2013年10月25日 · 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 ...

2019年12月9日 · A physically half-wave dipole isn't resonant. As you say, it has an impedance around 73+j43 ohms. Since the reactance is non-zero, it is by definition not resonant. Any manner of matching devices could be added to the antenna, and considered as a whole, they would make a resonant system. But that's not what people usually mean when they say "resonant antenna". Instead, the antenna can be made ...

Datasheets for ferrite materials are usually filled with incomprehensible graphs with greek letters. 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?

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...

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 ...

2023年11月1日 · 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.

2021年10月24日 · Since it is "technically" a complete QSO I log it (in DXKeeper) but don't upload to e-qsl or LotW unless the other party does. If he does, I'll upload: if he doesn't I assume he has it as incomplete. I think this saves a lot of time later, looking up the QSO details in the .txt log! Some folks simply don't bother with "73". 73 Dave - K1DJE

2022年5月10日 · 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.

2020年1月8日 · I'm new to CW and one thing I couldn't figure out is when I supposed to send "E E". Let's say I'm calling CQ and somebody answers me. The QSO is almost over. Should it be ended like this: - TNX FE...

2015年12月15日 · Per the above; although correct based on a free space dipole impedance of 73 ohms, I would suggest that very few practical dipoles are close to this based on the typical proximity to ground and the slanting, inverting or angle of …