All Questions

This excellent answer to First Ham Radio contact from space; what frequency, what kind of antenna, and how did they route the coax out the window? in Space Exploration SE contains the block-quoted ...

I'm building a low-power shack to operate on non-licensed bands (UHF PMR 0.5W + HF CB 4W). I don't have any "RF-grade" sources of 12(-ish) volts and don't want to buy a specialised power ...

I've had my general class license for 20 years. I never progressed farther. This was back when you had to learn morse code at 13 WPM for General. I'm just curious what the procedures are to upgrade ...

I'm trying to build a transponder ramp test for mode c and s of aircrafts for my degree. I have a problem, I didn't understand reply system of transponde, how can I doba reply of a signal to test one?

I've programmed both my UV-5RA and FT-4XR via CHIRP and it has generally worked fine. However, one thing I'm not understanding is why it is refusing to program some stations from RepeaterBook input ...

What happens when a groundplane antenna's vertical element, bottom feedpoint, and/or bottom loading coil move down and encroach into the area below the plane formed by its own perpendicular elevated ...

Looking for suggestions for a portable antenna for use with a SDRPlay RSP1A. I notice that most other SDRs come with a few antennas, but not the RSP1A. I have a 2m/70cm HT, so I own a Nagoya NA-771R ...

Assuming a rhombic antenna is: terminated for directionality electrically isolated at its mount point mounted to a metal mast partway up vs top of mast horizontally oriented (elements parallel to ...

I've heard that in the early spark-gap wireless telegraphy era people would use kites with a wire acting as antennas and if the receiving side had a wire length that was an even division or multiple ...

I'm trying to experimentally investigate the radiation resistance of a v-shaped antenna. When it's fully unfolded and the reactance is at resonance, the resistance is about 73Ω. When it's folded, it ...

This a follow up from this question: QRN: How to chase down a solid S9 noise floor on 40m only Focusing on how to interpret the signals received with an electrically small, untuned "shielded loop&...

I picked up a used Katsumi Elekey EK-150 (manual) electronic keyer. I'm trying to get it working with my Kenwood TS-570S (manual), which has a 3.5mm Key jack. With a male-male audio cable connected to ...

I saw an interesting assertion recently, that resonant antennas are more efficient because they provide a better impedance match to free space at the resonant frequency. I believe that to be untrue, ...

I have a QRP rig (Mountain Topper) and a variable capacitor QRP end fed half wave antenna with an SWR LED indicator. The LED doesn't go fully out in all configurations but there is always a local ...

I have a TV antenna on the top of my house that I don't use. It is the highest point around so I would like to hang a wire antenna (for HF) on it. Is an inactive antenna going to cause any ...

It seems that a lot of cheap ASK transmitters (for remote controls, etc.) use a similar line encoding, an example can be seen here: Reverse Engineering a wireless doorbell and performing a replay ...

I am seeking the parameter used with the LTEXT buffer parsed from GPSTEXT $GPGGA. I have poured over a myriad of information without success. The LTEXT must take an argument, otherwise LOC E will ...

I've been trying to understand how dipole antennas work, and I believe I understand the basics when they're fed via a balanced feed line. In fact, every dipole physics YouTube video and web page I can ...

In many youtube videos about building low power radio transmeters , I have seen a piece of regular wire or extension cord used as a antenna. But , it seems like telecommunication antennas have ...

As a bit of curiosity, I was wondering what the longest path ever used by amateur radio operators has been. Of course the opposite side of the Earth is no problem with a good HF station. And you can ...

I'm learning about shortwave listening. I want to listen to amateur/ham radio on a portable radio (eg a XHDATA d-808) with ssb, I hear ssb is the main place hams would be on. I know it's hard to give ...

This question may be a little strange, but how can I receive radio waves from a country like North Korea (when I live in Poland)? I am interested in this topic, but I don't have that much knowledge. ...

This question is about digital voice modes that are used with AM / SSB / FM radios. Dstar , FreeDV , etc. assumptions: pulse width modulation amplifiers can take a digital signal as input. a software ...

I want to be able to get in touch with hams in my area when we are not both on air at the same time, but are close enough to each other for VHF communication. I want to be able to use my radio to call ...

I am having trouble understanding the 1:4 Guanella current balun here. So at DC, or low frequencies, I think the current path would be a short to ground. At higher frequencies, I am getting confused ...

