Wenzel "loopifier" kit - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: January 24, 2021, 10:54:28 am
content: Just stumbled upon this kithttps://rhelectronics.net/store/diy-kit-of-active-amplifier-magnetic-hf-antenna-3mhz-30mhz-for-hula-loop-shortwave-radio.htmlthe kit uses the same design of Charles Wenzel "loopifier"http://techlib.com/electronics/antennas.htmlwhich I've built in some samples, the result is a nice performing tuned loop antenna, tuning is achieved through a varactor, notice that the kit doesn't include the bandswitch relay and molded inductor which allow full coverage, so one will need to provide his own, the price seems rightSure, building it directly would be easy, but if one doesn't have the bits and pieces, the kit may be okwhat do you think ?note: I've no relations with the seller and didn't try the kit, my samples were built from scratch

author: coppercone2
author_rank: Super Contributor
timestamp: January 25, 2021, 07:40:19 am
content: the price is a bit much, i think $20 would be fair, since its a copy of a design online, so the normal engineering development price can be reduced. Or they could make the kit better and throw in a GDT, fuse, BNC and LED. They should make it a solid build so it has an appeal over deadbugging. Right now if I wanted that, I would dead bug it with the $3? of parts, depending on the quality of those capacitors. Fuse holder = really good reason to put it on a PCB. They are annoying to change. Granted you might have the fuse in the other section of it, so they could include another PCB for an altoids tin with the power rail filter, if it came with 3x panel mount coaxial connector it would be a OK value, but I see the problem with some people using UHF connectors or whatever.I would say the only thing the kit can add to increase value without pigeonholing someone is a GDT and TVS diode.Now it also depends on that trimpot. If it has a boo-rang or bo-chen, then its a complete fucking ripoff that gives you 30 cents of parts. It needs to be a legit bourns, those actually really suck when you counterfit them, the drift is like 8x higher with temperature. I only give it that fair price of $20 if those jellybean parts are brand name. Resistors too, I am not going to attack it on the idea that it uses carbon film, but the resistors need to be real ones that have the thick leads, not the counterfeit chinese ones that are made hair thin. If it used legitimate carbon resistors, I could say its reliable, and if it used thin film resistors, I could say its pretty stable, and you could assume that the low skill person buying that would actually get an improvement over the parts in their junk box, which are likely amazon ultra thin lead not really reliable resistors, real parts would do the PCB more justice and increase its value, and someone that cares would not be embarrassed and feel like they have low quality equipment.Oh yea and the capacitor should be a brand name one too.

author: A.Z.
author_rank: Super Contributor
timestamp: January 25, 2021, 06:00:46 pm
content: thank you, and yes price is probably too high, given that they didn't include the tuning pot, the additional inductance and the bandswitch relay; as for the trimmer, it seems to be one of the mods of the original circuit, and if I'm correct, it controls the gain

author: coppercone2
author_rank: Super Contributor
timestamp: January 25, 2021, 08:57:19 pm
content: I think those parts are not added because they think you might want to customize it, its difficult to make things work with different peoples chassis, i.e. some people might want small form factor panel potentiometers and others might want 10 turn pots.. so you get a configurator problem. Theoretically you can try to do something cool like make it ultra flat or put a servo on it or something like that.. but realistically this is a small number of people. If its for a school a teacher could make it multidisciplinary by having them design some 3d printed gear box for motor control, to have a electromechanical theme, or maybe involve junior? EE and mechanical engineers for the same project.