All Questions

Filter by
Sorted by
Tagged with
0
votes
0answers
7 views

UK Intermediate training a not qualified newbie

I'm 99.9% certain that this will be OK, but independent verification would be reassuring. I am an "Intermediate" licence holder in the UK. This means that I am authorised to design and build my own ...
0
votes
1answer
20 views

Calculating receive wattage given transmit power, antennae dBi and path loss

I would like to understand how to calculate receive wattage given the following (excluding feeder loss and SWR): Transmit 50 dBm (100W) => 24 dBi directional antenna => 30 dB path loss => 24 dBi ...
0
votes
0answers
6 views

How do I alter the low power setting on a QYT KT-8900

There is no difference between the High and Low power settings. Both being around 25 watts. Is there an internal adjustment or do I have to re-program the radio?
0
votes
0answers
25 views

Is there a freely accessible repeater database?

The well-known repeater listings/apps don't provide a database that you can download and use freely for any use in building your own app. Is there a such a freely accessible repeater listing database ...
0
votes
3answers
114 views

Why EME with 100W and a single Yagi-Uda antenna is possible?

Recently I've been reading about EME and there was one thing that surprised me. Many sources claim that EME has path loss for 2m band about 252 dB. In the same time they claim (one, two): Recent ...
-3
votes
1answer
92 views

At what watt level is it safe to use metal strips for modulated signals?

In my working design, I have a transceiver TX on low power; Then boost it in a preamp phase in the back. The way I'm sending the signals (RX and TX) through the radio is by a network of 1/8 to 1/4 ...
3
votes
0answers
22 views

Where to find HF channel models or statistics?

When designing a waveform for packet radio usage, it'd be helpful to know a few things, mainly distribution of coherency bandwidths distribution of coherency times Whilst such statistics are ...
0
votes
0answers
21 views

How to send DMR SMS using MMDVM modem or hackrf?

I have a baofeng DMR radio with SMS feature, and since there is not much DMR radio owners in my area I want to do something myself. The easiest thing I can do I thought is to send myself some SMS as ...
0
votes
2answers
62 views

Yaesu FT-817 Won't transmit on 160m to 6m

I'm having the following problem with my FT-817: 1) Receives fine on all bands 2) Transmits fine on 2m and 70cm 3) Doesn't transmit at all on 160m through to 6m 4) Keying the MIC on 160m to 6m, ...
5
votes
2answers
61 views

How to properly measure sensitivity of the receiver?

I have Kenwood TH-D72 2m/70cm HT. According to the manufacturer the sensitivity is "Less than 0.18 uV". I would like to check this, since the radio is not new and I'm not it's first owner. To do this ...
0
votes
0answers
10 views

Did I enter my digital ID in Hytera PD785G?

Some time ago, I set up my Hytera PD785G. Unfortunately, I can't remember whether I have only requested my digital ID (I can look it up on ham-digital.org) or whether I have also entered it into the ...
1
vote
2answers
43 views

How to use FE-5650A rubidium frequency standard?

I bought a FE-5650A rubidium standard reference from eBay in the hope I can readily use it: https://www.ebay.com/itm/142361240786 Unfortunately this is far from "reasily useable". First and ...
-1
votes
2answers
55 views

What is an optimal amplifier arrangement with ham radios?

As I am settling on a design for a radio I need to figure out one thing: Should I modulate on low power and boost it up with a post amp, or should I go on full power right out of the gate?
0
votes
3answers
56 views

How safe is 100 watts on 2-40 meters?

So I have the misfortune of being an apartment dweller. I know that 50 watts is pretty safe as it is what first responders use on 2 meters. Am I really going to have to run around with an analyzer ...
0
votes
0answers
46 views

Small size vertical 10 m antenna with high gain

I need a directional antenna for 10 m that is less than half the size of a yagi or quad with more than about 7 dBi of gain, does anyone know if such a thing exists ?
2
votes
4answers
46 views

2.45GHz: constructing a horn of *thin* steel, what are good ways to join the edges (at least one joint along corner?)

TL/DR: How does someone make a good horn antenna system without using expensively made parts? Welding thin steel for this is not something even pro welders can do (it's a specialty app.) What are DIY ...
3
votes
5answers
131 views

Malicious interference to repeater

Our local repeater is severely sabotaged by unknown parties. For example, broadcast radio transmissions are repeated. Other times someone will send a transmission, when a qso is in progress. Local ...
2
votes
0answers
31 views

Wide band TX capable band-pass filter for VHF and Airband

I want to share the same antenna for VHF (TX/RX 144-148 MHz) and for Airband RX-only (116-136 MHz). I live on a very congested area where filter is a must, so I'm looking for the best solution for my ...
2
votes
2answers
42 views

Amateur Radio License classes in Central Iowa

I'm looking for an amateur radio license class in central Iowa, near Des Moines. I've been unable to locate anything through web searches.
0
votes
1answer
96 views

Why does the 60 meter band have special operating characteristics?

