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Author Topic: Hi to all from YV5EN  (Read 1036 times)

Offline YV5EN

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Hi to all from YV5EN
« on: December 13, 2013, 01:09:28 UTC »
Hi every one, my name is Edwin, from Caracas Venezuela, 99% CW ham radio op since 1979.
I'm very active in 40, 20, 15 and 10m.
My first callsign was YV5HUJ from 1979 to 2011, and now I'm YV5EN from January 2012 onwards.

I like chasing DX and QRPing very much, using my Elecraft KX1 and also using my very oldie Heathkit HW-8.
I would like to CU on the airwaves soon.

72 es GD DX

72 es 73, Edwin
Twitter: @YV5EN
Proud to be the First and only Ham in Venezuela to achieve QRP DXCC.
NAQCC Lifetime Memeber #4881, Straight Key Century Club #8307, Flying Pigs QRP Club #2713, Polar Bear QRP Club #299, Member of SPAR Society for the Preservation of Amateur Radio, ARRL & RCV member...

DF5WW

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Re: Hi to all from YV5EN
« Reply #1 on: December 13, 2013, 12:25:21 UTC »
Welcome here and congrats for your QRO DXCC. Habe 179 DXCC´s (all QRP) verified by LotW (mixed) but never applied the award. This one looks better as the "normal" DXCC award. Maybe i apply in the common future ;-)

Offline sm5mek

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Re: Hi to all from YV5EN
« Reply #2 on: December 14, 2013, 11:06:52 UTC »
Hi fellow QRP DXCC holder, it was nicer to get this than the big brother dxcc, it demands more effort and skill.
Congrats to it.
Best regards, 72 de SM5MEK, Jenny.

Offline AF7Fb

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Re: Hi to all from YV5EN
« Reply #3 on: January 06, 2015, 02:27:54 UTC »
Wow Edwin, you should be very proud.
I am still trying to make my first contact around here. I got an Elecraft KX3 and an end feeder antenna.  Let me know if you ever wanna talk.  73's
Alex.     
AF7FB

Offline KC8AON

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Re: Hi to all from YV5EN
« Reply #4 on: January 06, 2015, 13:05:52 UTC »
Wow Edwin, you should be very proud.
I am still trying to make my first contact around here. I got an Elecraft KX3 and an end feeder antenna.  Let me know if you ever wanna talk.  73's
Alex.     
AF7FB

Alex, Gang,

Many times I hear and see statements like yours - "still trying to make my first contact" or "I have and end fed wire antenna"  Folks, if you're gonna operate QRP, to increase your chances of making contacts you need to put up an efficient antenna as possible and get it up as high as possible.  End fed wires work, there is no doubt in my mind, but for them to work they must be setup right.  These new fangled end fed antennas with a unun or balun at the feedpoint and marketed as "all band antennas" are a gimmick to get your money.  Granted they will work when conditions are good, but they require a tuner to work properly.  There are better choices out there and you don't have to spend lots of money to have an efficient antenna.  Do yourself a favor and research the subject to find what you can fit in your available space such as a center fed dipole, off center fed dipole, or whatever.  The thing is, we QRPers are working with about a 6db handicap in the first place, so why put up a handicap antenna ?  Not trying to give anyone a hard time here, just wanting to see folks get as much fun out of their hobby as possible so they won't get discouraged !

73 all,
KC8AON

Offline WH7TT

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Re: Hi to all from YV5EN
« Reply #5 on: January 06, 2015, 18:00:05 UTC »
KC8AON,
     Very interesting. I have been researching antenna efficiency. As most know this is the percentage of radiated power/input power to the antenna. So far in my research, it seems, that dipoles give you the best results and therefore the most power radiated into the ether. Of course that is for the frequency which they are cut and for the bandwidth of that antenna.
       Do you or anyone else have any ideas or suggestion on what would be more efficient? The real battle hear on transmit is total power radiated while the battle on receive is signal to noise ratio. I have found a site and have been reading at http://www.antenna-theory.com/ that gives a lot of information on antennas but input is welcomed and desired.
Mahalo,
Edward

