# All Questions

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4 views

### TCP/IP-based antenna controller for a UHF/VHF satellite ground station

I am looking for an antenna rotor controller with a TCP/IP interface. Most rotor controllers (like the ones for YAESU series) are either serial or USB-based. I was wondering if there are alternatives ...
27 views

### Is this author correct about using a λ/2 of wire for a coil to get the proper delay on a λ/2 collinear antenna?

Is this author correct about using a λ/2 of wire for a coil to get the proper delay on a λ/2 collinear antenna? Improving the Super-J August 5, 2012 by John S. Huggins I agree with him that there has ...
13 views

### Improving Vara HF speeds

I'm using Winlink with a laptop hooked up to an IC-7300. The registered version of Vara theoretically supports speeds up to 8,500 bps, but I'm seeing speeds more like 700 bpm. Is there anything I can ...
24 views

### UV-5R High Gain Antenna Performance

My Baofeng UV-5R came with a shorter 6.5” antenna and a “high gain” 15.3” RH-771 antenna. In your experience, how much of a difference in range does the use of the longer antenna achieve?
59 views

### Why does beamforming bring more power to the received desired signal?

Consider a normal array model with $N$ element. The output of the array is given by, $$y=w^Has$$ where $s\in\mathbb{C}^{1\times T}$ is the desired signal ($T$ is the number of snapshots and the power ...
33 views

### Baofeng UV-5R Scanning with Noisy Channel

I just bought a Baofeng UV-5R. I programmed in some channels and have been scanning these channels for activity. I have had a situation come up on a few occasions where there is some activity on a ...
48 views

### How do hardware CW tutors work?

I'm beginning to learn CW. Stumbled upon hardware tutor devices: this or this. Can't understand how the tutor mode works... the manual says it plays out random number/letters/callsigns etc, but there'...
49 views

### Grounding a vertical antenna from a balcony

I have a multiband vertical antenna mounted onto the railings of my balcony apartment high up on the 6th floor of an apartment building. The antenna is not grounded. This antenna comes without radials....
530 views

### Why am I not hearing repeater identification more often?

I just bought a 2m/70cm handheld. I programmed in the local repeaters and have been scanning them for a couple of days. Only about twice have I heard one of the repeaters come up and identify itself. ...
20 views

### How to analyse the distribution of the noise being received by my RTL-SDR device?

I'm very new to RTL-SDR and signal processing in general, but have managed to get my device (NOOELEC NESDR Mini) working and data into Python (via the pyRTLSDR library). I am able to output a complex-...
26 views

### Looking for a model or description of an EME channel

I am looking for any technical/scientifical/specialized reference describing in some detail the moonbounce for VHF/low UHF frequencies. More precisely, I would be interested in a paper or publication ...
2k views

### Why are an antenna’s nulls sharper than its lobes?

Why, for realistic directional antennas, are its nulls sharper (deeper, narrower, etc.), than the radiation pattern’s lobes (local angular maxima)? Is there some physics or mathematical geometry to ...
69 views

### Non line of sight long range wifi [closed]

I have a situation where I'd like to get a network signal from my house to the end of my driveway for security cameras and the like. My driveway is long (about 1km). Its also non line of sight from my ...
32 views

### Troubleshooting range on Lora Radio

I am using these Adafruit LoRa radio microcontrollers: M0 radio paired with these parts to make up the antenna system: antenna connector cable And for some reason I am unable to get much further than ...
36 views

Can I use sub-ghz (433 Mhz) to transmit audio.I already used radiohead library with RFM96 to transmit small packets of data and built a point to point mesh chat application. Now i wanted to test FSK ...
37 views

### How to check second-hand ICOM IC-718?

I’m buying a used IC-718 from a local ham. I can verify its function before I decide to buy. I’ve read the manual and know the functions and capabilities. What should I check / look for, apart from ...
25 views

### Recommendations for Antennas installation with Steep slopes

I have a property that I am trying to figure out the right antenna setup for. Currently running the following Antennas: 1x Hustler 5BTV Vertical with radials 1x Chameleon in a NVIS configuration 1x ...
53 views

### Is 6 kHz bandpass filter wide enough for listening to SW broadcasts?

I'm considering buying ICOM IC-718 as a main rig and also to use it for SWL. Read contrasting opinions on the Internet, with an article reviewing dedicated SW receivers saying "That receiver's ...
63 views

### How does change in dipole angle orientation affects mutual coupling in an antenna array

For dipole antennas in an array system, for any configuration of the dipoles, how does change angle of orientation in one or more of the dipoles affect the mutual coupling between them. Is there a ...
292 views

### Can coax be run through the center of a radiating element without currents being induced on the coax shield?

I run a λ/2 vertical dipole for 20M that's fed to a 1.5:1 balun at its center with coax that is perpendicular to the dipole (parallel to the ground), for about 30 feet before it comes down to the ...
110 views

### Does anyone know of a compact ELF wave transmit antenna I can buy or make?

I need to transmit frequencies as low as 1Hz and I know the wavelength is the speed of light but wondered if there has been any breakthroughs in this field? I need a handheld antenna or at least one ...
58 views

### BF-888 radios don't work with UV-5Rs on the same frequency

I play airsoft here in Quebec Canada, and I have 2 Baofeng BF-888s that I got a few years back. Now people are mostly using UV-5Rs. I used CHIRP to program my radio to the same frequency used by the ...
136 views

### I'm looking for an effective beam antenna for both 20 meters and 10 meters

My favorite HF bands are 20 meters and 10 meters. I am currently using a multiband vertical antenna, but really it's not so great for DX'ing. I am looking for a good upgrade. I'm still learning alot ...
65 views

