# All Questions

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111 views

### Is a balun really necessary for a small loop antenna?

I am in the process of designing a small receiving loop antenna for the lower HF bands. By small I mean a circumference of less than $0.2\lambda$. Thus, a uniform current distribution can rightly be ...
129 views

### Grounding for lightning safety - upper floor (UHF/microwave antennas)

I have some UHF, microwave antennas and an antenna rotator on a roof mounted mast. The "radio room" is in the second floor just below the antennas. Also the service entrance for building electricity ...
81 views

### Bias Tee for HF: noise and losses?

I have a homebrew remote antenna switch. It uses relays and it has a nRF24L01-based wireless link to the band selector (Arduino, taps into CAT and switches antennas accordingly). I would like to ...
169 views

### Can half of a directional antenna (Yagi-Uda, HB9CV) be replaced by a ground plane?

Consider a center-fed dipole antenna. It‘s well understood how the bottom element can be replaced by a ground plane (in practice, generally a few rods but in principle a conducting plate would work as ...
42 views

### Problem of two SAW fitler?

When I series two SAW filter, why the attenuation less than sum both of them in stop band region. Each of them (in stop band) have 60dB attenuation but when series them, the attenuation is equal to ...
180 views

### how does this collinear antenna work?

I was looking for a cheap and easy to build 2M/70cm vertical. I found this: http://vk2zoi.com/articles/dual-band-high-gain-flower-pot/ Here are the plans to build it: But I don't really understand ...
60 views

### How do I get my Windows 10 PC to consistently recognize my RigExpert AA-35 ZOOM?

I have connected my brand new RigExpert AA-35 to my Windows 10 PC via the provided USB cable, but the AA-35 does not show up in Device Manager. There is no COM port assigned to it, nor does it show ...
158 views

### How do I tune my EFHW 40-10 to have the lowest SWR in the 40, 20 and 15 meter bands?

This is a reading from my RigExpert AA-35 ZOOM of my EFHW 40-10 inverted L with radials, and feedpoint 2 feet above the ground. Any thoughts as to how I can tune or move this antenna to get the ...
99 views

### Is the Alinco DJMD5 illegal for ham use?

I am quite interested in buying the Alinco DJMD5TGP as it seems like a full-featured radio for a low price. And I have already started studying for my Technician license so I can transmit. And then I ...
7k views

### Are Baofeng radios illegal in the U.S?

Having a low price budget, my search for my first ham radio to buy has led me towards Baofeng. A quick Google search on baofeng showed a lot of results that said that certain model baofeng handhelds ...
838 views

### Why is my diplexer such a spectacular failure?

I'm trying to create a diplexer for the 2m and 70cm bands so that two antennas can share a feedline to my "shack". My radio is a Yaesu FT60 handheld, 5W max. I have home made a j-pole for 2m, and a ...
49 views

### Podcasts for Technician Test

Is there a podcast to listen to that teaches in-depth the technician class questions? All I could find is podcasts that just read the questions and answers. Is there a podcast that goes in-depth to ...
142 views

### What does an antenna analyzer tell me about these coaxial cables?

Note: more measurements added after graphs below I recently acquired a RigExpert antenna analyzer and I am trying to learn how to use it to test cables. I took two cables to start with to try and ...
179 views

### How do you find a test location?

I'm new to ham and I'm wondering how to find test locations/study guides. I heard about this from a friend.
150 views

### Can a ham radio pickup police signals?

Can you pick up police signals with ham radio? Secondly, are you able to contact emergency services with ham radio. For example: In the middle of a hurricane, with no power, can you technically use a ...
3k views

### Can you use a satellite dish for a ham radio antenna?

Can I use a satellite dish as a ham radio antenna? I was thinking that because there are two unused, working satellite dishes that have all appropriate wires attached conveniently to the roof of my ...
76 views

### Transmitting Callsigns

I started learning for my technician test and I noticed one of the FCC guidelines is that you have to Transmit your callsign at the beginning of radio contact, and every 10 minutes How does ...
167 views

### Ham Radio and Space Communications

I hear a lot of people talking about getting in contact with space with their ham radio. What do you hear? Do you talk to astronauts? Or: Is it just an expression?
68 views

### Setting up an Outdoor Antenna

If I would buy a ham radio with an outdoor antenna, what would I need to do to make it work (e.g can I just stick it outside) especially because I live in Miami and Miami doesn't exactly have the best ...
164 views

### Space Requirements

As I progress in my path to getting a ham license I notice that a lot of radio enthusiasts avidly talk about their radio shacks (or do they call it cabins?). Do I need that much space to start? Do I ...
96 views

### What does a License look like?

What does the HAM license look like? Is it a card? A document? All I could find on google is ham radio license plates.
3k views

### Can a ham license be used for a job?

If you get a ham license, can you, later on, get a job with that license, or at least display it on a resume? Or are there further licenses after ham radio licenses?
79 views

### Equipment Pricing

I am wondering about the exact pricing of kits. What is the range of each radio? How long do they last? Should I buy a portable or not? My complete budget is \$100.
69 views

### Glass Block Pass Through

In my future shack I will have glass block windows consisting of 6 x 8 blocks and a 6 x 16 vent. I've been searching, but cannot find the best solution to pass coax through the windows. I've thought ...
267 views

### Getting Started In Ham Radio

I'm 13 years old. I hear all the fuss about ham radio how awesome it is. I really want to join, but I hear you have to get a certification. How much does it cost? How long does it take? How much does ...
123 views

