Amateur Radio Stack Exchange
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1500 questions
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2 answers

Is there a digital multimeter that is more interesting for a ham than a run-of-the-mill model?

My 22-years old Fluke 79 died on me today... Luckily, it was a quiet dead, but nonetheless it left me a bit emotional... So, I am in urgent need of a replacement digital multimeter. This made me wonder whether there would be a model around that is…
on4aa
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Noise & shielding, SDR Dongle

First, I'm very new to SDR. This may turn out to be really obvious. I just want to verify my thoughts before I spend more dollars. I have a USB dongle with the RT28xx in it. Works great. Side by side I have a 35 year old Azden 2 meter receiver. …
David Hoelzer
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Tuning/trimming a ground plane antenna

I've built a ground plane antenna with a 19.5" vertical and 4 20" radials. Currently, at 147.135 MHz my SWR is 3:1, clearly not ideal (and even bad for the transmitter!). I'm reluctant to start snipping radials because I really don't know if the…
David Hoelzer
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What is the reason/origin of conventional US repeater offsets?

In the US, the common (though not universal) repeater offsets are ±600 kHz in the 2m band and ±5 MHz in the 70cm band. How and why did these offsets come to be standard for amateur repeaters? The minimum simplex channel spacing is much less than…
ESV
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6
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1 answer

Video transmission between ATV and SSTV

I'd like to experiment with amateur video transmission in a setup halfway between ATV and SSTV. 480 lines of B&W image would be sufficient with 10 FPS, and I'm interested in both digital and analog methods. I'd prefer if I wouldn't have to buy new…
dnet
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Lightning Dissipators

I have heard about many lightning protection strategies in the shack, but nobody mentioned the lightning dissipator. The lightning dissipator consists of many small spikes and prevents a strike by slowly discharging through each little spike.…
Skyler 440
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What does the term 3 kHz deviation relate to in the FM world?

I am confused when someone says "your audio levels are set right and has good deviation at 3 kHz" when talking about wide-band 25 kHz FM signals. First confusion: Why are audio levels measured in kHz? I find it very misleading when you are…
Skyler 440
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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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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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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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Is it possible to transfer an area-specific call sign from a deceased relative?

I passed my Technician exam 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. From…
Some guy
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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
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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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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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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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