I recently obtained this fantastic new loop amp from WellBrook. This is their NEW one - the ALA100LN-M.
The unit comes with an Amp module (has 2 x 4mm banana style connectors), and a PSU for 12VDC powering from the shack.
Initial tests have show this to have noticeable gain over the LA5030 I have on indoor tests in the quietest inside area of my QTH. I used a 4.5m Hexagonal loop using 12 ga. Flex-Weave wire, 12 ga. spade lugs for connection and fiberglass-epoxy 10mm rods for spreaders.
I see at least 10-15dB higher signals on average for both MW and SW DX so far, and the antenna shows quieter performance in the same spot as tests with the indoor LA5030 loop. Strong signal tests using my CommRadio CR-1a SDR receiver so far shows that even MW strong 50kW boomers can be heard at S9+50dB with an inline 15dB attenuator, yet I can heard DX on adjacent channels (+/- 10 kHz) fairly well 80% of the time. No IMD seen in the AM BCB, or on low HF bands (160m/80m, etc.), nor on the lower SW Bands (120m/90m/60m/49m, etc.). NDB reception is VERY good, with locals not interfering when using a LP filter (the CR-1a needs this since it is designed for 0.5MHz and up, LW is an experimental area for that radio).
Typical hard-to-get stations indoors here in Winnipeg, MB, such as AIR on 9445kHz, or Voice of Korea on 9435kHz, come in very readable, even better than my outdoor 57' sloper I use for HF communication. Using the LA5030, I get barely S7-S8 (and minimal copy over local noise) recently on the two above, with the ALA100LN coming in peaking over S9 and usually S9+10dB with full copy!
I plan to do more testing over the holidays since I just got this, and want to mount it outside for further evaluation. So far, this is a winner!
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Here's some info I got on this new unit from Andy at Wellbrook:
- The new gain spec. is a power gain of 26dB. The lower gain belongs to the older version. I will take a look at the website to make sure its up to date. The new ALA100LN is basically the same as the new FLX1530LN and ALA1530LN models as well.
- The measured Zin is approx. 28 Ohms at 1MHz raising to approx.. 50 Ohms at 30MHz. The loop circumference shouldn’t exceed 7m for HF, but can be made larger for LF.
- Providing that loop circumference doesn’t exceed 0.2 Lambda the pattern will not change i.e. it will still have 2 nulls. The best near field E –field rejection is when the circumference is less 0.1 Lambda. The loop is connected to a transformer with a center tap to ground to ensure max. common mode rejection i.e. E-field.
- With a 4m loop the Antenna Factor will tend to be flat. This is because the loss due to the loops series inductance is compensated by the increase in radiation resistance with a raising freq. The JFET design ensures a very low noise floor e.g. at 2MHz the ALA100LN would have a 16dB lower noise floor compared to the W6LVP using the same loop size. Also the IMD performance is exceptional and so is the signal handling with a 1dB comp. point of +25dBm.
- The loop will be okay with Li-ion and lead acid gel batteries; the voltage should not exceed 14V. I would recommend a 500mA slow-blow fuse when using high current batteries.
ALA100LN-M: Noise and Gain Figures; A. Ikin
Noise Figures for loops (NF, dB, measured)
Freq. (MHz): 0.2/0.5/1.0/2.0/3.0/4.0/5.0/6.0/7.0/8.0
ALA1530LN/P: NF (dB)
2.12/1.45/0.80/0.51/0.33/0.27/0.21/0.21/0.21/0.21
ALA1530: NF (dB)
5.00/4.00/1.45/1.00/1.00/1.00/1.00/1.00/1.00/1.00
ALA100LN (9uH loop): NF (dB)
1.76/1.20/0.79/0.51/0.33/0.27/0.27/0.27/0.33/0.33
W6LVP Loop: NF (dB)
>8.0/>8.0/8.0/7.0/7.0/5.5/4.7/4.0/3.0/3.0
M0AYF Modified: NF (dB) - (n= not meas.)
>10/>10/10/4.0/2.0/2.0/n/1.0/n/n/
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**UPDATE: Dec 29, 2019...
I deployed an outdoor version of my Hexagonal loop made of Davis Flex Weave, 484cm in perimeter. Hung in an outdoor wooden Gazebo for now, and affixed to the gazebo rafters and beams with Bungee cord to avoid weather-cocking during windy conditions.
This is the same loop amplifier, BTW, as the ALA1530LN has on it. Andrew Ikin's latest has VERY good gain across its passband. To be honest, be prepared on the lower bands for some serious signal if you make a Loop like I did bigger than 4m perimeter! MW signals are VERY strong - I have 3x50kW boomers within 20-30kmm of my location and they peg the needle on my R75. No distortion, but "insane" gain on this loop!
You need a good communications-grade receiver or good SDR setup to handle the sheer strength of some of this signals. Using ~12Vdc, this runs very well - max V is 15V, so try to stay below 14V when running it. It can run nicely on Lithium 3S (3-cell) 12.6V power packs and holds well to about 10.8V before starting to lose some of the strong signal handling performance. A Lead-Acid cell would be near-ideal if you plan to run batteries.
I have this antenna currently about 1m off the ground, and oriented about 110-290 degrees azimuth (plane of loop). I routinely get both transpolar Asian, European and African TXs on SW, and also back-of-beam and long-path signals now from all over the place. Performance on the lower bands is superb; a 250W station in Guatemala was picked up (R. Veridad) with decent copy on 4055 kHz two nights ago.
On MW, I can get stations pretty much from coast to coast - actually there are so many, in the spring, I will be mounting this on a rotator setup as it will allow better sifting of signals. I recommend doing this, if possible, as there is a lot of gain on this amp!
LW NDBs abound, and 171kHz MEDI1 came in a week ago in the early evening - not very solid, some fading, but there. Definitely French (used my Clr-DSP unit) and solid carrier found by verifying using heterodyning... 171 kHz for sure. I am in the middle of the continent (Manitoba Canada), so some of the DX on LW and SW was very challenging until I got this unit! Despite the strong signals, this amp handles these well, and testing with 3 different rigs, I found any issues are due to the radio and NOT the amp. SO it handles IMD exceptionally well!
I highly recommend the ALA100LN-M, if you like to experiment, want good low band DX performance, and all round solid SW and HAM band reception. Again, I highly recommend rotation for this loop if you have the option, but even setting fixed as I have for the winter, there are no shortages of signals hitting me!
VERY HIGHLY Recommended!
73 de Darren VE4VE |