All Questions

I am using a simple Baofeng H6 dual band radio and I programmed weather channels. Well, on frequency 161.77500 I am actually picking up WGN, a local tv network. This frequency should be reserved to ...

Some times ago I tried to decode the signal from a weather radiosonde (RS41) passing in my area using a cheap RTL SDR (using both standard antenna and a home-made one, with similar result). The ...

The idea was to send GPS data from the rocket to the ground station at 433 MHz using a Lo Ra transmitter - mainly to help locate it once it lands and also to provide in-flight telemetry. I have a ...

I have searched, installed, and tried every package there is to get AIS processing using the gnu-radio companion to no avail. I tried installing gnu-radio both with conda and apt on Ubuntu 20.04. The ...

The popular question "What is the relationship between SWR and receive performance?" asks if a receiver with a well-matched antenna (low SWR) beats a receiver with a poorly-matched antenna, ...

As a US license holder (and duel citizen of the US and UK) I know that I can operate in the UK for a couple of months using the M/W2*** prefix, while holding Amateur Extra, but I cannot apply for a UK ...

This radio has a commercial mode but no where that I can find does it describe which commercial license. Looking at the tag under the battery... FCC ID T4KD887UV https://fccid.io/T4KD878UV ...so part ...

I saw a recent answer that mentioned "mfd" as a unit of capacitance, and I can recall having seen that term in old schematics and ham radio articles. I've also seen other non-SI unit ...

Recently I've made a simple single IF superheterodyne SSB receiver for 40 meter band. The schematic is available here [PDF]. VFO and BFO are based on Si5351, the AF amplifier is LM386. It works OK but ...

I have been using an Ettus B200 SDR to receive FT8 transmissions in the 2-meter band (144.174 MHz) using the WSJT-X software. Signals are received using a telescopic antenna inside on a window ledge ...

What is ALC on an HF transceiver? What are the disadvantages (if any) of operating using a rig without ALC? What might be the difference between a good and bad implementation of ALC?

In in Russia I saw a phone cable called "field cable" (провод полевой П-274-М). It is a loosely twisted pair with some iron strains added alongside with copper ones. I tried to lookup ...

I'm planning to use a multiwave horizontal dipole oriented to work comms toward Alaska from Colorado. That ends up being awkwardly oriented to work east coast and Europe. If I placed a second ...

What is the signal processing model of a simple regenerative or super-regenerative receiver? Is it just a linear 2-pole IIR filter with gain? How does a single regen control knob control both ...

it's well known that in a linear and equispaced antenna array, the array factor is equal to: The array is then called uniform if $|I_n| = I$ is the same for all elements. The phase terms $\angle I_n$ ...

In this thesis the following model for an antenna is proposed: It is seen as a 2 port network, in which only port 1 is accessible (port 2 is an imaginary connection between the antenna and the free ...

Newbe here, I was looking through repeaters in my area and I noticed that there were a few repeaters that shared the same call sign(even though they run on different frequencies). Does this mean that ...

I have a basic question about sweep times and number of points. My frequency span of interest is: $f_{span} = 30\ \rm MHz$ My resolution bandwidth is: $RBW = 10\ \rm kHz$ The minimum number of points ...

CQ CQ CQ de BH4FHO. I have been fixing some radios recently - buying used radios for cheap, fix them up and modify them to transmit in ham bands. When testing them out, I am using my Baofeng DM-1801 ...

I am a beginner with not much experience in HF. My shack consists of a Xiegu G90 connected with 20ft of RG-8x to an MFJ 1982 end fed half wave antenna. There is a small coil of coax next to the ...

Would it be possible to make an alert radio... for shortwave? Out of something like Arduino, or RPi. Sort of like the NOAA Weather Radios. I got to thinking one day. Say you wanted to send a message ...

Here is a crystal filter used in uBITX transceiver: I've never seen such a topology in any other transceiver and decided to invest some time in exploring it. Turned out it's quite interesting. Eight ...

Very new to ham radio! Have install President Lincoln 2+and have been playing some, only listening!! Can’t seem to tune in 146.520 can anyone help?

This L network intend to transform Z1 to 50ohms. The design was made using a smith chart: The s-parameters plotted (S11 red - S22 green) in the smith chart is done sweeping the frequency from 200MHz ...

let's consider a simple linear uniform spaced array: We know that, from elementary array theory, the total pattern (for instance in terms of E-field) may be evaluated, in case no phase shift is ...

