Amateur Radio Stack Exchange
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1500 questions
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What's the effect of directly connecting ladder line to coax?

I was watching a video where ladder line (450-ohm) was directly connected to coax (50-ohm) without a matching transformer. Mating your Coax to Ladder Line Wouldn't this mismatch make it impossible to achieve a 1:1 ratio back in the shack? What am I…
Dax
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Is the original satellite dish "ruined" when a slot antenna is cut into it?

A fun vertical antenna can be made by cutting a horizontal slot in a satellite dish, as documented in e.g. http://www.w6nbc.com/articles/2016-3QSTdishslot.pdf and discussed in How does a slot antenna work? and other questions here. But how would…
natevw - AF7TB
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Non-inductive resistors

When we use a "non-inductive resistor" to check the output impedance of say an unun, say 50ohm 1:1, what resistor type is actually non-inductive, or does it not really matter as long as the leads are short and frequency is low? I know there's…
t252
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Can I connect my station ground to my house's ground rod?

I'm setting up my first HF rig and I'm reading a lot of conflicting information regarding station grounding. Can I connect my HF rig/station's ground to my house's ground rod or do I need a stand-alone ground rod for my station? I was told I need…
SomeGuy1989
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When was the FCC Part 97 requirement for a time-out timer removed from repeaters under automatic control? Or, am I just nuts?

I've been remiss in keeping up with the changes in Part 97, especially in the area of repeater stations. A recent discussion about changing the time-out timer's period had me scurrying to the CFR, and lo, I could not see the requirement in the…
KenTenTen
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Eliminating RFI from raspberry pi

I am trying to eliminate RFI coming from a raspberry pi 4. The Rtlsdr(enclosed in a metal case) is directly plugged into the pi without any USB extension cable. The frequency of interest is at 1420.40575Mhz, few strong spikes that can be seen in the…
radastro
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Why am I hearing FM radio show content on 1.355 MHz? (Using CubicSDR and SDR kit)

I am just beginning to learn about SDR. I purchased a "NooElec NESDR Mini 2 SDR & DVB-T USB Stick (RTL2832 + R820T2) with Antenna and Remote Control" I plugged it into my Mac, downloaded CubicSDR, and was quickly able to listen to local FM radio…
Jack Amoratis
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Which way is a yagi polarized?

I am installing a yagi antenna that will receive signals from multiple omni antennas that are vertically polarized. Which way should the elements of the yagi point to match? Up and down, or horizontal? I must not be asking the question correctly to…
T3chie - Bitoku Labs
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Can I use new 14500 batteries instead of AA with Yaesu VX-8DR?

In addition to the proprietary battery, that came with my radio, I also purchased the part allowing usage of three AA-batteries. That was about 10 years ago, before the appearance (and wide availability) of the 14500 standard. Simply replacing AAs…
Mikhail T.
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How to calculate or estimate surface area of required ground plane for a mobile antenna?

I don't have conditions for installation of a fixed 2 m/70 cm antenna at home, so I'm thinking of using a mobile magnetically mounted antenna on a conductive plate instead. So my question is: What are the rules of thumb for getting ground plane…
AndrejaKo
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Antenna tuner at the transceiver output confusion

I am a bit confused. Let's take a HF transceiver for example. My understanding is that the output impedance of the transmitter is 50 ohms. The impedance of the coaxial cable feedline is 50 ohms, and if we have a resonant antenna at the operating…
Engineer999
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bizzare CW on 2m

I'm currently in Kershaw, SC. Yesterday an automated signal popped up on a 2m simplex freq (147.455 MHz) and has been running since. It sounds like Morse, but it is random letters that don't seem to have any repeating pattern. After every seeming CW…
Aaron
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How to meassure a ferrite using a VNA?

I want to measure a ferrite toroid using a VNA. I would like to classify it for a whole range of frequencies but if it's too complicated I'm OK to just pick one frequency. I have 3 questions actually: 1: Is there a preferred test jig? My plan is to…
Jack0220
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Do these look like amateur radio antennas?

I am planning to move into a new apartment, and of course would like to install a HF antenna there, on the roof if possible. Today I noticed a small Yagi antenna on the roof of the building , more than likely for VHF, but more interesting, seems to…
Engineer999
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Will a HF beam antenna on rooftop building interfere with other antennas there

I am moving into an apartment on the top floor of a building and I intend to install a HF beam antenna for 20 to 10 meters, on the rooftop of the building. I notice that there are already some antennas installed there on the rooftop. Possibly TV…
Engineer999
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