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1answer
20 views

What might a “split-ring on a printed-circuit board” antenna for 144 MHz on a downward-looking Space Shuttle window look like? How big would it be?

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 ...
4
votes
4answers
551 views

Are there any cons of running shack on battery?

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 ...
1
vote
4answers
30 views

Extra Class Requirements and Study Guides for a General Class operator

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 ...
0
votes
1answer
31 views

How a reply system works on a aircraft transponder? [closed]

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?
0
votes
1answer
14 views

How can I import stations listed by RepeaterBook as FM and other things into my HTs with CHIRP?

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 ...
2
votes
2answers
50 views

Vertical antenna with feedpoint below ground plane?

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 ...
0
votes
2answers
52 views

Antenna suggestions for SDRPlay RSP1A

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 ...
2
votes
0answers
34 views

How might various conductive mast mounting configurations affect an electrically isolated rhombic antenna?

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 ...
0
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2answers
57 views

Tuning two antennas using wire length

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 ...
3
votes
1answer
45 views

Impedance of V Antenna as Function of Angle

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 ...
3
votes
2answers
87 views

Interpreting (noise) signals from a small untuned shielded loop

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&...
2
votes
2answers
36 views

Connecting a Katsumi Elekey EK-150 to my transceiver

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 ...
3
votes
4answers
159 views

Is a resonant antenna inherently more efficient because it couples to free space more efficiently?

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, ...
1
vote
2answers
61 views

Tuning wire with SWR LED

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 ...
2
votes
2answers
56 views

Hang wire antenna on TV antenna?

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 ...
2
votes
0answers
38 views

How is this line modulation scheme called

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 ...
0
votes
0answers
10 views

Alinco GPSTEXT/LTEXT

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 ...
4
votes
3answers
109 views

When a dipole antenna is fed via coax, what powers the ground-side of the dipole?

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 ...
1
vote
3answers
92 views

Why do we need special geometry for telecommunication antennas?

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 ...
5
votes
1answer
95 views

Has an amateur radio communication ever taken a path outside the Earth-Moon system?

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 ...
0
votes
2answers
51 views

Receiving range of ham radio on SSB with a portable radio reciever

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 ...
2
votes
1answer
84 views

Receiving shortwave frequencies from different countries (e.g. North Korea)

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. ...
0
votes
2answers
67 views

human voice / music radio signal without RF moduation

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 ...
2
votes
3answers
83 views

Store and forward system like voicemail for hams

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 ...
3
votes
2answers
58 views

1:4 Guanella unun current balun

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 ...
0
votes
0answers
22 views

Magnetic and Electric Wall in HFSS

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 ...
1
vote
1answer
58 views

CW speaker and volume control

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 ...
1
vote
1answer
59 views

Replacing a N-connector with SMA, easy?

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 ...
3
votes
1answer
271 views

Boosting Mobile Phone Reception

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 ...
-1
votes
0answers
27 views

How to download pictures over WIRES-X with Yaesu FT3D

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 ...
4
votes
4answers
201 views

(When) does a transceiver re-reflect 100% of reflected power?

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", &...
7
votes
3answers
432 views

Why don't I hear the CTCSS tones when listening on the repeater input frequency?

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 ...
0
votes
3answers
85 views

What happens to the signal level if the antenna has high SWR?

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, ...
0
votes
2answers
65 views

universal 433 MHz test lamp (receiver)

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 ...
2
votes
1answer
58 views

If I upgrade my USA license before moving to Spain, will it transfer?

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 ...
1
vote
1answer
64 views

Where can I find London borough outlines for SPLAT!

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 ...
3
votes
1answer
276 views

Recomended coax for 100ft (2m/70cm)

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 ...
4
votes
1answer
110 views

Is A7RW a legal call sign?

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?
1
vote
1answer
48 views

How can I find the input port for downloading my radio information?

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/ ...
4
votes
4answers
127 views

Could keying cw with your mouth using a sip-n-puff be as efficient as doing it by hand?

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....
4
votes
5answers
174 views

QRN: How to chase down a solid S9 noise floor on 40m only

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 ...
17
votes
3answers
2k views

Why are proprietary codecs used in amateur radio?

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 ...
2
votes
3answers
495 views

What exactly is the IF output on radios?

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 ...
5
votes
2answers
81 views

what is main reason for formation of side lobes in directional antennas?

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 ...
4
votes
2answers
73 views

Stacking Two UHF Yagi Antennas

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 ...
0
votes
2answers
91 views

Can a slinky serve as a ferrite core and if so, is there a prefered configuration? [closed]

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.
1
vote
0answers
52 views

Avoiding radio damage with closely spaced VHF/UHF antennas

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 ...
9
votes
5answers
767 views

What limits a PIN diode or varicap from being used in a “Software Defined [Radio] Filter”?

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 ...
0
votes
1answer
49 views

What type of Cable Should I use between a Long Wire antenna and a Transmatch?

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 ...
3
votes
1answer
52 views

How do I set up my radio for Echolink?

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.

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