RE: Re: Re: Re: Re: Re: [loopantennas] Wellbrook Loop ALA1530
An alternative would be to place a resonant parallel circuit in series with the signal path, probably after the preamp or input transformer... This would also introduce some loss but might be fun to experiment with the idea. I remember ages ago building tunable traps for BCB harmonic rejection. They seemed to do the trick then...
Ken - KB7H
--- In email@example.com, <firstname.lastname@example.org> wrote:Ken wrote on Sept. 18.
"Couldn't one build a simple series L/C circuit across the loop termination to attenuate the offending TX?
Ken - KB7H"
Ken, the L/C circuit would have to provide shunt z of approx. 1 Ohm or less because it is across a loop/Amplifier z of about 12 Ohms at 1420kHz. Also one would have to experiment to see if the loops responce at other frequencies isn't affected. However, Your idea may work with a ALA100 or the ALA100M as these use higher input z amplifiers.
I purchased the ALA100LN from Wellbrook which is a low noise preamp ranging from 50 kHz thru 30 MHz. It ships with the power supply and must be fitted with a loop of ur choice (can be a circle, a square or a delta).
Don't make it bigger than a 21 m circumference delta loop or u experience too much signal and possible unwanted products may appear.
I utilize it from VLF thru shortwave, some time as a seperate receiving antenna with the second receiver of my Flex 5000. It has not been damaged yet by the hi power transmitting antennas which are very close to it. Compared to my ALA1530 it bring 10 to 20 dB stronger signals to the receiver but with NO improvement of the signal to noise ratio.
Any way il is interesting to experiment with different loop shapes and sizes.
Best 73's de Phil FM5GB
---In email@example.com, <toddroberts2001@...> wrote:Can one purchase just the ALA1530LF headamp from Wellbrook and build theirown loop for it? I don't see just the headamp listed on their webpages so I wonder ifsomeone can buy one special order or do they sell them only as replacementsfor someone who already has one of their loops? I would need both the headamp andthe matching power inserter. Thanks for any info.73 Todd WD4NGG