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1500 questions
6
votes
2 answers
Small band-pass filter for HT?
I'd like to add a band-pass filter to my Baofeng UV-82 to make it comply with the spurious emissions requirements. Ideally it would be a rigid device with SMA or BNC connectors that would fit between the radio and the antenna.
I'm open to building…
mrog
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6
votes
1 answer
Why is the neper a useful unit for transmission line calculations?
SWR Measured at the Transmitter versus SWR at the Antenna says the neper is "a more convenient unit for transmission line calculations".
Why exactly? What is a neper, and what about it makes it more convenient than the more common decibel? Are there…
Phil Frost - W8II
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6
votes
3 answers
What is dB(μV/m), and what are its applications?
Many radio coverage tools yield results in dB(μV/m). For example, CRC-COVWEB or nearly any tool based on the Longly-Rice model.
The unit occurs in regulations sometimes as well. For example, maximum permissible exposure limits may be given in V/m,…
Phil Frost - W8II
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6
votes
1 answer
What makes a good emergency-capable QRP rig for travel?
It's wintertime, which drives the concept of emergency preparedness here above the 45th Parallel. Am emergency-capable QRP rig is an excellent item to stuff into one's Go Bag or vacation gear, always but especially now.
What's an essential minimum…
K7AAY
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6
votes
2 answers
Can I transmit on 2 frequencies simultaneously?
Lets say I want to call out CQ on 145.340, 145.940, and 146.140 at the same time, am I allowed to call simultaneously on all three then monitor all three for replies?
Skyler 440
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6
votes
1 answer
Sine signal distorted in GNU Radio
I am starting off with the Ettus Research lab-1 - lab-5 tutorial to learn GNU Radio. I have set up the following super simple flow graph. I am using WX GUI as it is what used in the tutorial.
This flow-graph works well for low frequencies. As…
Denis
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6
votes
3 answers
Is there a special term for amateur transceiver speakers or anything that makes them different from any other kind of speaker?
When I bought a secondhand FT-7800R at Field Day 2017, I received an MLS-100 external speaker with it. I installed it recently and having the speaker more than an inch away from the radio's mounting surface is great.
I'd like to buy more external…
William
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6
votes
1 answer
Why do some antennas list modulation type alongside power rating?
Looking at HF antennas I've noticed that occasionally I'll see power ratings similar to "200W (SSB)".
Why would the modulation matter for an antenna's power output rating, and in the absence of other information how does one properly derate such an…
Adam Davis
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6
votes
2 answers
Dummy load construction and heat dissipation
I'm building my own dummy load, consisting of resistors submerged in liquid paraffin (or something similar, not 100% decided).
I had some questions around heat dissipation and how I can calculate and avoid the thing over-heating.
Is there a…
David VK2VXK
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6
votes
1 answer
RX antenna and RTL SDR with upconverter ..How to hear something?
I mounted a small RX antenna (mini whip, bought from eBay) (on 10-th floor) and I want to try to listen to something. I bought a RTL-SDR with Upconverter which supports HF. RX antenna's operating range is 100kHz - 30Mhz.
If I want to listen…
kesrut
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6
votes
3 answers
Will coaxial cable degrade over time?
I have a 40' section of RG-8 that is about 35 years old. One end was terminated with a standard PL-259 and the other was soldered directly to an antenna.
When I removed the connector from the one end, the cable itself appeared pristine. The other…
Lance
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6
votes
4 answers
I am installing a ham radio and want to properly ground it
I am installing a ham radio and want to properly ground it.
I will be including a lightning arrester that will also go the the ground.
I will have a 20' mast with a long wire antenna running 130+ feet out to the south. The far end will be about 45…
Chris Baker
6
votes
2 answers
What are the default repeater offsets on 70cm in different countries?
I am looking for a reference list of the default repeater offsets by frequency and country on the 70cm band, to supply it into a radio control software. Most radios come with a list built-in, but the respective data is hard to collect.
There is an…
Georg DO1GL
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6
votes
3 answers
What is the easiest way to print data on qsl cards?
I confirm all QSOs via LOTW and eQSL but some people also request QSL cards via bureau or direct. Of course I don't want to disappoint them and I reply 100%.
But I find it such a burden to print sheets of labels and stick them on the cards. So I…
ON5MF Jurgen
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6
votes
3 answers
License upgrade doesn't extend term of license?
I just upgraded my license to Extra about a week and a half ago, so perhaps I'm supposed to know this. The FCC database shows my upgrade to Extra, but the expiration date and callsign haven't changed. I thought that my license would be renewed, at…
Rodney Price
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