|
- Why do hams often conclude messages with 73?
The usage of "73" for such a purpose comes from the Phillips Code, originally devised in the era of telegraphs to speed up transmission of common messages by mapping them to numbers "73" mapped to "best regards" or "my compliments" and was intended as a general valediction for transmitted messages It is still used for that purpose today in morse code transmissions and often makes its way
- What is the impedance of an end-fed half-wave antenna?
Model the 1 2 wave center fed antenna using the wire size, altitude, and all location attributes to determine the center fed impedance divide 600 by the 73 ohms or whatever you calculate the center fed impedance to be then multiply the answer by 600 --- you're home Example: 600 73 = 8 22 × 600 = 4900 600 73 = 8 22 × 600 = 4900 ohms This is the original and correct quarter wave transform
- Understanding how antenna mismatch can damage a transmitter
Antenna impedance is largely due to radiation resistance: a center fed half wavelength dipole has a radiation resistance of about 73 ohms Resistance due to heat loss is negligible, and I believe reactance negligible as well Let's say we have an oscillator consisting of a 1 MHz voltage source (30V RMS) in series with a 75 ohm resistor
- ft8 - Long callsigns in WSJT-X? - Amateur Radio Stack Exchange
In other messages during a QSO with you (signal report RRR 73 RR73), either your callsign or the other party's callsign will be replaced by a 12-bit "hash" instead of transmitting the callsign directly When callsigns are hashed, they are displayed in angle brackets like <KC2G> in the wsjt-x GUI
- How to estimate a dipole feedpoint impedance? - Amateur Radio Stack . . .
An ideal dipole, at resonance, will have an impedance around 73 ohms A folded dipole, around 280 ohms How can I calculate the impedances when not at resonance? Let's assume I have a span of 15M
- What is the peak voltage at the tips of a dipole antenna?
What is the peak voltage present at the very end tips of half-wave dipole antenna in free space, and how might this peak voltage relate to transmitter type, transmitter power, RF frequency vs ante
- Core mix preferences for a balun (or unun) vs a choke
The MnZn ferrite cores (Mix 31, 73, 75) have high permeabilities above 800 µ, have fairly low volume resistivity and moderate saturation flux density They offer high ‘Q’ factors for the 1 KHz to 1 MHz frequency range
- How does one read a ferrite datasheet? - Amateur Radio Stack Exchange
For example, Fair-Rite's 73 material: What's a μ′s μ s and a μ′′s μ s ″? What do these numbers represent, and how can I use them in amateur radio? Do they allow me to predict inductance or losses of inductors made on cores of this material? What is the relevant math?
|
|
|