brown jim at audiosystemsgroup.com
Sun May 21 15:23:12 EDT 2017


On Sun,5/21/2017 11:50 AM, Catherine James wrote:
> The next cheapest 10 db is installing a tribander at 70 ft or higher.

I don't know of any tri-banders that will give you more than about 7 dB 
over a dipole (dBd), and most are in the range of 3-5 dBd. Stack a pair 
and pick up another 3 dB, as well as diversity of vertical pattern.

 From an engineering point of view, Cathy's points are right on target. 
EVERY system is different -- engineering is the art and science of 
compromise tailored to the system in question. As she notes, nearly all 
hams are limited in what antennas we can put up, by our RX noise 
environment, and by our budget. A compromise that's great for one of us 
may be less than ideal (or even quite poor) for the next guy.

I'm lucky to have a lot of real estate and a lot of redwoods, and to 
have moderate RX noise on most bands most of the time. The trees are 
free, but the tree climbers are not. :) High band antennas are Yagis at 
120 ft and 40 ft. My low band antennas are wires as high as I can get 
them (about 140 ft) in those trees, and I've got four RX antennas. I've 
also got a pair of 87As (bought used) and a KPA500 (for 600W on 6M and 
instant-on). And I've spent a LOT of time minimizing my own 
contributions to RX noise -- there are no SMPS in my home/shack. I'm 
pushing the envelope from both directions -- legal limit power and 
optimizing both TX and RX antennas.

And as another kind of challenge, I also run QRP in DX contests. 160 
countries QRP, 319 at legal limit.

I have no respect for hams running illegal power -- I view it as 
cheating, just like Lance Armstrong and Barry Bonds.

73, Jim K9YC



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