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1500 questions
6
votes
1 answer
How to detect a tone on an FM Frequency using an RTL SDR receiver?
I'm transmitting a simple tone which lasts 50 ms using an FM transmitter. I can see clearly this tone being received on my RTL-SDR device when I look at a spectrum graph (using GQRX).
I need to call a linux kernel function a soon as the tone is…
Ash
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6
votes
1 answer
Is it legal (in the US) for a server on APRS-IS to relay replies from non-hams to a ham?
I've heard two sides to this. On one hand, sites that allow you to send messages into the APRS-IS network, for relay over RF, demand you enter a call, as "only licensed hams may cause a message to be relayed over HF". On the other hand, gateways…
Chris
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6
votes
4 answers
Why can't VHF / UHF be used with ionosphere reflection?
HF radio can be reflected by the ionosphere, giving very long range communications.
Why can't VHF / UHF used with ionosphere reflection?
Is it due to the attenuation of the atmosphere over that distance with VHF / UHF wavelengths?
Or is it to do…
DarcyThomas
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6
votes
3 answers
Is it possible to have 2 FM transmitters on the same frequency?
Has there been any success in transmitting two simultaneous FM signals? I am assuming if the phase is correct, and the signals are identical, it would be possible.
That would be really nice if newer repeaters could find a way to broadcast two…
Skyler 440
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6
votes
2 answers
Is it possible to transfer an area-specific call sign from a deceased relative?
I passed my Technician exam today and my grandma, who's been a ham for decades, suggested that I could try to get my grandpa's call sign. He passed away several years ago, but his FCC registration is still marked active, expiring later this year.…
Eric Angell
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6
votes
2 answers
Is it legal to monitor police and weather channels without a license?
I have two HT's that I bought from Baofeng for emergency use and I don't have a license. I was wondering: is it perfectly legal in the USA for me to be monitoring police and weather channels without a license so long as I don't transmit on any…
Brian
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6
votes
2 answers
Power dissipation in transmission lines?
I was wondering, does the impedance of a transmission line have any effect on the power it dissipates? I'm familiar with the fact that an impedance equal to the load will provide maximum power transfer (and dissipate just as much power as the load)…
s3c
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6
votes
2 answers
75 watts and a mag mount antenna
I am planning to get a Yaesu FT2900R 2 meter rig for my 2001 Honda Accord. With my 5w FT60, I wasn't able to reach repeaters that were any more than 10 miles distant (I live among mountains.) How far can I reasonably expect to get with 75 watts…
user228
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6
votes
1 answer
FM radio in car gets interference from APRS beacon
The FM broadcast radio, factory installed in my car and usually tuned to 88.6 MHz, gets some interference from the 5W APRS transmitter on 144.800 MHz. It sounds like if the sensitivity of the broadcast FM receiver would go down a bit temporarily:…
oh7lzb
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6
votes
1 answer
Kenwood D710: loud fan noise when used in the shack
The fan in the Kenwood D710 mobile radio is turning on on every transmission, including the periodic APRS beacons. This happens even when there is no actual need for spinning it, and is very annoying in a quiet shack (as opposed to under the car…
Georg DO1GL
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6
votes
1 answer
APRS: WIDEn-N vs. TRACEn-N
The suggested APRS digipeater path is WIDE1-1,WIDE2-1 for the most use cases. According to the specs, this ensures two retransmissions by fill-in / regular digipeaters around the sender, without the digipeaters adding their own callsign to the…
Georg DO1GL
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6
votes
2 answers
Does a tube based HF transmitter need an antenna tuner?
With the adjustments on a transmitter such as a Yaesu FT-101E, is there any purpose for an antenna tuner, or can you accomplish the same thing by adjusting the loading and other controls?
K9KRB
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6
votes
1 answer
Is it legal to use an R identifier for my repeater in the USA?
I have been told by someone that my repeater is not allowed to have a slash r on the end of transmission because that is an identifier for the Russian Federation.
Almost every repeater locally uses that, for example KDØWHB/R.
Am I allowed to use…
Skyler 440
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6
votes
4 answers
Advantages of using Digital Code Squelch
I am trying to decide whether or not I should use a CTCSS (Continuous Tone-Coded Squelch System) or a DCS (Digital Coded Squelch) for my mini repeater I just set up.
What are the advantages of using a DCS over a CTCSS?
I am in an area with a lot…
Skyler 440
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6
votes
1 answer
How can I get started with a Home Brew QRP?
I want to build a simple 40 meter CW transmitter and Receiver pair. What should I do to get started into home-brew HF RF devices?
Skyler 440
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