Hi Andy I use Wellbrook loops - 1530 for hf (150 kHz - 30 MHz) and 1010 (10 kHz - 10 MHz) for lf. They work very well with my SDR-14 and SDR-IQ. The loop feed box is filled with a potting compound to
Hi Chris I didn't realise you were a member of this group. Thanks for the link - I have been studying your other paper on complementary push-pull amplifiers for active antennas but hadn't seen your l
On 12/16/2011 6:49 PM, DENNIS EASTERLING wrote: I read with interest the comments about the Welbrook Loop, raised by the review by Steve G0KYA in this month's Radcom Any chance to have a PDF copy of
Using the augmentation gives you a similar input impedance at far less current. It gives you the opportunity to operate the transistor at it's best NF. Chris
You might want to add this to your list of suitable alternatives: http://www.home.earthlink.net/~christrask/Paper009.html Chris Trask N7ZWY / WDX3HLB Senior Member IEEE http://www.home.earthlink.net
Andy es Co A friend lent me one of these loops and I was not impressed with its performance compared to my resonant inv L system for 137. Likwise on 500 Khz compared to my 1/4 wave inv L is was well
This sort of outline concept for a balanced augmented configuration... http://www.g4jnt.com/LFLoopAnt.gif Not sure if the emitter centre tap needs to be decoupled to actual ground. If not, the whole
Mal, They are mostly marketed to swls and thus are not protected against large signals coming from a nearby transmitter! -- 73 Warren K2ORS WD2XGJ WD2XSH/23
That results in far higher distortion as the emitter signal voltages are not symmetrical, and you cannot force them to be. Chris Trask N7ZWY / WDX3HLB Senior Member IEEE http://www.home.earthlink.ne
A very interesting circuit concept - I hadn't heard the term "augmentation" before. (It looks to have something in common - and completely turned upside down - with the bootstrapping technique used t
Clifton Labs used a portion of that paper in their latest active monopole amplifier offering. They added a bipolar emitter follower stage between the JFET input and complementary output to further u
This one from Chris has an input stage similar to the design I did those years ago, but with added feedback and more. The common base push-pull running open-loop, if memory serves, gave about 0.5 ohm
