Topband: Some experiments with a short beverage, not succeeding very well

[Artek Manuals]

Mark

Tell us more about the transformer? My own experience is that core 
material and impedance matching at the frequency of interest often pays off.

I have a 200' BOG (N-S) and a 460ft� x 6ft Beverage (E-W) . Both 
antennas work very well for what they are comparing them to what I hear 
on the Xmit antenna. In the "development " phase I found that measuring 
the actual feedpoint impedance and then making sure that the impedance 
matching� ratios are "close" resulted� in very predictable and 
repeatable results. I dont have my notes handy , and both my antennas 
are essentially "Reversible" coax antennas. One transformer turned out 
to be 3:1 and the other 5:1. I get performance on 160-40, noticeable 
poorer performance 30M� and� very poor signal signal 20M and above. I 
attribute this to the matching transformer design which favors the lower 
frequencies.

Everything for the moment was done using� cheap RG-6. But I will be 
replacing all of that with a RG-58 construction in the fall.

Dave
NR1DX

On 6/30/2020 2:56 PM, Mark Lunday wrote:
> "Beverages just want to work" is what I have heard.
>
> Not having much luck with that here. I suspect operator/installation 
> error.
>
> I did a lot of reading and I must be doing something wrong.
>
>
>
> * 250 feet of insulated wire strung out in 030 degrees direction 
> toward EU, pretty straight, varying in height from 4 to 6 feet, 
> running through thick brush with no metal objects or artificial 
> elements along the run.
> * 9:1 transformer at feed point with ground rod
> * 300 feet of coax, mix of RG-8, MMR-400 to get to the edge of the 
> woods from the house
> * No terminating resistor
>
> On bands 160-40, the signals are very weak. I am monitoring WSPR, FT8. 
> I can hear signals on 160-40 but they are way down compared to dipoles 
> and inverted L on the same bands. Like 20-30 db down. From what I 
> read, I should NOT need an HF pre-amplifier, right?
>
> Signals on 30 and 20 seem to be better and I can copy some DX from EU 
> on FT8.
>
> I will try installing a new ground rod, the old one is 10 years old 
> and perhaps not making a good ground connection at the feedpoint. The 
> transformer is brand new, so that's not an issue. The coax has tested 
> out fine. Soil is central North Carolina clay, a bit dry at this time.
>
> I am guessing performance is poor on 160-40 because of the short 
> length and that it's bi-directional (no terminating resistor), which I 
> am seeing on 30 meters. But I did not think it would be THIS bad on 
> 160-40....
>
> Mark Lunday, WD4ELG
> Greensboro, NC FM06be
> wd4elg at arrl.net<mailto:wd4elg at arrl.net>
> http://wd4elg.blogspot.com
> SKCC #16439 FISTS #17972 QRP ARCI #16497
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector

-- 
Dave
Manuals at ArtekManuals.com
www.ArtekManuals.com


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