# All Questions

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1 vote
11 views

### What lengths of counterpoise is suitable to support a 58 foot "random wire" antenna?

I am a technician interested in building my first antenna. I want to explore HF bands, 160m - 6m. Quick impedance calculations indicate that a 58 ft "random wire" antenna could work for this....
• 111
14 views

I am currently working on project which utilizes RTL-SDR for capturing packets. I know that those packets are whitened with x^9 + x^5 + 1 polynomial. No matter what I do the descrambling each time ...
1 vote
34 views

### Feedpoints for stacked antennas?

I'm considering building some stacked 70cm quad antennas (home brew / DIY build) -- and... I'm having a devil of a time trying to figure out how/where to feed these antennas. For a single home-brew ...
• 11
1 vote
51 views

Would it be legal to play a multiplayer video game over a ham radio link? Both players are hams, and their call signs will be transmitted in the link.
• 271
15 views

### What is the best monoband VHF HT 2 Meter Antenna [closed]

I'm looking for the best VHF monoband antenna for my handheld (ICOM IC-V86). My goal is to significantly increase my talking distance. I would prefer a flexible antenna over a telescoping antenna if ...
• 1
46 views

### Understanding Coax Impedance when Connected to Reactive Load

The 50 ohm characteristic impedance of my coax is only "characteristic" if it's terminated with $50 + 0j$ load. So when the coax is connected to an antenna that is fairly reactive like \$ 23-...
• 261
1k views

### Putting up a tower on my residential property

I live in upstate South Carolina. I contacted the city and the person who answered the phone call said it would be a new structure and can't be higher the the house on the property. I looked at the ...
• 31
68 views

### Extend transmit range of my HT

Based on comments and new information I have rewritten this question entirely: I need advice on a simple, inexpensive, and non invasive (no holes being drilled in walls) way to talk to repeaters in my ...
• 23
49 views

### What are the qualities of a good field day site?

What are the qualities of a good field day site? Specifically what do you or your clubs look for or use as criteria for site selection?
• 123
206 views

### DIY Short Vertical Wire Loaded Antenna: Using 20 Ohm Resister to Widen Q

I've been working with Xnec2c to model a 40 meter vertical antenna I want to build for field QRP. This antenna is short at 25 feet and uses a 1:1 unun at the base with 4 radials. The model has the ...
• 261
61 views

### Is there a list of public datacasts?

I know several datacasts which are free to almost free to receive. Like there is the outer(other-)net, which can be received using a lora module - it contains a subset of APRS messages and weather ...
61 views

### Can the 902-928MHz ISM band be used in Kazakhstan?

My team is planning to test an IoT sensor in Kazakhstan. This sensor normally sends data to an Edge device (a tablet PC) using the ISM radio band ranging from 902 to 928MHz. Is this band allowed in ...
• 103
29 views

I have recently had access to two SDRs a hackrf and a Plutosdr through my university.I am now trying to experiment and learn more about wireless communications and how to implement some examples on an ...
69 views

### Is a club call sign with a suffix (i.e. /GOTA) permissible for a Field Day GOTA station?

The 2017 Field Day GOTA Station FAQ states "The GOTA station uses a callsign different from the call used by the group’s main Field Day operation. The GOTA station must use the same, single ...
1 vote
67 views

### What is the name of this connector?

It's the TTL connector on an MFJ-1270. The pins are 1/10" spacing, but I don't know what it's called so I can order another one.
• 847
1 vote
66 views

### Link budget validation for a UHF satellite ground station

I built a UHF satellite ground station. It has a yagi with G=16.1dBi and an LNA with G=20.1dB. It’s a 430 - 450 LNA with NF=0.68. The RF cable, rg174/u has I think close to a 1dB/m, which would mean ...
46 views

### What is the type of Data Stored on GNU Radio File Sink

I am working on storing the data transmitted by AM Transmitter using GNU Radio. I used file sink to do that I'm here by attaching block diagram. So, I want to know what type of data is stored in file ...
59 views