Not necessarily an amateur radio question (but perhaps a licensed amateur should know the answer?) - I note that the specifications for marine VHF radio operating in the 156-157 mhz band call for both ...

I have an old "Walkera-RC 2.4ghz Radio Transmitter WK-2401" radio transmitter from an RC Helicopter. I want to use this transmitter with a receiver in order to transmit some sort of data ...

The Kenwood TS-570S comes with a warning against using the internal antenna tuner for antennas with SWR > 3, even though it may tune (e.g. at SWR 3.5 or 4). It says the transceiver or antenna may ...

I know that 144-148 and 156-157 mhz ranges are in use, and various fire/ems/police, but outside of that, I see a lot of earth-to-space, weather stuff and space research allotments (talking about ...

My understanding of a naive PSK scheme is that you have some frequency(s), f(n), at baseband, and you modulate information by shifting the phase (what "point in time") the signal is at. Isn'...

I've put up a "random" length long wire antenna for HF in my yard at about 124ish feet about 15' off the ground. I got this length from an online resource. Here's my questions: How does the ...

I'm very new to this radio stuff and I've come across a problem. I have two BF-888S', along with two other radios. (Binatone Terrain 750) All of which are on the same frequency and have the same ...

let's consider this two planar biconical dipoles of total length and width each one 10mm, at a distance D = 25.6mm. They are excited with the discrete ports in the picture, which corresponds in this ...

I'm trying to build a UHF repeater using two Motorola radios. I have a cable connecting the two radios that was built for doing such a project. The radios have been programmed for the appropriate ...

Please forgive me, my native language is not English. I'm new to radio, but I have several years of programming experience. I have a raspberry pi 4 model B (...

I want to build a common mode choke for my end-fed wire antenna, using turns of coax through an FT140 or FT240 ferrite. I can find various finished products for sale, but I want to make my own. I ...

I'm trying to identify the type of RFI I'm seeing on the waterfall in the picture below. It occurs mainly at night, every night, starting at about 6:30 p.m. and ending in the morning, and I have yet ...

Imagine a group of eight or more vertical masts. On each mast is a Yagi antenna pointed upward toward the sky. The elements are inverted with the idea being that the incoherent RF coming down is given ...

I am getting no NOAA weather broadcasts, after loading all NOAA weather channels into memory or entering the frequencies manually on a new Baofeng UV-5R?? Why? Do I need to do something else?

I want to transmit an ASK signal with GNU Radio and HackRF, the parameters are: Frequency: 27.12 MHz (ISM) Sample rate: 2MSPS Symbol rate: 2000 bps Samples per symbol: 1000 The flowgraph currently ...

In short I am trying to receive SSTV Images from the ISS (145.8Mhz) and I all have is a simple "bunny ears" dipole antenna. In what configuration (straight, vee shaped, upside down vee, ...) ...

I think I'm having a hard time understanding HF antennas because they go against everything I've been taught about analyzing circuits. If we look at a dipole antenna, there is the highest current in ...

When I transmit the there is a delay in the receiving. When I let off of the mic it still transmits for a few milli-seconds. The transfer to receive is not instantaneous. Which setting controls this ? ...

I have a mid-era Hammarlund HQ-129-x. It sounds great if I don't count the motorboating. But the problem is in the middle bands. I got the radio way out of alignment, and managed (I think) to get ...

let's consider a printed dipole on a substrate with a GND plane: I've seen many times an equivalent model which uses transmission lines like this (reference): This model is useful to understand the ...

Let's consider a simple antenna array. For instance, this three-elements equispaced dipole array: Each dipole is connected to a signal voltage source. It's well known that it's possible to choose the ...

I chose the resistor values in the following schematic to set the DC bias point of VCE=6V and IC=5mA because the transistor data sheet gave the S-parameters at 162MHz for these values. I learned how ...

I can explain almost every part of the Kenwood TM-D710(G) display except the letter "D" that appears on the second line of the B band next to the power level. I've poured over the manual and ...

GNU Radio v3.8 with Qt-GUI on Ubuntu 20.04 Before starting on something new I always test my setup with this GNURadio hello world flow graph which I know for sure, that it used to work. The other day, ...

A little background. My uncle devoted part of his late life to ham radio, he had his callsign and would go install/fix radio systems all the time,travel across the country and would teach newcomers ...