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1500 questions
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Has an amateur radio communication ever taken a path outside the Earth-Moon system?
As a bit of curiosity, I was wondering what the longest path ever used by amateur radio operators has been.
Of course the opposite side of the Earth is no problem with a good HF station. And you can work long-path, so that's at least the…
Phil Frost - W8II
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6
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2 answers
How to increase antenna aperture?
I know that in the short wavelength region, where parabolic antennas are used, the aperture can be increased simply by making the dish larger, as is the case with the radio telescopes. But how to do this in the RF? If I make a half wave dipole…
Tr00rle
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6
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3 answers
Antenna options
I am considering a new ham station in a relatively urban environment on the South coast of England, and would like like some ideas / feedback on antenna options.
Aim is to get reasonable performance for 40/20/15/10m bands with 100W TX power from an…
Oliver Schönrock
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What is a 'Call' Channel?
While programming my Icom radio it has MR (memory)channels, VFO (Variable Freq) channels and Call Channels. What are call channels as comparred to memory or vfo channels? What is their use?
Steve Miller
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6
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2 answers
Can an oscilloscope be used as an RF voltmeter?
I just recently acquired a slightly functional Icom IC-735 HF radio, and am trying to resurrect it.
The service manual outlines procedures that specify the use of an RF Voltmeter, which I do not own. I do have a Tektronix 2236 dual channel 100MHz…
user14945
6
votes
4 answers
Can SDR receivers be detected remotely?
It's my understanding that active superhet receivers can be detected by looking for the emissions from the local oscillator, particularly because the LO's frequency is usually set at some fixed offset from the carrier.
Is a similar technique…
chrylis -cautiouslyoptimistic-
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6
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6 answers
If receive performance doesn't depend on SWR, then how can I tune my manual HF antenna tuner by band noise?
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, with everything else being equal. The consensus opinion…
rclocher3
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6
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What does ALC do on a transceiver?
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?
hotpaw2
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6
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2 answers
How is phone cable with iron called?
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 something similar but I failed to find it.
I used phrases like…
k1zmt
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6
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1 answer
How to stack circular polarised antennas
I'm interested in stacking a pair of circularly polarized "crosshair" antennas. Do I construct such as both antennas are in phase with one another then match the two signals in phase via the coax line, i.e. equal length, or should I rotate one by…
Ben
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How does a digital demodulator know which level it is reading?
I have recently started getting into wireless digital communications and I read about QAM modulation.
But I am a little confused as to how the receiving demodulator would know which symbol it is reading.
For example with 64-QAM there would be 8…
YellowBadger
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6
votes
1 answer
Secure communication over Amateur-band HSMM / 802.11 in the United States
I'm quite interested in 802.11 over amateur radio frequencies; however, all I have done at this point is reading (I don't have a ham license yet). The conventional wisdom (espoused in this ham.SE answer) is that you cannot encrypt radio…
Mike Pennington
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0 answers
How to estimate input and output impedance of an amplifier?
I'm trying to figure out how to design power amplifiers which input and output are properly matched to 50 Ohm. My thinking was that the most bullet proofed approach would be to model an amplifier in LTspice and estimate R as U/I on both input and…
Aleksander Alekseev - R2AUK
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6
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4 answers
What nations still require Morse code testing for Amateur radio license?
Going a bit further I'll ask, for which licenses (all or just for licenses for HF operation) and at what speed (5 WPM, 10 WPM, none specified)?
The reason I ask is because every so often I'll see people from the USA wanting to visit another nation…
MacGuffin
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6
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4 answers
50Ohm Coax presents 50 Ohms of impedance on which frequency?
Either there's a simple answer that I'm not finding in a spec sheet somewhere, or, I'm asking the wrong question!
Adam Palmer
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