Offline GM0LVI

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Re: Hi to all from YV5EN
« Reply #6 on: January 06, 2015, 20:59:12 UTC »
KC8AON,
     Very interesting. I have been researching antenna efficiency. As most know this is the percentage of radiated power/input power to the antenna. So far in my research, it seems, that dipoles give you the best results and therefore the most power radiated into the ether. Of course that is for the frequency which they are cut and for the bandwidth of that antenna.
       Do you or anyone else have any ideas or suggestion on what would be more efficient? The real battle hear on transmit is total power radiated while the battle on receive is signal to noise ratio. I have found a site and have been reading at http://www.antenna-theory.com/ that gives a lot of information on antennas but input is welcomed and desired.
Mahalo,
Edward

Hi Edward,
The "best antenna" depends on the space you have, and if you are not into construction on your bank balance too!
Total power radiated isn't the complete answer although transmission line loss is an important consideration as are losses due to mismatch. The other important factor to consider is getting the radiated power going in the best direction for the station/s you want to contact.
A simple dipole can work well though the height is important, if it's too low you'll get high angle radiation which is great on the LF bands for local contacts but not great for DX. A sloping dipole will give a little gain in the direction of the slope and adding a reflector will give  little bit more gain.
The next step up the gain ladder might be a VDA or vertical dipole array and several recent expeditions have used these but usually in close proximity to the sea.
For a little bit of gain over a dipole (at optimum height) a quad loop will work well givibng about 2dB gain and does add the benefit of a considerable reduction in noise levels. Then of course if you want to go a bit further up the gain ladder you can add an additional element and you should benefit by about 7 dB over a dipole (and 2 dB over a 2 element yagi).
My first quad (photo) was a shortened quad for 17 metres. I didn't have space or height at the time for a full size one so made this when a utility pole in the garden became vacant. I based it on a design I seen for a small size 80m quad with both elements driven - hence the long stubs that also work as phasing lines. Tuning it was very hard work as I had to climb a ladder to adjust the feed point and I'd no antenna analyser then so had to go to the shack to see how it was looking.
Putting it up was good exercise - I had to carry the rotator uo the ladder, fix it and then carry up the assembled quad.
You'll note from the photo that I also grow good onions and tomatos and have a lovely xyl too!
Dave

Offline KC8AON

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Re: Hi to all from YV5EN
« Reply #7 on: January 06, 2015, 21:23:14 UTC »
KC8AON,
     Very interesting. I have been researching antenna efficiency. As most know this is the percentage of radiated power/input power to the antenna. So far in my research, it seems, that dipoles give you the best results and therefore the most power radiated into the ether. Of course that is for the frequency which they are cut and for the bandwidth of that antenna.
       Do you or anyone else have any ideas or suggestion on what would be more efficient? The real battle hear on transmit is total power radiated while the battle on receive is signal to noise ratio. I have found a site and have been reading at http://www.antenna-theory.com/ that gives a lot of information on antennas but input is welcomed and desired.
Mahalo,
Edward


The one and only way I know to increase efficiency of the antenna is to decrease system losses.  For example, a center fed half wave dipole at resonance is around 85% efficient if fed by good low loss 50 ohm coax.  But by changing the coax feedline to a very low loss balanced feedline such as 450 ohm window line, you can increase that efficiency to around 95%, but this also requires a well designed low loss balanced tuner.  The other advantage to this is that you get multiband operation with one antenna as the tuner allows operation on bands higher than the design frequency, and as you go higher in frequency, the antenna gain is higher because it is electrically longer than a half wave.  For example, a half wave 80 meter dipole is one wave length long on 40 meters but is a very high impedance on 40.  Since balanced feed line still maintains its low loss property even at a high swr, you can still get it to operate on 40 via the tuner. Also, to get maximum efficiency of any resonant antenna, make sure its as near as full size as possible.  In other words, try to avoid loading coils that shorten the antenna and add losses to the system.  With antennas, a big (full size) antenna is always better than a smaller antenna.  Take for example a resonant, coil loaded mobile antenna where the efficiency may be somewhere around 15 to 20% efficient as compared to a full size quarter wave vertical that may be around 60 or 70% efficient.  Basically, you want to assure that as much of your RF power gets into and out of the antenna as possible and things like coils, traps, ununs, and baluns can add losses to the system and ends up being wasted in the form of heat caused by resistive losses.  Baluns and ununs by the way can be very efficient in transferring RF, but only as long as they are designed and used properly such as in a well matched system.  An example of that is a well designed, dual core 4:1 current balun in an off center fed dipole where the balun will be operated in a matched (low swr) condition and show around 95 to 97% efficient transfer of RF to the antenna.  The off center fed dipole by the way is a very efficient antenna that works several bands without a tuner ! 

Good DX all !