Hot answers tagged

5 votes
Accepted

How do you calculate peak voltage given VSWR caused by impedance mismatch in a 50-ohm system?

Before going forward I want to make a quick note: your example of 273V is the RMS voltage it takes to put 1500W into 50 ohms — but if you're concerned about dielectric breakdown then you actually want ...
user avatar
  • 9,275
4 votes
Accepted

Voltage wave in transmission lines

A transmission line is linear, which means we can consider the voltage at any point to be the superposition of two other voltages. Asking what they are "physically" may or may not be a useful ...
user avatar
4 votes

Power supply for shortwave portables

I wouldn't risk directly connecting a 9.6v battery to a radio that expects 5-6v. The simplest solution would probably be the diodes mentioned in the comment to your question, but as the battery ...
user avatar
  • 716
4 votes

How do you calculate peak voltage given VSWR caused by impedance mismatch in a 50-ohm system?

For amateur use, breakdown from overvoltage is probably not something you need to worry about. The main limits to power handling of a cable come from resistive heating and dielectric heating. Arcing ...
user avatar
  • 8,235
3 votes

How is working on DC high voltages as in a tube radio different from 120VAC?

800 volts is far more likely to burn you. Just doubling the voltage from 120 to 240 will quadruple the power heating your flesh. This is just basic Ohm's Law: [P=E*I] DC is one nasty customer: It ...
user avatar
  • 7,544
3 votes
Accepted

How much voltage is on a typical high power (1000mw) 2.4Ghz WiFi antenna?

The answer is "it depends". It depends on the Antenna design, but lets look at an example: A typical (license free / home / consumer) installation of WiFi is 100mW (not a 1000mW as your post ...
user avatar
2 votes
Accepted

Determining whether signal meets the 12 dB SINAD voltage

The specification means $0.15\ \mu\text{V}$ at the input terminals of the receiver, so this voltage across a $50\ \Omega$ load. Power in a resistor can be calculated with $P={V^2}/{R}$ so $0.15\text{ ...
user avatar
  • 8,235
1 vote

How is working on DC high voltages as in a tube radio different from 120VAC?

First of all, a voltage of 800VDC can be very dangerous if you happen to be touching anything at ground potential. An 800V potential is REALLY eager to pass some current down to ground, compared to a ...
user avatar
  • 4,409
1 vote

Determining whether signal meets the 12 dB SINAD voltage

You must also know the impedance of the receiver which is typically 50 ohms. Convert the received signal from dBm to Watts. Then the input voltage is sqrt ( P * R ) We usually work this the other way ...
user avatar
1 vote

How much voltage is on a typical high power (1000mw) 2.4Ghz WiFi antenna?

This doesn't actually answer your question per se, but I think you have an important misconception: An antenna is not a resistor. Of course you know it's not, but in particular, an antenna having a ...
user avatar
  • 23.1k
1 vote
Accepted

Measuring RF voltages with a multimeter

For an ideal meter, sure, it's possible. However, most multimeters are not designed to work at RF. There are all sorts of problems: what effect does the input capacitance have on the measurement? What'...
user avatar

Only top scored, non community-wiki answers of a minimum length are eligible