Many thanks to SWLing Post contributor and noted DXer, Guy Atkins, for the following guest post:
Wellbrook 1530LNPro vs ALA1530S+ Imperium Loop Antennas
This past weekend I found some interesting results from medium wave DXing with both models of Wellbrook Imperium loop antennas at the “fabled” Rockworks cliffs near Manzanita, Oregon USA. This location has become popular the last few years with Oregon, Washington, and British Columbia DXers due to the signal enhancement at this narrow strip of land approx. 450 feet above the Pacific ocean. The main benefit seems to be splatter reduction of “pest” stations due to the signal blockage of the rock walls blasted into the cliffs for the coastal highway 101. However, a boost of signals around local sunrise is also beneficial, and is a common occurrence near salt water beaches.
Here is a Google Maps Street View of this beautiful “wide spot in the road” along the cliffs.
Because of the limited space along this scenic coastal highway, all antennas used for DXing need to be both compact and temporary. Wellbrook loops supported on pro-audio speaker stands are a great way to go, and can easily be set up in the pre-dawn darkness.
This is a comparison file of weak signal reception with the two models of Wellbrook Communications “Imperium” series loop antennas: the ALA1530LN “Pro” Imperium and the ALA1530S+ Imperium.
Both models of compact, 1-meter dia. active loops are excellent for reception from longwave & medium wave upwards. However, the ALA1530LN “Pro” excels at LW & MW with its low overall noise level and 9dB higher gain, engineered by Wellbrook for improved signal-to-noise ratio (S/N) of up to 10 dB. S/N on the HF bands is reportedly better also.
On the weekend of October 24th, 2015 I was DXing at the “Rockworks” cliffs on the Oregon coast near Manzanita, OR. Both of these Imperium series antennas were in use and I was recording the medium wave band with an Elad FDM-S2 SDR receiver. Both antennas were fed with identical 25 ft. lengths of RG-58 coaxial cable.
The demonstration in this video begins with 10 seconds using the ALA1530LN Pro Imperium loop, alternating with 10 seconds with the ALA1530S+ Imperium loop.
The first signal tuned is aviation voice beacon “SQM” from Level Island, Alaska on 529 kHz (400 watts). The signal is weak, but audible as it rises above the noise floor. The reception improvement with the ALA1530LN Pro is evident.
Half way through the recording the frequency is switched to 1710 kHz, where an unidentified station (possibly a MW pirate) is audible playing the 1967 Zombies tune “Time of the Season”. Again, the clip starts with 10 seconds with the ALA1530LN Pro alternating with 10 seconds of the ALA1530S+ Imperium.
Each antenna is a worthy, compact loop for DXing, but for chasing the weakest signals with the best readability I think the ALA1530LN Pro shows its advantages.
Many thanks, Guy, for sharing your loop research!
What I love about your portable SDR set-up, is that you can go to the cliff side, set up your antennas and equipment, record the spectrum on your SDR, then go back home to analyze and listen to what you captured. It takes some of the pressure off while you’re on-site.
This year at the Dayton Hamvention, I purchased the Pixel Technologies RF PRO-1B mag loop antenna. I used it (for the first time) at the PARI DXpedition. We were all impressed with its performance. I would love to compare it with the ALA1530LN Pro at some point in the future.