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votes
2answers
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) ...
0
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 ...
1
vote
1answer
97 views

Obtaining input/out impedance from S-parameters for a L network

This L network intend to transform Z1 to 50ohms. The design was made using a smith chart: The s-parameters plotted (S11 red - S22 green) in the smith chart is done sweeping the frequency from 200MHz ...
0
votes
2answers
78 views

Can timing information be used to compress data for LoRa transmission?

I have a course challenge. It involves calculating an FFT of an audio signal of 2 combined frequencies (up to 20KHz) then sending it over LoRa through to a fixed receiver. There will be an interferer. ...
1
vote
1answer
91 views

Does the price of ham equipment normally rise during winter?

Recently licensed technician here, and going straight into my general class, I'm keeping an eye on cheap (sub-$400) HF radios. I keep reading articles that suggest used radios that normally sell for ...
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 ...
3
votes
3answers
2k views

It it really useful to terminate unused 75Ω outputs on a coax splitter?

When discussing improvements to my home HDTV Antenna/distribution system a colleague brought up the need to terminate all coax, even unused splitter ports. My understanding of the way terminator ...
1
vote
2answers
825 views

Can I connect a 75 ohm antenna to a 50 ohm radio?

I have been looking for an affordable yagi antenna to use with a dual band handheld radio and I came across some very inexpensive VHF/UHF (HDTV) antennas. They are all 75 ohm though. Is it ok to use a ...
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 ...
6
votes
3answers
2k views

How to stop interference on shortwave radio when connecting to a computer

I have a Tecsun PL-600 and when I can receive clear signals, and they come through just fine on headphones, and through the speaker. If I'm trying to receive RTTY or fax, when I connect the radio to ...
2
votes
0answers
292 views

Receiving and decoding RDS in GnuRadio

I'm new in radio, so I started with seemingly easy task - receive and decode RDS data. I use GnuRadio to understand the concept of working with RF signals. So according to standard RDS receiver looks ...
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 ...
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 ...
3
votes
3answers
587 views

WSPR RX dial frequency

I tried but failed to decode WSPR using Tecsun PL-600 receiver that tunes in 1KHz step. I heard tones with good SNR but cannot be decoded. So, I mis-set it somewhere. Is it correct that transmission ...
6
votes
1answer
894 views

Cell Tower distance measurement

I am developing a hobby project to detect/measure the distance between my cell phone and a cell tower (GSM tower). I am newbie. I don't even know whether this is possible or not. I have following ...
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 ...
2
votes
1answer
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 ...
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) ...
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 ...
1
vote
1answer
83 views

Power supply for shortwave portables

I have the Tecsun PL-310ET and PL-660 SW portables which are spec’d for 5V and 6V power sources respectively. Would it damage them if I tried to power them with a 9V Bioenno battery (actual steady ...
6
votes
3answers
871 views

Can an antenna be too powerful for certain receivers?

I'm brand new to shortwave radio and have been researching what kind of a receiver to get. I'll use it on the antenna I'll build (longwire, 50-100 feet) for shortwave listening; no transmitting. Right ...
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? ...
6
votes
5answers
8k views

Shortwave Antenna Listening with Portable Receiver Like TECSUN PL-660?

I have a Tecsun PL-660 (link is to the manual) has the usual AM/FM radio telescoping internal antenna, and a 1/8th-inch jack for an external shortwave antenna. There appears to be no facility for ...
3
votes
3answers
2k views

Repairing a Tecsun PL-660

Two years ago, my father and I both received a Tecsun PL-660 radio as a Christmas gift. We both have had good experiences with our radios and generally enjoyed them until they recently both stopped ...
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 ...
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....
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 ...
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 ...
4
votes
6answers
229 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 ...
4
votes
3answers
2k views

How can I decode SSTV with only macOS software?

Have you used an SSTV decoding application on an up-to-date version of macOS? Which one, and if you built from source, can you share the steps you took to do so? I do not know of a single working ...
-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 ...
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 ...
28
votes
2answers
73k views

Which HF bands are best during the day and which are better at night?

I am rather new to HF operation and have recently purchased my first HF rig. I have read about bands being "open" and "closed" based on various conditions including time of day. As I have been ...
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 ...
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 ...
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 ...
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 ...
4
votes
5answers
283 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", &...
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 ...
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 ...
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 &...
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 ...
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'...
9
votes
4answers
16k views

2m or 70cm FM mobile radio for digital mode operation

Are there any 2m and/or 440cm FM mobile radios that have audio inputs for supporting digital modes, like PSK31 or SSTV? I have a Rigblaster that I use with my HF radio so I could get a mike cable and ...
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.
20
votes
2answers
10k views

How to detect common-mode currents or “RF in the shack”?

Let's say we already know that if your antenna is not suitably constructed or connected then you can get current on the shield of your coaxial feed line which will flow through the shielding/grounding ...
1
vote
1answer
136 views

Using SW radio to detect Jupiter

I read here (in the ideas section) that an old shortwave radio can be used as a receiver for listening to Jupiter but am unsure about how to do it. MY radio has both a whip and ferrite antenna, ...

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