[ADXA] RX Antennas - What's in Your Station??

Mon Jan 13 12:09:53 EST 2025

Bill, in my opinion, is absolutely right. What I originally struggled with was after I put the pennant up is I would have a much better SNR ratio, but a whole lot less signal on the s-meter. At that point I was receiving only US stations. I didn't know if the DX stations were there, and I couldn't hear them because the pennant cut too much signal, along with reducing the noise.

Fortunately, Mike KB5WBH also started leaving his receiver on overnight, and he receives much better than I when we are both running  our inverted Ls. This way I could compare the signals received at a specific time. I will say now, that this is not a completely accurate way to test, but has worked well enough to learn a few things. The first week of testing was a disaster on my part. I wasted one night by leaving the RX on my inverted L. The next few nights were wasted until  I realized that, for whatever reason, my front was the back, and the back was the front. This was completely opposite of what the drawings I used in construction had shown.  I plan to make some changes to my construction by reversing the feed point and terminating resistor, to see if the directivity stays the same or reverses. Because of this, I tested a week with the front pointed right into a metal building, and the back to Europe.

After figuring  out the best RX driection, "by accident", I moved the pennant and pointed it South East hoping to receive South America. I was not disappointed. It was then it appeared that there was a pretty deep null off the back, as compared to Mike's inv L, but for the most part was as good or sometimes better off the front. I am leaving my receiver on 160 ft8 most every night, with the pennant pointed South East. If you want to compare your antenna to the pennant, I would welcome any comments, good or bad.

I recorded a short video of what I am dealing with as far as noise. As you can see on the inverted L, my noise with no preamp is over s9 and the loop is just as bad.  In the video I switch to the pennant and you can see the difference.  I have much more to do on this project to make it user friendly such as automatic switching  from RX to the TX antenna. At 400 watts, the transformer on the pennant becomes "communication by smoke signal" in a matter of seconds, which I have already done twice. A second pennant, in another direction would also help determine if it does really help.

Here is a link to the video I made this morning.  https://youtube.com/shorts/PKY833kFbtU?si=YwE_3sKn0SBviIwV

Randy W5ZJ
________________________________
From: adxa-bounces at mailman.qth.net <adxa-bounces at mailman.qth.net> on behalf of BILL KENNAMER <k5fuv at prodigy.net>
Sent: Monday, January 13, 2025 10:00 AM
Cc: adxa at mailman.qth.net <adxa at mailman.qth.net>
Subject: Re: [ADXA] RX Antennas - What's in Your Station??

My two cents: The primary reason for using a separate receive antenna on the low bands is to cut noise and, maybe, add directivity. It should not be expected that a receive antenna will automatically provide better signal strength. It usually won't do that. The objective is to provide a better signal to noise ratio, and most will do that. If you compare the noise between the RX antenna and TX antenna, you should be able to tell a difference. Intelligibility is what makes the difference. For example, my YCCC system provides less signal strength, but makes the difference in whether I can hear the signal well enough to copy my call/his call correctly. My system uses pre-amps at each antenna, plus I pre-amp it at the receiver as well. Sometimes the signal strength is equal, mostly not, but I can tell a big increase in intelligibility, and I find that I can hear clearly things that other callers can't hear. This is especially true on 80M, where I often hear EU stations very early in contests, and am able to work them before there are any other callers at all.

You can also find big variations from night to night. Sometimes polarity, angle, and propagation levels change. So, it is best to evaluate RX antennas over a period of time. If you can see directivity, keep it, it's working.

Bill K5FUV

On Monday, January 13, 2025 at 09:37:52 AM CST, Charles Korzendorfer <korzendorferc at gmail.com> wrote:

Guys,
  So I have been struggling with a K9AY loop array for a few years.  I had it installed in my back yard for two winters, but very dissatisfied with the performance.
  This year I moved it to my front yard in an effort to get it further away from the tower.  Used it last Saturday in the NAQP, & no improvement.  I am convinced it is just to close to my tower to work properly.
  Bottom line for me is if you can hear better on your transmitting antenna, it is not working.
  Back to the drawing board for me on this project.
Chuck. KM5G

On Mon, Jan 13, 2025 at 9:02 AM <w5znjoel at gmail.com<mailto:w5znjoel at gmail.com>> wrote:

Greetings ADXA Folks,

Randy, ZJ, peaked my interest this morning about what RX antennas (with good observations on performance) and what is being used among the ADXA folks. Randy is using a Pennant, Dennis RZ is in the process of putting up a loop or Pennant, EJ and UR have Beverages. Stan GO has a YCCC-9 down in Cayman Brac and Bill FUV had a YCCC-9 at one time.

For others who have a low band RX antenna, what are you o you have???? Inquiring minds need to know!

73 Joel W5ZN

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