Amateur Radio Stack Exchange
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1500 questions
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2 answers

Why are hand-wound coils so common if commercial inductors are available?

In most schematics of ham radio receivers and transmitters the inductor is mostly given specifically as the number of turns around some certain toroidal ferrite ring (for example). This corresponds to a certain inductance, which more often than not…
DK2AX
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RF Antenna - V pole - Should one leg go to ground and the other to signal?

I'm attempting to follow this white paper in order to build an antenna. This is my first antenna and as such I have a rather simple question. DIY 137 MHz APT Weather satellite antenna by Adam-9A4QV https://www.youtube.com/watch?v=9WNmhfpWxdk Should…
Cody Smith
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What is the best approach for measuring return loss of a home-made 3cm horn?

Let's assume I have built a SMA-to-waveguide transition that flares out into a horn antenna. There's no flange between transition and horn, it's made of a single metal sheet. The antenna has tuning screws, and my goal is to find the screw position…
mpb HB9EGM
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Is this the Correct Ferrite Core to Reduce RFI as a Common Mode Choke?

I have a Flex 3000 connected via RG-11 coax to a inverted V fan dipole tuned for 40m and 20m on my roof. I have an "ugly" balun up on the mast by the antenna. I further have the feed-line going into a lightning suppressor where the line enters into…
Etep - VE6ETP
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Dipole antenna radiation field equation

Can anybody provide me with an idealised formula that describes the radiation pattern of an omnidirectional dipole antenna? In particular I am interested in the formula that creates a plot similar to the following: Note: I am looking for a…
David
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Size of ground plane disk for vertical antennas?

I’m looking for information about the diameter of a ground plane disk that I can use with a regular car radio and car type antennas in my home. DIY would be best, or any other ideas for a antenna that will work. I have tried Google, but have found…
Gregory DeHart
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Does a parabolic reflector dish change circular polarity?

I've been receiving satellite signals in the L-band (~1.7GHz), recently. These signals are RHCP. So far, I've been using a DIY helical antenna in axial mode, and a patch antenna with cropped or clipped corners. My favorite tool to calculate the…
polemon
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Is a US Extra class exam from the '90s valid to upgrade from Advanced class today?

If one passed the Extra written test in the late '90s at an ARRL test center but did not get the 20wpm endorsement, yet is an Advanced operator, would they now be upgraded to Extra class or do they need to retest? As I stated, I passed the written…
Adam Albanowicz
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Can my laptop pick up CB radio frequencies?

I was on my laptop watching a show and I paused to look something up and since there was no sound I could hear a voice talking. It sounded distorted like it was coming over a radio and I couldn't make out what was saying. There does not appear to be…
Christian Castellanos
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Can this 960 MHz CelWave fiberglass antenna be retuned for the 70cm band?

I recently inherited a CelWave fiberglass antenna pictured below. It is marked that it's for 959.9875 MHz. The model number appears to be either 339 or 359. It is 96 1/2 inches from base to tip. I checked it on my MFJ Antenna Analyzer and found it…
Lance
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How do I have a full signal of noise on a handheld?

I'm new to ham (although I've had a license for a long time) and I'm having issues with receiving on a basic handheld. I have a cheap BaoFeng UV-82HP and I keep getting full signal noise at random times. I have gotten this on different channels in…
Eric Fossum
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Radial length for vertical antennas?

I plan on installing a vertical antenna soon. I expect it to cover from 80 meters to 10 (or perhaps 6). I plan on putting down 32 radials. I am wondering if 16 66' and 16 33' radials will be just as efficient for the higher bands as would having…
MarqTwine
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Do signals have to be more separated on higher frequencies?

Someone told me that 10 meters was the biggest band because you can fit the most channels in it. He said that in higher frequencies like 2 meter etc, you have to separate the signals more apart for them to work. Is this true? Can HF frequencies…
Skyler 440
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Do Loading Coils Supply "Missing Degrees" to Electrically Short Radiators?

References are made on this and other websites to the effect that loading coils can/will supply "missing degrees" to electrically short radiators. But do they?
Richard Fry
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What are the effects of different feed-line incidence angles?

Consider a dipole antenna fed by a coax (say, longer than the antenna) with a signal reasonably close to the dipole's resonant frequency. Various sources say that the feed-line should approach the antenna perpendicularly. What are the effects (SWR,…
hotpaw2
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