Arheisel

I recently mounted a vertical on the roof and got it down to 2:1 swr. Another ham suggested that for bringing it down to 1:1 i should place something he called an "inductomatch" which he told me was a coil placed between the ground plane and the vertical element. Another ham also told me that I should start with 5 turns at 30mm diameter.

I wish to find more information about it but googling inductomatch hasn't produced any information and I was wondering if maybe there was a different name for it?

I'd appreciate any help in finding out more about this or if you got any suggestions.

Thanks!

I am trying to build a static electricity wand that can be powered from a battery (Ideally I would want to attract cat hair from surfaces for cleaning purposes but if not it's still a fun project) and I am wondering what kind of circuit could I use to achieve that purpose.

So far I'm thinking of an Ignition coil type circuit driven by a 555 coupled with a capacitor ladder but I'm not sure if that would even work. Any advice?

I've been doing some research and so far I found that the last two digits are the material, like 31 or 43 but I can't find anywhere what the first digits mean.

I'm building an amplifier stage that calls for a FT-125-43 but I can't find that specific toroid anywhere. I'm wondering if I can replace it with a FT-140-43 but I don't know the difference between the two.

I'm happy to provide more details if needed and thanks.

I'm trying to build my own 3D printed variable inductors to use as signal level filters for 6-7 MHz, as buying them where I live proved impossible.

My original idea was to use some salvaged ferrite rods and guide them through the center of the coil with a plastic screw, but then it occurred to me that I can just use a regular screw for that.

My question is how would this perform in comparison with a ferrite rod and if there are any gotchas I should look out for?

Thanks in advance!

Hi, I'm designing a 40m radio and the schematic I'm using as reference uses a Galvanometer ("S") for measuring the signal level. I'm trying to replace it with a sense resistor and a LM358 to read with an Arduino but I'm not sure what value resistor is best. As of now I'm between 100 ohms and 1K.

As per the docs:

The receive AGC circuit has an IF amplifier (Q3), a Germanium diode detector (DC biased), and a drive amplifier (Q4) which has the "Strength-meter" in the emitter.

https://preview.redd.it/hotv56yz4la91.png?width=706&format=png&auto=webp&s=89fe6d625ecb484570f7cb9616fc812d5cb03cc1