My New Pixel Loop

[mstephens741]

I finally got going with my new Pixel. It arrived last week, but I had not been able to unwrap it until the weekend.

It arrived beautifully packed in a huge pizza box and was well protected with perfectly formed foam cushions. It is beautifully made with very high quality parts and careful assembly. It is "Made in America."

The instructions are foolproof and very well written. The unit is fully assembled and just needs a mount. I wanted something that was easy for me to experiment with placement and orientation. I decided on a short table as a base, and I built a sturdy 2 x 4 mount that I bolted to the table. See photo.

I ran the coax into the shack, plugged in the preamp, and connected to my Excalibur. All worked easily and flawlessly. Of course, the question is: does it work better than my DX Engineering whip? I don't know yet. I have only had a few hours of playing with it, and I haven't devised a test yet. I know it works! And my intuition by listening for a couple hours is that it is certainly no worse than the DX.

Right now my wife is laid up with a broken leg, so I can use her to go turn the antenna. Next week, she'll be hoble-worthy and I can employ her in rotator duty.

I suspect I'll figure out a test of some kind in the next couple days and I will report back. Right now, I can say it is beautiful, and works very well.

 

[Rt169Radio]

I must say it does look interesting.

 

[SCPD]

Of course, the question is: does it work better than my DX Engineering whip? I don't know yet. I have only had a few hours of playing with it, and I haven't devised a test yet. I know it works! And my intuition by listening for a couple hours is that it is certainly no worse than the DX.

Congrats!

Yes, it should work much better than the whip. Just note that for its ideal performance you need to get it away from the house. It's hard to believe, but it really is amazing how just 10 feet can make a measurable difference in signal quality.

It's hard to tell from your picture but try and locate it to an open area -- at least 30ft from any structures or metal objects (shed, etc.)

 

[Token]

I finally got going with my new Pixel. It arrived last week, but I had not been able to unwrap it until the weekend.

<<<<snip>>>>

I ran the coax into the shack, plugged in the preamp, and connected to my Excalibur. All worked easily and flawlessly. Of course, the question is: does it work better than my DX Engineering whip? I don't know yet. I have only had a few hours of playing with it, and I haven't devised a test yet. I know it works! And my intuition by listening for a couple hours is that it is certainly no worse than the DX.

<<<<snip>>>>

I suspect I'll figure out a test of some kind in the next couple days and I will report back. Right now, I can say it is beautiful, and works very well.

Keep in mind when you think about this testing to not just worry about which antenna yields the “strongest” signal on the S meter, but rather look at which yields the better signal to noise ratio (SNR). In its most simple form this SNR can be looked at as how much more understandable the received signal is, and a crude measurement can be taken by comparing the peak of the signal to the noise floor outside the signal occupied bandwidth. If you are not actively turning the loop to null noise sources you will likely not yield the full benefits of the loop, however even if you have to use the loop in a fixed position (no rotation) you can probably figure out one orientation that reduces more noise than others.

It is quite possible the whip will result in “stronger” stations on the S meter, but it is likely that the loop will, under most conditions, yield the same or better SNR. I would be surprised if the whip ever yielded the better SNR and if that does happen reverse the locations of the two antennas and see if the results are location specific.

In theory, and in pretty much all of my past experience, a loop, particularly amplified as the Pixel is, has the potential advantage over an active whip, as the loop (all other things being equal) should almost never have a noise disadvantage and has the ability to null some noise sources. It is up to the user to exercise that advantage.

T!

 

[SCPD]

It is quite possible the whip will result in &#8220;stronger&#8221; stations on the S meter, but it is likely that the loop will, under most conditions, yield the same or better SNR. I would be surprised if the whip ever yielded the better SNR and if that does happen reverse the locations of the two antennas and see if the results are location specific.

Perhaps Token can help with the Winradio software here, but the Perseus SDR application has a nice feature in that you can create reference points inside the waterfall. It will give you measurements of the signal, etc.

So to measure SNR, you would just set a reference point on a known signal (say an AM broadcast station) and then find an empty (clean) no-signal area near that station and set a point there. Subtracting these two points will give you the SNR.

So you're measuring a signal and subtracting it against your noise floor.

When comparing antennas just be sure to use the same stations/frequencies or you get wonky numbers.

A couple of points: be sure to use the same mode (AM) and same bandwidth for each test.

I'm not sure if the Winradio software has a similar feature but it can provide interesting results.

I don't have the specific numbers handy but I tested my Wellbrook 1530S+ loop against my big HF vertical antenna -- it's tuned for 40m, 20m and 10m. The signals 'sounded' better on the vertical but the SNR was about the same -- since the noise floor was higher.

The only time it was better on the vertical was when I measured 10m (28 Mhz) -- and it wasn't by much.

This isn't too shabby considering the loop is a ~3ft hula-hoop weighing 1.5 pounds versus a 30ft tall lump of metal that weighs about 50 lbs.

For that reason, I can highly recommend a loop antenna.

 

[BDM123]

I agree and for the reasons already mentioned. I have the Pixel loop, and like any loop get it away from large metal objects as best you can. Also get it on a rotor when you can as I can testify how much that can help at times in the low bands with unwanted local noise. I discovered last fall how much my fold-up 20' wide metal garage door had on it. I had it mounted about 9' off the ground next to the front side of the garage. I noticed some BCB stations would not null or null very little. I then noticed over several weeks that many of these same stations I could suddenly get close to a 30/db null, depending. Depending on which direction the stations were in. Boggled my mind and it never dawned on me initially, that the damn garage door was the culprit skewing the loops pattern.

When up, the garage door was about 3' away. I then moved the loop back farther and to the other side of the garage (to avoid the chain link fence only 5' away also), and higher up another 4'. Now it makes no difference where the garage door is, up down sideways backwards, no effect on the loops pattern regardless of how I have it pointed. Lesson learned! I felt stupid and should have noticed the possible issues but it simply never dawned on me and only effected it certain directions to boot (north/south). So get her up about 8-10' away from all offending metal objects/antennas as best you can.

As for comparisons, I only have dipoles longwire and verticals (non amplified) antennas. I live north of Detroit in an urban environment on a 165'x65' lot. Surprisingly I'm lucky. I do not suffer the noise issues that many others do, nut I have a few. One thing I can say, many of the receptions from 60/kHz through 5/MHz I've made, would have never happened or would have been plagued by ambient noise (man made or otherwise) without that loop. I have a few home brewed loops also and love them. For me it's all about sig to noise vs signal strength.