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24 views

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 ...
46 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) ...
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 ...
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 ...
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 ...
103 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 ...
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 ...
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 ...
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) ...
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....
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 &...
46 views

75 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 ...
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
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 ...
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 ...
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 ...
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 ...
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? ...
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?
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 &...
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 ...
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 ...
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 ...
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-...
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 ...
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?
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 ...
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 ...
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 ...
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?
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 ...