[CQ-Contest] SSB & CW On Same Band

[Jim Brown]

On Sun,3/19/2017 7:25 PM, Steve Lott wrote:
> Ed and Jim
>
>
>
> I am also building an 80m Rhombic on the back 24 acres of property
> progress is slow, it won't be high but hopefully it will be an asset in
> ARRL SS from North Texas

If you're on the west coast or KH6/KL7, a gain antenna pointed east is 
an asset for SS. If you're in the middle of the country, it's a 
liability, and a dipole is better.

>   at least one person has told me the Rhombic is a waste of my time and I should just use Inverted Vee's at 60 feet of height

I agree that a Rhombic is a pretty limited antenna on 80M. Instead, I 
would consider a flat dipole as high as you can possibly get it, 
spending the bucks needed for those poles for tall towers instead. Take 
a look at   http://k9yc.com/AntennaPlanning.pdf  which shows the value 
in dB of height of horizontal antennas. My 80M antennas are dipoles at 
140 ft (I have redwoods), and the one broadside to the NE has a 
reflector giving it gain to EU and the east coast. My ground 
conductivity is pretty bad, so the only band where verticals outperform 
dipoles is 160M -- even at 140 ft, a horizontal antenna is low on 160. 
:)  I had one for a while, and with a LOT of A/B comparisons the 
vertical nearly always beat it.

> I have the Telephones poles installed now just need to find the time to get
> the wire strung tune it and run a thousand feet of ladder line to the back 24 acre lot from the Shack
>
> I currently have One Four Square installed for 40m
> it is on The Eastern side of the property and Northern Half
>
> I plan on the 80m Four square Due west of the 40m array
> with a separation of 600 feet

As that Antenna Planning link clearly shows, the gain of a vertically 
polarized antenna is strongly dependent on the quality of the soil, both 
under the antenna and in the far field. A 4-square will have significant 
gain over a single vertical installed at the same spot, but if you have 
poor ground conductivity, a high dipole may outperform it, because 
horizontal antennas are NOT affected by ground quality, they are 
affected only by their height and the terrain.

> The only other Current antenna in use for Transmit is an Eight element
> Sterba Curtain Array
> hung with broadsides to NE and SW hung between two,  not quite high enough
> telephone poles.
> Bottom edge of the array would touch the ground but is propped up on
> insulated posts
>
> It seems to work rather well on 20m, but right now I have little to compare
> it with

Have you modeled it?  I suspect that those very low elements are 
worm-warmers, burning the part of transmitter power fed to them.

> Ed,
>
> You mention 1/2 inch cable TV hardline and I have a spool of that but have
> not seriously planned for it's use
> did you do anything to reduce the impedance mismatch from 52 ohm line
> I know it's not a lot of mis match, so maybe you just don't worry about it ?

I use that stuff to feed monobanders for 20 and 15. The hard line is 
carefully cut to multiples of a half wave, which approximately makes 
them disappear from a mismatch point of view (the approximation is their 
loss).  See k9yc.com/Coax-Stubs.pdf

I further optimize it by measuring the feedpoint Z of each antenna, 
importing that in SimSmith, and tweaking the length of the 50 ohm 
section between the antenna and the 75 ohm section to optimize the match 
over the band. In at least one of those antennas, I used a stub in the 
50 ohm section. See http://k9yc.com/PacificonSmithChart.pdf for the 
general technique.

You'll need a good way to measure antenna impedance. I strongly 
recommend the VNWA 3e, designed by EE prof DG8SAQ, built and sold by SDR 
Kits in the UK. Excellent bang for the buck, especially with Britain's 
Brexit mess, far superior to other products from US mfrs.

http://sdr-kits.net/VNWA3_Description.html

73, Jim K9YC