I'm new to RF engineering and I want to ask how to draw magnetic and electric wall in HFSS software? I know magnetic Wall means open circuit in circuit model and electric wall means short circuit, but ...

I'm building a kit for the LNR precision mountaintopper 3 band qrp radio. I'm having problems wiring a panel mounted volume knob and speaker to hear the cw output. I'm new to home brew electronics ...

I purchased a cell phone booster for the cottage that came with an external yagi. Since its important to get the antenna as far away as possible from the indoor omni, the yagi has about 25 meters of ...

Yes, I know, this could very well be a controversial topic, so feel free to close this off if you feel it's not a good fit for this site. That said, I'm posting it here because hams (and as a ...

I'm trying to download the images in the PICT section of "----AMERICA-LINK" over my local repeater. Voice and messages work just fine, but it's not working with PICT. Steps to reproduce ...

There has been a long discussion of one question here. Phil, W8II and I agreed that it's better to post a separate question. There are several sources (some editions of "The ARRL Handbook", &...

I am newly licensed (Technician) and bought a UV-5RA as a cheap way to check out what's going on in my area and see if I'm finding it interesting enough to get a better UHF/VHF HT. The other day I was ...

I'm currently reading "Reflections: Transmission Lines and Antennas" by M. Walter Maxwell, W2DU. This book explains well why the energy is not lost because of high SWR during transmitting, ...

I was wondering whether quick testing of various commercial ISM band transmitters for operation can be accomplished with some sort of off the shelf universal receiver which only turns on a led upon ...

KK4UOT... I'm moving from Nashville, to Barcelona area Spain. My current license is for a technician, which I know is not enough to obtain an EU transmit operators, but I am curious, if I upgrade my ...

Splat seems like it's a great tool for modelling what RF coverage I should have. It can create a nice circle around me, after I download topology data from USGS, namely SRTM-1. But when the coverage ...

I recently moved to another house. My setup's current coax is 50ft/RG8x/PL259 (bought in 2018), but it is not enough for connecting my antenna to where I want to place the radio. I believe that 50ft ...

I've seen a reference to the callsign A7RW. I can't find it in the FCC database or by searching the ARRL. Is it a legitimate US callsign?

I am trying to download my Baofeng UV-5R into CHIRP for the first time and it is asking what port to pull information from. How can I find what to input here since it isn't automatically updating/ ...

I know Morse code is sometimes used by people with limited use of their hands to interact with their computer. One way is by using a straw connected to a pressure sensor, a so-called sip-n-puff or SNP....

I am new to this, having just set up my station. I have "very bad" QRN on 40m: S9. Here is the setup: High density suburb with flats and houses Yaesu FT450D with fan dipole at 6m-9m above ...

This may be slightly off topic (maybe there's a Legal Stack Exchange :-D), but how is it that codecs like Yaesu's C4FM are allowed to be proprietary while still being used on Amateur bands? At the ...

My Kenwood TH-D74 and ICom 7300 both have the ability to output IF instead AF. Is this IQ signal at 12ksps, meaning 12kHz of bandwidth, or something else? What are some projects that can be done with ...

I would like to know why are side lobes formed along with main beam in an antenna. I asked one of my colleague and he explained me that its due to radiation of frequencies near to the required center ...

Aloha! I have two HYS TC-YG05 Yagi antennas that were gifted to me and I would like to stack them side by side ( Collinear), in the vertical orientation for some local weather balloon telemetry data ...

Ferrite cores ain't cheap when you start talking about the 3 inch ID ones. I can see em for like 40 and 50 bucks.... I don't see why I can't just ground a slinky or something.

I've mostly been using a discone in the attic so far, but now I want to get proper antennas up for 2m/70cm and gmrs. I'll probably get common commercial vertical antennas. I'm not sure how much I ...

A PIN diode varies its capacitance based on a DC bias, and a Varicap exhibits this effect even more clearly. What limits the use of "solid state variable capacitors" like these for ...

I installed a Yaesu System 600with a MFJ Versatuner 2 on my 31ft sailboat and Idont know what type of cable should I use between the MFJ and the long wire antenna I have on my back Stay. Any ...

Need help in setting up the Kenwood TH-D72A for ECHOLINK. Cannot find if I need to connect to computer or some node through a local repeater.