### Identify format of the files with ".cap" extension [closed]

I have recently inherited a ham radio, and with it several IQ files with ".cap" file extension. They have "IQ capture" in the name. What formats might I be looking at and what ...
102 views

### Why is analog TV vestigal side band and not SSB?

Analog TV signals have one sideband cut off to reduce their (very wide) bandwidth and save frequency space in the ether. The lower sideband is cut off, but not completely, the lower 1.25 MHz is kept ...
• 385
49 views

### New Amateur Radio User - UK

I am new to this hobby and was wondering if anyone could point me to some easy to digest beginner friendly materials that are relevant to the UK (A lot of my searching has returned US specific ...
1 vote
103 views

### Would a transmitter similar to "The Thing" be legal on ham bands in the US?

The Thing was a listening device used by the Soviet Union to eavesdrop on US government officials. It was basically an AM transmitter if I understand correctly, but it required another transmitter on ...
• 271
1 vote
16 views

### RigExpert AntScope2 is missing Data popup

I recently started using AntScope2 and everything was great. But all of a sudden the Data popup has disappeared. The missing popup is circled in the photo. How do I turn it back on or get it back? ...
159 views

### Can an 'ugly balun' be too long?

Will an ugly balun exhibit adverse effects if more coax is wound onto it than the recommended 18 - 21 feet? The antenna in this instance is a 40 Meter Delta Mono Loop that suggests using 22'-6" ...
• 187
90 views

### Is an Icom radio’s model ID info available via a CI-V command?

I have built a prototype device using an Arduino Nano Every which communicates (using CI-V commands) with Icom radios, to augment control of them. Currently I use the default addresses of the “target ...
86 views

### Digital Protocols, Public Documentation, and Encoded Messages

When is a new digital protocol considered "documented publicly" enough to be used for amateur radio transmissions? Part 97 states the following about prohibited communications: (a) No ...
95 views

### Do changing sidebands have their own sidebands?

An amplitude changing carrier wave causes sidebands to appear next to it when viewed in the frequency domain. But if those sidebands themselves also change with time (because the modulating signal is ...
• 385
81 views

### Using PVC coated solid-core wire for a small number of turns on toroid

I'm researching making my own 49:1 unun using an appropriate mix ferrite toroid and some reasonable gauge solid-core wire. (This is for an experimental HF end-fed antenna, though this detail probably ...
• 1,417
1 vote
50 views

### What is the point of using LNA if the SDR can increase the gain itself [duplicate]

Usually there is a LNA next to antenna, while SDR devices also have gain setting so we can increase the gain. As i know LNAs are amplifying all signals with same gain (Am I right?) So i wonder what is ...
• 133
74 views

### RF switch for half-duplex sequencing on amateur UHF satellite ground station

I need a 3-port RF switch illustrated below. The idea is to use this switch with a sequencer to enable half-duplex communication on a UHF antenna. The switch has three ports: port A connected to the ...
29 views

### Is there a console client for spyserver?

I am currently using multifm to monitor a few frequencies in the ISM band with a RTL-SDR dongle. I can pipe the resulting demodulated data to other tools. This works well enough, with a few ...
• 276
1 vote
69 views

### What band did walkie-talkies use in Europe before PMR446 was allocated?

The PMR446 band, now used for walkie talkies in Europe, was only allocated after 1997. I'm sure walkie talkies existed before that. What radio bands did those use?
• 385
111 views

### Understanding Impedance (R+jx)

In a typical antenna (lets say dipole for this discussion), the pattern below is observed in the impedance (R+jx) graph: I'm trying to wrap my head around this graph. Why does the resistance spike, ...
• 637
93 views

### Major 2.4GHz interference disrupting communications

I need help to determine what is causing significant interference with my communication devices, such as Bluetooth, router, and phone calls. I always use a Bluetooth headset when I'm on the phone. I ...
44 views

