Topband: Inverted L improvement question

[David Olean]

Hello Wes,

     I tried 160 back in the early 70's when my brother was active from 
CO and we skedded on weekends. I used a long wire about 650 ft long for 
both TX and RX.  Working Europe was special with that setup.  I had a 
75A4 RX and a t-368 RF deck with 1000 volts on the 4-400 to net me 80 
watts output! LORAN was a big problem then. Things were dormant here on 
160 for years until recently when I resurrected the long wire. It stunk, 
so I put up an inverted VEE with the apex at 80 ft and the ends at about 
25 or 30 ft. I worked about 90 countries with that setup but I had to 
work at it. I did nab VK, ZL, UA0 and JA with that antenna but it was a 
struggle. In all my time on 160 I was never spotted on DX Summit.  I 
think I had the vee up for two winters and I am sure, I could easily 
work 100 countries with it if I were more active. Still I was at the 
bottom of any pileup.

So I determined that my inverted VEE was not so hot and I desired 
something better.  I ripped apart an old Rohn 25 80 ft tower removing 
all the VHF feedlines etc and loaded it as a gamma matched vertical for 
160 with top loading. I remember trying to tune it up during CQ WW CW 
and I had the SWR at about 3:1 as it got dark.  I had a BC band variable 
across it for tuning, and when I listened, I heard HK2NA way over S9. I 
figured the cap might withstand about ten or fifteen watts, so called 
him with low power in a pileup and he came right back! Instantly I knew 
that the vertical was the way to go.  The next day, I got the VSWR flat 
at 1810 and I was off to the races! I started to see that I was being 
spotted on DX Summit quite often. I have a quiet location with night 
time noise on the vertical at about -113 dBm typically.  I could tell I 
needed better hearing, so made a beverage, but the wire went rather 
close to one of my guy anchors and I did not think that the beverage was 
working all that well. I remember asking about it as I did not detect 
any huge drop in noise and the S/N ratio was not much better than with 
the vertical.

I discovered the guy anchor problem and its solution while driving down 
the hill from my VHF shack on the top of my little hilltop. I have a 130 
ft Rohn 45 up there for 144 MHz and a guy anchor is set right next to my 
woods road.  As I drove by it in my truck, I had the AM radio on and 
tuned to WABC in NYC a few hundred miles away. This was at noontime and 
I did not realize the radio was even turned on, but when driving by the 
guy anchor, WABC peaked up out of the noise and was good copy on the car 
radio. The proverbial lightbulb went on in my brain as I figured that 
all the noise from my tower was getting into that beverage wire that ran 
right past the guy wire. I left that beverage in place, then made an 
exact duplicate to it but located it about 400 ft away from my tower. I 
could switch between the two antennas. What a difference! Not only was 
the new wire very quiet at better than -130 dBm, but the signals from EU 
were about 5 dB better on it on an absolute basis. In short, the S/N 
ratio difference was earth shaking!  I ripped out the old beverage and 
have been having fun ever since.

Bottom line is that an active array,  a beverage, or other directional 
array is the best way to hear things no matter how quiet your QTH is.  
See the following article by K9LA:

https://k9la.us/May16_Notes_on_Low-Noise_Receive_Antennas.pdf

I have been playing with about seven beverages and my worst one 
typically is the SW wire. I see a -120 dBm noise level on my P3 at the 
narrowest span during evening hours after sunset. I had to invest in a 
BC band filter to get rid of strong BC stations as well as install 
ferrites on everything here to make the beverages behave. All have 
contributed to better receiving.


Dave K1WHS


On 12/22/2018 8:20 PM, Mike Waters wrote:
> Hi Wes,
>
> Once you try a Beverage, you'll realize that those antennas weren't hearing
> the weak ones that called you. ;-) See
> http://www.w0btu.com/Beverage_antennas.html.
>
> 73, Mike
> www.w0btu.com
>
> On Sat, Dec 22, 2018, 8:05 AM Wes Stewart <wes_n7ws at triconet.org> wrote:
>
>> Although licensed for 60 years I'm a relative newby on topband.  (I did
>> work VE7
>> in 1959 but that's another story).  I decided to semi-seriously take up
>> the band
>> to acquire my 9th DXCC band award.
>>
>> As I've described before, pardon the redundancy, I worked my first 70
>> entities
>> using an inverted-vee dipole with the apex at about 45 feet and the ends
>> down
>> around six feet.  Of course conventional wisdom says that this couldn't
>> possibly
>> work for anything but local contacts.  A year ago, I replaced the dipole
>> with an
>> inverted-L, 55 feet vertical, the rest horizontal, over a skimpy radial
>> field of
>> about (so far) 20 insulated radials each 55 feet long laying on the desert
>> dirt.  I both transmit and receive on this antenna, as I did the dipole
>> before
>> it.  I've since worked 40+ stations, completing DXCC plus a few.
>>
>> Perhaps I'm blessed with a relatively quiet location, although unlike some
>> I'm
>> not miles from civilization, but not in a subdivision either.  I have made
>> zero
>> effort to silence noise sources in my house, but do work with the local
>> co-op
>> power utility to silence obvious noise sources. (Their sleuth is a ham)
>> Although I'm considering an RX-only antenna, and it might be eyeopening,
>> I'm not
>> yet convinced of that.  Anything I would use on RX would probably have a
>> broad
>> peak and get its noise rejection from the rear.
>>
>> Examining where most of the unworked DX is from here (EU, ME and central
>> AS) the
>> paths are mostly over the (noisy) continental land mass of NA (and the
>> polar
>> region) at my SS or early evening.  The null of any RX antenna pointing at
>> these
>> areas would be looking at the sunlit Pacific Ocean.  At my SR, the
>> converse
>> would be true.
>>
>> So all things considered, using only 500W (10dB too few according to one
>> of my
>> friends), I already hear as well as I'm heard.  My bigger obstacle is QRM
>> from
>> the east. Nevertheless, I'm willing to try an RX antenna, if I can be
>> convinced
>> it will be of benefit, so I'm open to suggestions.
>>
>> Wes   N7WS
>>
>>
>>
>>
>> On 12/19/2018 7:13 AM, Rob Atkinson wrote:
>>> If your inverted L is any good at all it will suck as a receiving
>>> antenna.  This is one of the key things to accept about medium wave
>>> but many casual 160 m. operators can't wrap their heads around it.   A
>>> flame throwing tx antenna will probably have a completely unacceptable
>>> noise level on receive.  Tx/rx reciprocity works on HF but not as well
>>> on medum wave.   Separate rx antenna(s) are mandatory.    A
>>> significant irritant on 160 are the operators with poor antennas that
>>> hear great, therefore they expect to be heard equally well, and can't
>>> be made to believe they are piss weak when they transmit.
>>>
>>> Rob
>>> K5UJ
>>
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