Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Most Popular

more tags
1500 questions
7
votes
1 answer

What happens to your callsign if you migrate?

If, as an amateur radio operator, you're licensed in one country with a callsign, let's suppose, the US and you migrate to, say, Germany, will you have to reapply and obtain a new callsign? What if your migration is temporary, and you're only…
Amin Shah Gilani
  • 832
  • 1
  • 7
  • 19
7
votes
3 answers

Long range communication with just 1W of power?

Is it possible, and how can I setup communication between stations 1000km apart from each other by using just 1W of transmission power? By communication, I mean: It can be text based It can be very slow. It's okay if I receive a small message in…
Akshit Mehra
  • 171
  • 4
7
votes
2 answers

Water cooling a GS-35B in lieu of air cooling?

Does anyone know how to --or have any experience with-- water or oil-cooling the anode? Since forced-air cooling is required, the sound from the blower and the exhaust air would be too noisy for my ears. They look similar to an 8877, but have…
Mike Waters
  • 7,948
  • 4
  • 18
  • 51
7
votes
1 answer

How to determine number of turns for a 1:1 balun?

I would like to make a 1:1 balun with М1000НМ ferrite core (magnetic permeability - 1000) and 1 mm thick copper wire using triple bifilar winding. Unfortunately I didn't manage to find a clear instruction on how to determine the required number of…
Aleksander Alekseev - R2AUK
  • 4,272
  • 15
  • 52
7
votes
1 answer

Antenna for receiving 868MHz rocket telemetry: QFH(QHA), Helical, or?

I'm building a radio communication system for an amateur rocket project. We've decided to use LoRa 868MHz system. My question is, which antenna for the ground station will be the best choice? We're aiming for both vertical and horizontal gain, as we…
leller
  • 181
  • 2
7
votes
2 answers

What is inside a 50 ohm termination?

I see RF applications requiring 50 ohm termination to avoid any open port reflections. Curious what is actually inside a 50 ohm termination connector. Is it simply a 50 ohm resistor? But then it is rated for certain frequency range, so makes me…
eecs
  • 159
  • 1
  • 5
7
votes
1 answer

How to make a ferrite bar antenna for RTL-SDR?

I bought a RTL-SDR (blue one with little MCX antenna). I modified its Q branch, and can receive short wave radio with Degen 31MS antenna now. For MW, Degen 31MS antenna has a ferrite bar antenna coupler to work with the internal antenna of the…
jac123
  • 73
  • 5
7
votes
4 answers

How can the voltage at the center of a resonant half wave dipole be zero if the input impedance is 75 ohms?

If the input impedance of a resonant half wave dipole at the feed point is 75 + j0 ohms, then if an AC sine wave voltage V is applied to the feed point, how can the voltage at the center be zero ? Ohms law always applies correct ? So for the rms…
Andrew
  • 3,675
  • 12
  • 35
7
votes
3 answers

Impedance Matching between RF Amplifier Stages

I'm in the process of building a RF buffer-amplifier chain for a VFO and I'm experiencing a design issue trying to impedance match between the sections. The issue I'm having is that many (most) of the circuit designs documented are characterized…
Buck8pe
  • 989
  • 5
  • 14
7
votes
1 answer

FCC callsign with incorrect group letter

I just passed my technician exam and received my callsign from the FCC (KC1KHV). I was surprised by the two letter prefix, which seems to come from the class D group. According to the FCC documentation on the topic, a technician license should…
larsks
  • 608
  • 3
  • 13
7
votes
4 answers

Efficiency of short dipole receiving antenna

For a transmitting dipole antenna, its length is important. If it is close to half the wavelength, it will be efficient and most of the input power will be radiated. How important is the length of dipole in case of receiving antenna? Will a dipole…
thbnju
  • 71
  • 1
  • 2
7
votes
2 answers

Learning RF electronics

I've been studying and building test circuit for actually several YEARS now, so far with no success. It sounds ridiculous but it's true. So I feel like I have a good understanding or RLC circuits, I can calculate phase shifts and impedances etc., I…
user13171
7
votes
4 answers

Why is the 70cm band commonly referred to as the 432MHz band?

I keep reading and hearing the 70cm band (420-450 MHz depending on local regulation) referred to as the 432 MHz band, particularly by older hams. Why?
Jacob
  • 442
  • 3
  • 11
7
votes
2 answers

What SDR software is available that provides internet control?

I plan to use a SoftRock Ensemble RX II to receive HF transmissions. I'd like to be able to use it wherever I am when I have a few minutes, though, so I'm wondering what software exists that would allow me to control the receiver over the…
Adam Davis
  • 12,125
  • 2
  • 47
  • 107
7
votes
4 answers

Is there any downside to consolidating on BNC connectors for HF?

I'm new to ham and quickly finding that the new and old equipment I'm accumulating at an alarming rate has an equally alarming array of connectors: UHF PL-259 BNC SMA Type N Is there any downside to consolidating on BNC as my main connector and…
RoboKaren
  • 844
  • 6
  • 15
1 2 3
…
99 100