### Fox & Hound or regular FT8 for ARRL International Digital Contest?

So I'm thinking about casually working the ARRL Int'l Digital contest this weekend to try to pick up (hopefully they'll confirm!) a couple of new DCXX entities so I can get my DXCC (almost there). ...
1 vote
74 views

### How is it possible for a halfwave dipole antenna to be resonant?

I've been learning about antennas recently and I have some questions about the halfwave dipole antenna. My first question is about its resonance; as I understand it everything that oscillates has a ...
• 113
41 views

### Yaesu FT817ND + (Bluetooth) CAT control + ESP32 microcontroller: reading SWR "programmatically"?

I am building a wireless control system for a magnetic loop antenna. The system uses an ESP32 microcontroller (that has Bluetooth and WiFi) that automatically drives the magloop capacitor by means of ...
• 31
253 views

I've been thinking about building a VHF antenna using stainless threaded rod for the ground plane's radials to mate with a hub I already have. My theory is that will make life easier than trying to ...
• 1,657
65 views

### Any way to get LOTW "credit" for a paper QSL card?

I have some QSOs with hams who will send paper QSL cards but do not use LOTW. I know that if I manage to get a paper card from them I can submit it to ARRL for DXCC credit. But will that QSL show up ...
2k views

### Can I use speaker wire as a transmission line?

Speaker wire is really cheap and available everywhere, and it doesn't seem that different to 300 ohm twin lead. It seems to me it would make an excellent balanced transmission line. What would the ...
• 3,409
1 vote
70 views

### Is this amount of loss normal with LMR400?

I have a run of about 150 feet of LMR400 (specifically, it's this DX Engineering "400MAX" product). It connects to an Ed Fong antenna (2m, 1.25m, 70cm tri-band J-Pole) about 75 feet up a ...
• 300
92 views

### Linux Alternative Time Sync-ing for JS8 or FT8

I was learning about the time drift set and correct features of JS8Call and wondering about an alternative. Assume I have a wrist watch that loses 1 second a month and that it's been sync-ed to an NTP ...
• 261
82 views

### 14dB insertion loss for bandpass filter acceptable?

I'm busy with a direct conversion receiver for the 20m band, using a VXO and a 14.060 MHz crystal. I designed a bandpass filter with the following components, using this design calculator. Someone ...
1 vote
206 views

### Why do ham radio operators refer to current flow on the outside of coax as common mode current?

My understanding is that the desired mode of operation for a two wire transmission line is differential, where at any point along the line the addition of the voltage or current is zero, such that the ...
• 3,409
1 vote
89 views

### Baofeng Orange Transmit light comes on by itself (triggered by sound)

I have a BTech UV-5X3 and if I yell or blow into the mic, the transmit lights (red indicator light and orange backlight) come on as though I'm hitting the PTT button. Is this normal and am I actually ...
132 views

### Is an off-center fed dipole (and/or doublet) inherently unbalanced?

Does a balun/choke have to "work harder" in an off-center fed dipole than when the feedpoint is at the center? Or do the standing waves that develop keep the antenna balanced electrically ...
• 6,007
351 views

### Help on identifying signal type and extract audio from a signal

I Just recorded a signal using SDR++ and RTL-SDR. The signal seems to be normal audio but I cannot extract clear audio from it. I can recognize speech and tones even without any demodulation so I ...
• 133
1 vote
116 views

### How to best ditch the counterpoise of a random wire antenna?

The "ground" has several effects on antennas, most of them negative (see e.g. Why does an HF "monopole" need dozens and dozens of radials while a VHF/UHF "ground plane" ...
• 6,007
101 views

### Why does an HF "monopole" need dozens and dozens of radials while a VHF/UHF "ground plane" antenna only needs four?

It's a bit counter-intuitive that for an HF vertical antenna (such as a quarter wave monopole) the best advice is to put as many radials and as close to the proper length as possible. The typical VHF/...
• 6,007
34 views

### HAMRS logging app dumped all data

Anyone have this issue. HAMRS logging app on Android dumped 3 months of logs. It's an amateur radio logging app where you log your contacts. I went to open the app the other day and my profile and all ...