PALSTAR LA30 Ferrite Loopstick
The Palstar LA30 Ferrite Loopstick Antenna on left.
Prototype built in a plastic case on right.
Both shown with the MW loopstick attached.
Laying on left side of the prototype's case is the "tropical band" element.
(left Palstar photo, right N9EWO photo)
Very Important Note : The review and information you read below was done with a PROTOTYPE of the Palstar LA30 Ferrite Loopstick Antenna, and may be different when compared to actual production samples. We have NOT tested a actual production unit at time of writting (and have no plans to do so).
Up With This Thing ? / High Quality Tuning Capacitor
OK, so Im not a Medium Wave DX broadcast listener. I may tune casually around the band once in awhile and thats about it. However in mid-August of 2008 I was very fortunate to obtain a prototype of a Ferrite Loopstick Antenna from the RF engineer (Pete Gianakopoulos KE9OA) who designed it for Palstar in Ohio USA. In the spring of 2009, the model number was decided as the "Palstar LA30".
IMPORTANT: What I cover here with this prototype may not be true with any actual production sample. For two, the prototype lacks the power and attenuator buttons. No internal AA battery holder either. The PC board (at least in the tested prototype) is of a high quality glass epoxy shielded type. The numbers on the 2 boards shown in the photo below are slightly different. The RF engineer gave me an "extra" PC board with no parts on it at the same time as shown in the picture below. Im sure that other minor differences exist too ?
The large and geared tuning capacitor is used in actual production samples. The one installed in the tested prototype was smaller, however it's still larger than most caps that are used in gear today and even has ball bearings. But in either case it uses a much HIGHER quality capacitor over the current production Quantum loops, which use a tiny and much lower quality plastic transistor radio tuning cap (for example what you would find in a cheap $ 2. AM pocket radio ?).
The prototype was built in a large plastic box. Of course the production units are in a solid all metal case.
Production Palstar LA30 "7472401" PC Board w/parts (on left)
Prototype "7472400" PC Board with no parts attached (on right)
(left Palstar photo, right N9EWO photo)
Loop and FET Amplifer / How Well Does it Work ?
Very high Q and gain, approx. 20 db > area (for the prototype). Yes, very VERY SHARP tuning. Balanced loop / amplifier design using two surface mounted MMBF5486 FETs followed by a MMBR941 output transistor. However, from viewing the "on line " owners manual and schematic, production samples use a MMBT5486 output transistor (or is it a MMBT5179 ?). The on-board 10-volt regulator is a nice touch however it was not used in the prototype (bypassed) for the increased gain. I just have to remember to use a 12 volt regulated wall wart with it (no biggie). The web site and owners manual specifications list the gain as 15 db.
From what I can tell (with my limited MW loop experience) the performance / gain is excellent using the MW loop with equally excellent directivity as it's rotated. With the PROTOTYPE Tropical Band loop, the gain is the same but with less "sharp" tuning. This can be expected with the frequencies involved. Rotating it does little to null out noise/signal again with the higher frequencies. Also the tropical loop was wound on a slightly shorter ferrite rod over the MW one (remember : these are prototypes). Additionally I was told that production samples are using slightly thicker ferrite rods. In all cases the loops are wound using # 36 x 14 strand Litz type wire. Additionally, these loops do not tilt in any way and of course the Quantum ones do.
On ONE very strong MW local signal, I had to kick in some attenuation (or slightly off peak the tuning) to control some minor "receiver" overload. But this was not a real issue and the production units have a switchable 15-db-attenuator button just in case.
This prototype coverage is from 520 to 1700 KHz on the MW loop element, and from 1700 to 5500 KHz on the Tropical Loop element (actually up to 6500 > KHz with reduced performance/gain).
Prototype "Rear View"
Prototype A Winner ?? / Too Expensive
No . it probably does not work as well as a larger loop, but considering the size of this antenna, this prototype of the LA30 performed very well indeed to my ears. It does not require all kinds of room either. If production units work any differently... sorry I cannot say, untested as I type this text. Palstar does seem to have this loop a bit overpriced in my view, and the LW and Tropical Loops are even sold seperate adding to the already high cost (comes only with the MW loop).
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