DXEngineering RF-PRO-1B Initial Review - Rob Fissel, K2RWF

Published on Mar 24, 2016

Rob Fissel, K2RWF shares his testing of the DX Engineering RF-PRO-1B Active Magnetic Receive Loop Antenna.

 

Rob, it's nice to see the background noise drop with the loop, but you could switch in an attenuator and it would do about the same. Could we listen to some actual received signals to see if they are more readable with the loop? I tried to watch some of the signals on the waterfall as you switched, but it's a little hard to tell. Anyway, it looks like it might make an improvement. Thanks for the test.

 

Hi Rob,

Nice review and well done, thanks. Most of my research on recv only loops shows the Wellbrook to be better in most if not all respects. I was wondering if you have ever used the Wellbrook and if so how you feel it might compare.

 

Well he make a nice demo on noise or signal level reduction with the loop, but he never demonstrate that a received signal has a better Signal vs Noise (S/N) ratio using the loop. Perhaps the loop simply do not hear the spectrum as well as the dipole.

 

What would have been more interesting to me is if you tuned in a very weak station, then switched antennas.

 

As Rob's video title indicated, it's the initial review. I imagine that he'll have another review when he gets situated. I'm hopeful.

 

The main advantages of an amplified loop are two:
- Amplified signal for radios that have less sensitivity, like consumer radios, or where adequate antenna type or size is not available, such as for low bands.
-The ability to rotate the antenna and steer the null to block interfering stations or noise.

There are no special properties associated with the 'magnetic" function.

 

There is indeed a special property associated with the magnetic function and it is huge. The majority of man-made noise is propagated by the electrical portion of an electro-magnetic radio wave. Utilizing a magnetic loop eliminates a significant amount of noise.

Also, my transceiver has a lot of sensitivity and I use the DX Engineering RF Pro 1B to significantly reduce noise levels and achieve improved SNR below 80M. This is in comparison to my Inverted L, which now only sees transmit duty on 160M. The magnetic loop really "opens" up 160M so you can hear and enjoy the top band!

 

I had a PRO-1B magnetic loop, and the "magnetic" function was awesome. A radio wave is made up of an electrical wave and a magnetic wave. Our receivers typically receive the electrical wave, so atmospheric QRN can be a huge problem at times. Since the PRO-1B attenuates the electrical wave, and amplifies the magnetic wave, QRN is significantly reduced with the PRO-1B. If you have heavy QRN from a nearby thunderstorm, the PRO-1B would be a major asset. The PRO-1B was designed by the USAF for EMP detection, so it was designed to receive magnetic waves.
73's, Jim, WA4YBC

 

Does anyone remember the EFH antenna claims from about 15 years ago?

Claiming to be able to separate E and M waves is a sure sign of hokum. You can't cheat physics.

BTW, I have a Pro-1B (from Pixel Technologies) and live in a townhouse. Indoors, it is just as noisy as my other antennas. If it could truly reject noise why would this be?

 

Tom, W8JI discusses myths and truths of small receiving loops, and how they don't filter or reject noise.

http://www.w8ji.com/magnetic_receiving_loops.htm

 

Well this is quite the surprise. I had no idea my video was shared here and was surprised to see my callsign at the top of Ham Headlines when checking in to QRZ this morning. Thanks for the share, Melanie!

Over the weekend, I raised the antenna up on a fiberglass mast, and added a TV rotor to the mix. This has made a noticeable difference. On to the questions...

W5DHM - Your comment is noted. I'll be sure to add actual signal reception using different antennas in the upcoming revisited review video.

KZ5R - Nope, never had a Wellbrook, for a few reasons. It's more expensive, and comes from our fellow hams across the pond. I've enjoyed DXEngineering's tremendous customer service and value, which is why I went with the Pro-1B.

HK6G - I will address S/N ratios in the upcoming revisited review video.

KF4HR - I'll do some weak station comparisons as well.

KB4QAA/AK9S/WA4YBC - Indeed, the key advantage here is the loop's capability to reject the groundwave E field of an EMF wave. Especially after adding a rotor into the mix, it's amazing the local QRM (switching power supplies, plasma TV's, etc). that I can knock out.

This antenna is a slam dunk for those who are HOA or apartment restricted. This thing will always beat out indoor or attic dipoles, etc. It will almost always outperform noisy verticals. Anyone with major locally generated QRM issues will also greatly benefit, especially if there is the ability to remotely rotate the antenna and take advantage of its 30dB nulls.

Once you start getting into stations with better, outdoor antennas, the Pro-1B becomes less of a slam dunk, but rather a solid compliment to an antenna farm. There are many instances where my 80 meter loop will out-perform or out-hear the loop on 80/40/30 meters. Rarely does the Pro-1B outperform on the higher bands where I have a beam on 20/15/10. There have been plenty of occasions however where the Pro-1B was used to null out neighborhood QRM on the low bands where something like a switch mode PS or plasma TV was causing issues on the fixed delta loop.

I suppose I had some expectations, especially after reading eHam reviews, that this thing would be a silver bullet for me on the low bands. I suspect that if I was working off of dipoles for 80 and 40, this would likely be the case. But man, I really love that 80 meter delta loop. Quiet (although not as quiet as the Pro-1B), and resonant on 80/40/20. All of this being said, the Pro-1B has proven to be very valuable after having the time to examine it's strengths, and how I can integrated it into my antenna solutions.

 

If mine wasn't working as advertised, I would have returned it. Works great against plasma TV and power line interference and even QRM'ers. The low bands, 160, 80 40 and 30 M seem to benefit the most from the directionality. In addition it does double duty as a broad banded receive only antenna for diversity receive for those who don't have room for a large, second antenna. I like the way on the upper bands how it can sometimes pick up a signal coming in from a lower angle than the inverted L can hear. Oh and by the way, it needs to be out in the clear away from other metal objects and really isn't recommended for indoor use. My yard is only 30 feet deep and it works great at the very back.

 

I have two active loops, one Wellbrook 1530 and one based on LZ1AQ amplifier and uses 4x1x1 m squares.
My dream was to have a significant improvement of s/n especially on 160 and 80 meters. Sadly, I cannot see any noticable difference to my L-antenna. Sometimes it may perform better on 80, and work clearly better on 40 meters vs an inverted vee at 12 meter.

It seems my electrosmog is evenly distributed and I do not gain anything by nulling. I am looking into remote RX.... 160 meter is next to useless as it is now

 

This is the main use I have found for mine. It does work well, and I enjoy playing with it.

I found that it offers rather little benefit indoors, but I think it would be very useful for someone in a noisy urban setting with a small back yard.