### Why is a separate repeater required for digital modes? Why can't an analog repeater be used for digital modes?

Regardless of the mode: digital or analog, the radios always transmit sinusoidal EM waves. So wouldn't a regular analog repeater be able to rebroadcast that EM signal regardless of its encoding?
872 views

currently I am involved in a project were a data link is needed to communicate different devices. This is in one to many configuration and the devices are stand alone. For this project there is need ...
87 views

### Are there restrictions placed on transmissions in licensed spectrum in the United States?

If I obtain a license to a chunk of spectrum, are there any limitations on what I can do in that spectrum? For example, would I need to declare to the FCC my intentions for using the spectrum (e.g. ...
111 views

### Why can't we use a simple wire for receiving 2.4 GHz signals?

I wanted to build a small drone of my own as a hobby project. My old drones were broken so I wanted to salvage as much as I could to build a small indoor one. I wanted to use an Arduino, however, I am ...
91 views

### What is the format of Yaesu FT3D's QSOPCTDIR.dat and QSOPCTFAT.dat files?

The Yaesu FT3D can send photos, but only if taken with the optional external mic that has a camera. I want to be able to send photos that come from elsewhere, by putting them on the SD card. But it ...
47 views

### Modeling a multiband Yagi in 4NEC2?

I tried to model a multiband yagi. I added radiators for 10-15-20M, and reflectors spaced .15 wavelenghts away. This gave a nice result with three sharp dips in SWR in the 10-15-20M center frequencies....
154 views

### Can one repeater be used to hit another repeater?

Here's why I wonder about this: I would love to be able to reach an Echolink-enabled repeater or similar, but I live on the other side of a ridge that would probably block a transmission to the ...
90 views

### Method to generate PIM

I would like to have a go at measuring PIM. ( Passive Intermodulation ) in UHF. To test my ability to measure PIM, I need to find something that generates PIM. I either envision a 50Ω device that ...
246 views

### Designing a helical antenna for a dish

I'm interested in a dish antenna with an axial mode helical feed for receiving video. My target frequency is about 1280 MHz or the 1.2/1.3GHz range. I've been able to figure out helical basics, like ...
121 views

### Relation between antenna physical size and gain

I would like to know whether increasing the size of the antenna help increase its gain. Does this hold only for certain kinds of antennas like parabolic or horn antennas? And if it is true, can you ...
129 views

### Can I use a 1/4 wave decoupling stub to enable mounting of a vertical yagi on a metal pole?

My understanding is that the ground plane radials used on, for example, a free standing 5/8 wave 10 m vertical antenna mounted on a metal pole, are actually 1/4 wave length decoupling stubs, the ...
194 views

### Can I splice a random wire antenna?

I have an Icom AH-4 with a random wire antenna. I have a fence around my property that is 60 feet long by 70 feet wide. The outdoor tuner is placed at the begining of the 60 foot section which leads ...
283 views

### Need batteries for backpack operation

I am building an HF backpack rig using an Icom IC-706MkIIG with a Opek HVT-400B antenna. The specifications on the radio say 20 A draw at high power, so what size and type batteries would be suitable ...
109 views

### Problem with theory of HF detector

I'm currently trying to build my own SWR power Meter. This design is based on the so known HT detector with schottky diode BAS70. For my understanding, and for easy purpose, I'm currently focusing on ...
387 views

### How can quadrature mixing adjust the phase of all frequencies by the same amount? Can it be done in the digital domain?

This came up in some feedback I got when I tried to answer What is IQ in the context of SDRs? and revealed some of my own misunderstanding. Initially, I gave an answer something like (paraphrasing): ...
32 views

### Problem with mAT30 ATU and FT-450D transceiver

Does this tuner work with this transceiver? Would appreciate response as I cannot get it to work!
86 views

### Why do some 1/2 wave collinear designs have a 1/4 wave element?

I think I understand the basic principles of a collinear antenna. How the Coaxial Collinear Antenna Works? seems to describe it well. However, I've just repaired a 1090MHz (ADS-B receive only) ...
90 views

### Receiving and decoding RDS in GnuRadio

I'm new in radio, so I started with seemingly easy task - receive and decode RDS data. I use GnuRadio to understand the concept of working with RF signals. So according to standard RDS receiver looks ...
188 views

### Problem with RTL-SDR v3 dongle - unusable PLL

I own an RTL-SDR v3 USB dongle (official version from rtl-sdr.com). I've successfully used it for decoding weather satellites past year. I use (GQRX + Audacity)/(Arch Linux 64bit) + (WXtoIMG)/(Windows ...
25 views

### Baofeng UV5RA charger station error

I recently bought 2 Baofeng UV5RAs from the same vendor. Neither of the charging stations work. They both flash green/red immediately upon plugging them in--before any battery is seated! When I seat ...
55 views

### Would a phase compensated sinusoidally spaced folded dipole present less noise to a receiver?

I am attempting to design an antenna similar to a TTFD, double zepp or array of end fed wires, with a sinusoidal, with the period of the wavelength, spacing that causes additive waves on the target ...
163 views

### Repeater Features: What is e-power and link?

I am so new to ham radio that I don't even have a transceiver or a certification study unit yet. Just learning all I can right now. So, I'm looking at a repeater that I might be able to reach with a 5-...
171 views

### LSB modulation and demodulation

A USB signal is basically a baseband signal shifted up in frequency. However, an LSB signal is the mirror image of a baseband signal then shifted up in frequency. How is this 'mirroring' modulation ...