Search found 270 matches

by Andrew (grayhat)
Wed Jan 24, 2024 6:49 pm
Forum: General Discussion
Topic: What does your listening post look like?
Replies: 12
Views: 9370

Re: What does your listening post look like?

My listening post doesn't have a lot of high priced gear. The monitor on the left controls an inexpensive RTL-SDR.BLOG V3 dongle while the monitor on the right controls an Airspy RSP1A. The little monitor on the bottom is the control head for a Uniden SDS100 that is dedicated to local 24/7 P25 moni...
by Andrew (grayhat)
Tue Jan 02, 2024 5:02 pm
Forum: Questions & Advice
Topic: G7RGQ antenna
Replies: 0
Views: 4756

G7RGQ antenna

Didn't build it, but checking infos it seems to work pretty well https://www.mictronics.de/posts/G7RGQ-Antenna-1090MHz/ it's a vertical antenna for the ADS/B (aircraft) band which, looking at the NEC models I found offers a gain of around 5dBi, looking at the pics at the above URL, the antenna seems...
by Andrew (grayhat)
Fri Sep 22, 2023 5:41 am
Forum: Questions & Advice
Topic: Balun One Nine: cutting R1
Replies: 14
Views: 11633

Re: Balun One Nine: cutting R1

The antenna works great. That null is deeeeeep! I'd like to put it in the rotator I have on the roof. My question now is about the recommended 3-meter height: Would that be from the ground, or from the roof itself? Thanks for the great antenna design! from the "ground plane" if the roof a...
by Andrew (grayhat)
Mon Sep 11, 2023 3:15 pm
Forum: General Discussion
Topic: A nice and simple regen receiver
Replies: 3
Views: 13453

Re: A nice and simple regen receiver

And here's another interesting circuit https://antiqueradios.com/forums/viewtopic.php?t=373629 it's a superhet based on the classic NE602, but with a difference, the LO is a regen stage based on the LM386 (yes, not kidding) SW Superhet with Regen IF.png that "hack" allows to improve the pe...
by Andrew (grayhat)
Mon Sep 11, 2023 3:05 pm
Forum: General Discussion
Topic: The Belka (-DSP/-DX/-v3) appreciation thread
Replies: 34
Views: 25819

Re: The Belka (-DSP/-DX/-v3) appreciation thread

Late on this (have been on holidays :D) but I think that those folks are comparing apples and oranges and they just "shoot" stuff w/o even understanding what they're talking about; just consider that the Belka is a "self contained" unit, while a standard SDR needs a computer, let...
by Andrew (grayhat)
Tue Sep 05, 2023 9:15 pm
Forum: Questions & Advice
Topic: Balun One Nine: cutting R1
Replies: 14
Views: 11633

Re: Balun One Nine: cutting R1

that one is the V2, no need to scrape anything it does not have the center tap even if the PCB shows it :)
by Andrew (grayhat)
Tue Sep 05, 2023 4:16 pm
Forum: Questions & Advice
Topic: Balun One Nine: cutting R1
Replies: 14
Views: 11633

Re: Balun One Nine: cutting R1

notice that the V1 has the central tap, while the V2 doesn't so with the V2 there's nothing to cut
by Andrew (grayhat)
Tue Sep 05, 2023 12:00 pm
Forum: Questions & Advice
Topic: Balun One Nine: cutting R1
Replies: 14
Views: 11633

Re: Balun One Nine: cutting R1

Thank you, Egil. I guess I should clarify my question: How do I physically cut the resistor? Score across it with a knife? see here https://swling.com/blog/wp-content/uploads/2021/08/balun_back.jpeg you just use a cutting blade to cut the circuit trace, then use a multimeter to check if the two sid...
by Andrew (grayhat)
Fri Aug 25, 2023 10:11 am
Forum: General Discussion
Topic: A nice and simple regen receiver
Replies: 3
Views: 13453

A nice and simple regen receiver

If someone here likes fiddling with a soldering iron, here's the schematic for a regen https://www.aa5tb.com/regen.html https://www.aa5tb.com/regen2.gif I'm posting it just since I like how well it's designed while being simple, let me start from the input stage, the common gate JFET does multiple d...
by Andrew (grayhat)
Sat Aug 19, 2023 3:33 pm
Forum: General Discussion
Topic: simplest antenna
Replies: 0
Views: 11820

simplest antenna

do you have some length of old coax sitting in a corner ? Do you need a "cheap and dirty" antenna to use at whatever location ... even to transmit ? Well, read on :D Pick your coax, be it RG58, RG59, RG6 or whatever. as long as you know its characteristic impedance, say 50.or 75 Ohm, now ....