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votes
0answers
24 views

Isolated linearly loaded antenna?

Is there a name or common descriptive term for a linearly loaded dipole or end-fed, where a (near) parallel loading element or elements are not connected (galvanically isolated) to the fed element or ...
0
votes
2answers
50 views

Can an end-fed be fed with an Isolation transformer?

Typical half-wave end-fed antenna kits include either a 9:1 or 49:1 toroidal balun or unun, which is a transformer for impedance matching, but with one primary winding endpoint (for the coax shield) ...
2
votes
1answer
26 views

Net log and QSO submission question

New ham here. Is it common practice and acceptable to submit net logs as QSOs to QRZ, eQSL, LoTW, etc? One person told me they log other's callsigns checking in to a net they're participating in and ...
0
votes
1answer
45 views

Looking for a way to create a radio link between a pair of antique telegraph keys

I'm trying to design a way to link up two antique telegraph keys wirelessly. This is for a friend to use with his granddaughter between the house and the playhouse, so we plan to use FRS to avoid ...
0
votes
2answers
97 views

Can I communicate 40 miles away with a base setup

I’m wanting to get a ham radio license and a good base station set up in my home. The reasoning is to communicate to my family approximately 40 miles away from me in case of a emergency or SHTF ...
4
votes
1answer
104 views

Why are loopstick ferrite antennas commonly wound with Litz wire?

What is the advantage of using Litz wire to wind ferrite (loopstick) antennas? How much of an advantage in what characteristic does this type of wire provide? (over generic single strand enameled or ...
2
votes
2answers
64 views

How to compute the efficency of an omnidirectional antenna from its gain?

Some antennas have very limited specifications with no stated efficiency. For example, this antenna has the following specifications: Frequency Band 902-928 MHz VSWR <2.0:1 Impedance 50 Ω Gain ...
3
votes
1answer
43 views

How does a loopstick antenna actually receive signal?

Around 1970, I acquired a little transistor radio (powered by 4xAA cells, 6V) that had no external antenna. Inside the back panel (which opened to allow replacing the battery cells) one could see the ...
3
votes
3answers
467 views

Measurement of antenna with VNA does not match its specs

I have a NanoVNA V2 Plus (50kHz - 3GHz) and decided to test my LoRa antennas: an unknown antenna delivered with a LoRaWAN gateway (RAK831) a 868Mhz antenna from Linx Technologies (ANT-868-OC-LG-RPS) ...
1
vote
2answers
59 views

Can I wind my 9:1 unun with two wires instead of three?

All the 9:1 unun tutorials out there are using three wires to wind, but I was wondering if it is possible to wind it using two wires similar to how this 49:1 is built (https://elginradio.files....
0
votes
1answer
31 views

My Tecsun pl_660 Radio display is not working. Cannot see any thing except display light

My Tecsum PL_660 Radio display is not showing any kind of frequencies. When ever I press any button on the radio nothing shows up on the display. Kindly suggest what need to be done for the problem ...
3
votes
2answers
56 views

When is it relevant to consider a trace as a RF transmission line

I'm building a simple Greinacher based RF Power meter for the PMR band i.e 446MHz. I intend it to work as a confirmation device and not something really acurate. The circuit is quite simple: The led ...
0
votes
0answers
65 views

Legal unlicensed transmitters permitted where? [closed]

In what English-speaking countries is it specifically allowed by law or regulation to operate non-commercial unlicensed RF transmitters within certain bands at certain power levels? (such as within ...
0
votes
3answers
93 views

Is it possible to boost WIFI signal? [closed]

Whilst strictly not radio ham question, it does fall in to the RF area so hopefully this is not too far off topic... I have BT broadband account which entitles me to use BT-WIFI hotspots. The trouble ...
3
votes
2answers
73 views

How to figure out my car battery's capacity?

I was participating in an emergency radio training and I was asked how long I could operate. I'm using an old car battery, which was sometimes not capable of starting the car in winter, which is why I ...
-1
votes
4answers
119 views

What comes first, Voltage or Current?

Impedance can be defined as cause / effect or Z = E / I. This means that a difference in voltage potential causes a flow of current, the rate of current flow depending on the impedance. In a dipole ...
1
vote
0answers
36 views

For a resonant half wave dipole, is the phase of the applied RF voltage at the feedpoint in phase with the current reflected from the ends?

For a resonant half wave dipole, the voltage and current of the standing waves on the antenna are 90 degrees out of phase with each other. At resonance, is the phase of the current reflected back from ...
2
votes
1answer
83 views

Does SWR change along the length of a transmission line?

Wikipedia says "SWR is defined as the ratio of the partial standing wave's amplitude at an antinode (maximum) to the amplitude at a node (minimum) along the line". Standing wave voltage ...
0
votes
1answer
39 views

The amplifier does not work for hack rf one

Good day! I ask for help with repairing the hackrf one amplifier. Doesn't work at all. Accepts signals without amplifier, and LNA and VGA adjustment in SDR sharp works too! But when I put a tick on &...
1
vote
2answers
46 views

Is power output or something else to blame for my duplexer failing?

A Ham buddy of mine and I were trying to setup a UHF repeater in our area due to a lack of them. We had two Motorola CDMs, one a 1250 and one a 1550, and we purchased a $200 or so reject only duplexer ...
1
vote
2answers
123 views

What do radials really do for a vertical antenna?

I have read everything I can find about monopole (vertical antenna) radials, and also watched many YouTube videos that touch on the topic. I see conflicting information about what they do, where a ...
1
vote
2answers
99 views

Can a smartphone with single antenna receive signals modulated by different schemes

I am working on a system whereby a smartphone may receive signals simultaneously from different sources. As we know, the fading and pathloss will make the transmitters send their traffic with ...
4
votes
1answer
100 views

Choosing a Relay for HF Applications

As part of my 20m transceiver build I'm looking for a relay to by-pass an RF amplifier in the front-end board. So, to be clear, that's after the 20m broad bandpass filter and before the RF mixer (it'...
1
vote
3answers
151 views

Aren't all antennas technically dipoles?

