Active Antennas
开云体育Previously wn4isx posted a link to: The reference refers to an improved version but there is no link to it. Does anyone know where I can find the improved version schematic? Any other suggestions? I remember seeing an article about installing an active antenna and avoiding extra local noise, but I do not remember where I saw it. Using SMT components is not a problem. Thanks Bertho ? |
开云体育After spending too much time searching and reading about active antennas and building a library, I visited Amazon. Search for “Mini-Whip Antenna”. There are enclosed ones, but I ordered a promising looking open one for $12 to play with before building or getting a permanent one. Bertho |
开云体育I found that one, , ?but I have not found the second part one in the pictures that is discussed with improvements. I found this one that looks promising: Bertho ? From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 9 March, 2025 11:03 To: [email protected] Subject: Re: [electronics101] Active Antennas ? Pedid y recibiréis ? Simple and better circuit for MiniWhip antennas ? The 2SC5551A might be a viable substitute for the 2N5109 in the original PA0RDT Mini-Whip. It has a lower Ic but better Ft. This is one of my way too many projects that I might get around to before I run out of time on this side of the grass. ? |
开云体育Another extensive active antenna link!? Thanks! More reading ? Time allowing, I will build something. ???Right now, I got to take care of business as a priority so getting something that reasonably works is way to quickly fire up the SDR. For $12 arriving in two days looks like a good choice.? Being open, it allows me to see the design.? I obviously need to add a simple enclosure. I have lightning rods on my home, so I plan to attach the antenna to one of them.? I will ground the bottom end of the coax to the buried ground system. That reminds me:? When I built the house, I used 1” regular copper plumbing to run a low impedance ground connection from buried lightning ground system to my workbench. The plumbing inspector had a fit since the pipes were not on the plumbing drawings. Bertho ? From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 9 March, 2025 12:56 To: [email protected] Subject: Re: [electronics101] Active Antennas ? While I learned the required subject mator for my two degrees in university, the main thing I learned in university was how to research. It was a bit of a challenge to transition to the web but well worth it it. At my last two jobs I was the unofficial "researcher." ? Glad to help. ? I'd seriously consider breadboarding a stock PA0RDT dead bug style, isolate the 'plate' with a dremal tool. The J310 is easy to locate, the 2N5109 might be a challenge. ? Avoid active antenna designs with MOSFETs as the gate capacitance will kill the incoming RF. This can be avoided but it gets way too complex for the performance of the antenna. ? This is another resource, I've built the antennas using 6CW4, I used 13CW4 because I had them. ? This design works extremely well...OK can't copy the link as it brings up the graphic. Look for the design that uses 3 6CW4s. ? ? |
Bertho