I got an anytone 778uv that I want to add to my car. I'm looking at adding it with a add a fuse to an open fuse slot, however I see many people just saying to add it to a chassis bolt. I am new to ...
311 views

### What gauge of winding wire will be “invisible” but sturdy as an antenna?

I plan to build a receive-only longwire/Beverage antenna. The wire will be at least 40m/120' long and strewn at about 7m/21' above ground. Tried "regular" thin insulated wire but it was an ...
68 views

### How to understand same SWR but different Tx/Reflected power

I'm tuning a wire dipole. Cross-needle SWR meter shows the same SWR on the lower end of the band as on the higher end. However, the needles move much higher on the lower end. They cross on the same ...
30 views

### How do I send a raw CI-V command via rigctl?

With my ICom 9700 the CI-V reference manual says that I should be able to send the command 0x07, subcommand 0xD0, to select the Main band, and 0xD1 to select the Sub band. subcommend 0xB0 to exchange ...
94 views

I just got 4 BF-F8HP radios, 2 knockoffs, and 2 "legits"; definitions of knockoff and legit come from a website I found. All 4 of them are having this issue. I can transmit fine on both 2m ...
87 views

### Is there such thing as a center-fed longwire?

I want to make a longwire/Beverage receive antenna that will work on a wide range of bands (80-10m or wider). I've got a place where I can put a wire of at least 50m/150'. The only problem is — the ...
84 views

### Can I use electrical ground / earth as my RF ground?

I live on a high floor in an apartment block and have a radial-free multi-band vertical antenna attached to my terrace railing. This is the antenna : https://www.thunderpole.co.uk/amateur-radio-...
43 views

### Generally speaking what might one expect from a J-pole based on PVC covered in tinned braid? [closed]

Would the skin effect provide benefits or would capacitance/inductance cause problems?
193 views

### How to take to account impedance mismatch losses when cascading 2-port networks as RF System?

I'm trying to learn how to correctly calculate (cascade==RF system cascading) the connection of 2-port networks, taking into account mismatch losses. For example There is a first 2-port network, its S ...
41 views

### Should I expect to just start hearing stuff when I connect to an EchoLink conference server?

I've installed EchoLink on my Windows machine and on my iPhone, and EchoHam on my Mac. At the moment, I have the TCP 5200 outbound allowed from any device on my LAN and UDP 5198-5199 forwarding to my ...
28 views

### Diagnosing IC-7100 Drive Amp Bias | PA Won't TX

A faulty in vehicle DCDC charger has fed 16V or so into my brand new IC7100, killing the main board and preventing it from transmitting. I've replaced the mainboard with a brand new one however I'm ...
16 views

### Map APRS data on Windows laptop using Kenwood D710's internal TNC

My D710G has APRS built in. How can I get that data displayed on a laptop?
29 views

### Titan antenna VSWR and radio problem

I just installed a new Titan DX antenna and I am using psk31 with fldigi. When I transmit on 20m at 14072, the SWR is 1.65 and it shuts off my computer and the radio keeps transmitting. However, on ...
29 views

### Feeding APRS data into GR Level 3

Our Skywarn group is looking for a way to feed the positions of our spotters (reported via APRS) to into GRLevel3 to be displayed on the map. Does anyone know of a tool for doing this, or ...
35 views

### Vara FM winlink with Kenwood D710g and DRA-50

I'm trying to get this working for the first time on a vhf/uhf radio. PTT is working and it seems to be transmitting, but neither I nor the program can hear any response. I' ve tuned the radio to the ...
38 views

### One cable two different radios

I have a GMRS radio and VHF/UHF radio in car. I have an antenna mount and cable installed. I install appropriate antenna for the radio in use and manually remove and attach cable to matching radio. It’...
56 views

### Understanding low MUF in VOACAP

I've started playing with VOACAP to better plan and predict conditions on 27 MHz (CB). To my utter astonishment, VOACAP says that I won't be able to communicate on that frequency, regardless of ...
126 views

### CHIRP on Mac in 2021

Has anybody had success in running CHIRP on a modern Mac? I am running OSX 10.15.7 and the download I found for Mac looks like just source code, no app file at all. I'm considering trying a build from ...
100 views

### MF band mixer - feasible parameters

Trying to build an homebrew receiver for MF band broadcast (Navtext). Usually working on VHF, where all parts are easily found as an IC, but here I'm trying to get back to roots, so I may be missing ...
63 views

### Is it possible to set a precise frequency with a Btech 50x3 or am I stuck with being off frequency all the time?

I can't seem to figure out how to set it to the simplex frequency, 146.520. Always skips to 146.525 or 146.500.
57 views

How do you measure the two to one bandwidth of an antenna using a Bird Watt meter? Tom Planer KJ9P
93 views

### Can ham radio antennas interfere with RING devices, causing them to produce high-pitched noise? [closed]

Can a HUGE ham radio antenna on a house with an array of RING devices (5 in total) cause interference and high-frequency reverberation? The attached shows one of these devices (there's 2 under the ...
143 views

### Hardened UHF Antennas

Minuteman missile silos used an interesting hardened UHF antenna. What kind of antenna is this? Does anyone have a drawing with a cross section? Edit: Jay Moore added a picture to a different type of ...
44 views

### What are the unintentional radiation limits in U.S. HF bands?

What are the radiation limits in U.S. HF bands in terms, not in terms of uV/M, but in dBm or uV levels transmitted though an HF dipole antenna? I assume that if the antenna is connected to a receiver ...
85 views

Romanian amateur radio license Hello. I am wondering how to get a amateur license in Romania, and whether there is any material on this. I am licensed in the US, am a Romanian citizen, and can speak ...