Since all antennas require a ground, reference or otherwise, there are two poles for their operation. For a mag mount, the car body is the reference ground. A vertical cannot operate without a ground ...
0
votes
2answers
64 views

At near-QRP levels should I include a balun/unun in the antenna system? [duplicate]

To my comprehension a BALUN/UNUN is an RF Transformer. If this is correct and since a BALUN/UNUN is part of the antenna system ... how much power does one expect to lose there? Specifically, how much ...
1
vote
0answers
26 views

How does the inductive reversal process of the emission of EM radiation at the receiving antenna work?

The emission of EM radiation is based on an induction process in which a periodic electrical voltage creates a magnetic field that is offset by 90° in time and space, also known as the starting near ...
0
votes
0answers
29 views

I'm trying to configure HRD for IC7300 but cannot connect / detect frequency

Got the firmware updated. Got the Driver updated. Got the software updated. Went through instructions several times.
2
votes
1answer
59 views

Apparent Paradox about wave reflection in a transmission line?

The transmission line is without loss of length λ / 4, the load $Z_L$ is a short circuit and $Z_G = Z_0$. At $t = 0$, an incident wave of voltage $V_1$ and current $I_1$ such that $V_1 = Z_0 * I_1$ ...
2
votes
1answer
77 views

Yagi antenna isolation from other Yagi antennas

I have multiple Yagi antennas horizontally polarized. They are all placed in closed proximity at the same height horizontally and operating in a similar frequency. The yagis are 2.45GHz, bluetooth ...
-3
votes
1answer
91 views

How can I jam cell phone communications with gnu radio and hackrf? [closed]

I need to make this project, plase help me with some ideas
3
votes
2answers
66 views

Ground plane reflects RF or brings it to ground

I'm still confused with the purpose of a ground plane purpose in an antenna. My understanding is this. If an antenna is perfectly balanced, there will be no common-mode currents going to ground. If an ...
2
votes
2answers
99 views

How much dB gain do you need from an LNA in front of an antenna for great low-signal reception from satellites in the 2m and 70cm bands?

We are building a multi-stage LNA for a TR module we are building in the 144MHz and 440MHz range. This LNA we are considering (Qorvo QPL9547) provides about 22dB gain in the 2m and about 27dB in the ...
0
votes
1answer
59 views

What would cause 3 bursts of FM radio interference every ~3.5 seconds

I’m trying to locate the source of some interference on the FM band — it’s audible as 3 quick staccato bursts of brownish noise approximately every 3.5 seconds. It’s more pronounced at the low end of ...
4
votes
3answers
82 views

3D Printed yagi antenna

I'm trying to produce a Yagi antenna for the 2.45 GHz band using a 3D dual extruder printer. The idea is to print the antenna elements using a metal filament and encasing it all in plastic. The ...
0
votes
1answer
62 views

Where can I find a service manual for the TECSUN PL-660 to replace the failed circuit board flex cable myself?

Diagnosed three nonfunctional TECSUN PL-660 radios (one from eBay Anon-CO, and two from Amazon) where can I find a service manual to replace the failed circuit board flex cable board assembly part? ...
1
vote
0answers
31 views

Audio Interface wiring diagram of Yaesu FT-65 TNC cable

I want to imitate this cable, but I don't know-how. Yaesu FT-65 TNC cable. Is it need to series a resistor inside of those?
18
votes
5answers
8k views

FCC sends “Notice of Dismissal” with quite threatening language just for denial of a vanity callsign?

I had applied for a vanity callsign which wasn't available. That was in March. The FCC license system shows my old callsign is still in effect. Today, after a longer absence from my mail, I open a &...
3
votes
2answers
208 views

NanoVNA(v2)… what to capture for future reference when comparing past antennas?

I'm designing a HF antenna that uses a portion of a downspout (electrically isolated from the gutters above and lower portion) as a bottom-loaded shortened quarter-wave vertical. I'm about to trim the ...
3
votes
2answers
126 views

Antenna traps - problem with frequency change

I built a two-band antenna (20 and 40m) with traps. I made the traps as a parallel LC circuit on the AL7 toroidal core (3 MHz - 40 MHz), I also used a 1KV ceramic capacitor. I've tuned everything up ...
3
votes
1answer
70 views

Why is my experiment to produce 3rd order harmonics by saturating a receiver not working

I've been trying to devise an experiment to produce a third order harmonic in radio receiver that's been saturated, but I'm not seeing the expected results. My understanding of the theory is that when ...
3
votes
1answer
179 views

Globar resistor repair or alternative(s)?

I am restoring a Hallicrafters S-120 receiver and when trying to unsolder the wires, from the electrolytic capacitor, I noticed that one of the terminals of the Globar resistor (880-100 Ohm / 023-...
4
votes
2answers
192 views

What is proper procedure for asking for “distant” contacts on 2m FM on simplex?

As a new ham, just for fun, I'm planning to hike up to the local high point (which while not high in an absolute sense does have a commanding view of the surroundings) with my 5 watt FT-4XR and a slim ...
20
votes
1answer
4k views

Why do people say, “get a nickel,” on repeaters?

Sometimes, I'll hear someone say "wait a moment, I'm getting a nickel," and then drop the carrier only to resume talking. Why?
2
votes
1answer
65 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 ...
5
votes
4answers
1k 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 ...
2
votes
6answers
84 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
45 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
26 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 ...
3
votes
2answers
70 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
74 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 ...

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