Why does this band have special operating characteristics and what do they mean.
0
votes
1answer
36 views

What are the most common EMI blockers for household computer cords, monitors, etc.?

Ferrite beaded cords, and especially double-sided ferrite beaded cords, seem especially uncommon. Are there other, perhaps more effective ways, which I should be minimizing the EMI of my overcrowded ...
0
votes
1answer
36 views

What are the practical differences between the different voice modes (and why aren't there any SSB Handheld Transceivers (HT's))?

It's my understanding that FM is used for UHF, VHF, and SSB is generally reserved for other bands. From my understanding, FM better audio quality when reception is good SSB: more efficient (can ...
-3
votes
4answers
92 views

Transmitting as SW AM station, not ham [closed]

What if I wanted to run a radio broadcast station on a commercial SW band? Say, I am on a boat in international waters. Or say I am in a free country. I monitor the frequency for months and I check ...
1
vote
1answer
57 views

Lowest cost portable HF radio with at least 100 W output?

My use case is intercontinental HF radio, and I am frequently traveling. Lugging a big rig is inconvenient and expensive ones get you into customs trouble all the time. So, I'm looking for a low cost ...
1
vote
0answers
40 views

HF propagation prediction using machine learning

Anyone out there know of or developed s/w to predict HF conditions using ML?
2
votes
0answers
68 views

Which digital modes are formally specified sufficiently to be implemented?

Which currently popular digital/SDR modes do not require a pre-compiled library or pre-written source code? (e.g. has actually been used for QSOs as implemented from specification or sufficiently ...
2
votes
0answers
33 views

Clocking A and N in a Dual-modulus PLL Prescaler

In an effort to "up my game" attempting to build a VFO for my DIY transceiver, I've been looking at PLL theory and circuits. Many of my research references are quite old and I understand that many of ...
0
votes
4answers
95 views

How do I get a ham radio license in my country?

What is the best way to get an amateur radio license in different countries? This question is a community wiki, which means that it's sort of a placeholder, an index of answers. More info Answers are ...
5
votes
2answers
317 views

CW: when I supposed to send “E E”?

I'm new to CW and one thing I couldn't figure out is when I supposed to send "E E". Let's say I'm calling CQ and somebody answers me. The QSO is almost over. Should it be ended like this: ...
0
votes
0answers
12 views

What configuration of a BJT IF amp can I use for a superhet receiver?

I am making a superhet SSB CW receiver with a crystal filter on the input after the mixer. Do I have to use IF transformers as the coupling method? Or can I use capacitor coupling with resistors as ...
3
votes
2answers
40 views

What VHF & UHF frequencies are important during an emergency?

If something bad goes down (state-wide or nationwide), what frequencies should I be tuning into? I did see this answer, but I have a BaoFeng UV-82HP which cannot do HF at all, so what are my options? ...
1
vote
2answers
76 views

Will my neighbor's amateur RF antennas effect my own utilities?

I am buying a house in the UK and the property next door has two poles for antennas. The next door lady seems to be very nice person and said her husband is an RF engineer and he used these on ...
2
votes
3answers
150 views

What Frequencies Are Open To People Without A License?

I am in rural Alaska and I am very far from anywhere that gives Ham Exams. I got a Ham Radio and I want to operate it and talk to people. However, I read that frequencies are not allowed to be ...
6
votes
1answer
71 views

Calculating the signal-to-noise ratio for CW (Morse Code) signals?

How is the signal-to-noise ratio for received CW and QRSS CW (and/or other ultra narrow-band DSP digital modes) typically computed? e.g. What noise bandwidth should be used to measure the spectrum ...
3
votes
1answer
48 views

How can i adjust the IF strip in a single conversion SSB receiver which has a product detector?

I have an analog 27 MHz transceiver which i am planning to convert to 10 m. The radio is an AM / SSB unit with a single conversion superhet receiver with an IF of 7.8 MHz using a crystal filter. This ...
2
votes
0answers
43 views

Icom 7300 low frequency broad-spectrum noise

What's causing these horizontal bands of noise? It's the middle of the day here in a low density city neighborhood. They were not present about 20 minutes ago; now they are even stronger and filling ...
2
votes
0answers
76 views

Unknown kit from DK0TV

When my father - who became a ham years after I did - passed away, I found an unstarted project (board + components), which I only re-discovered again years later. The board is marked DK0TV-001, and ...
7
votes
1answer
71 views

What exactly was a decremeter and how did they work?

In A Century of WWV, I found this mention of an unusual sounding instrument that may have once been commonplace: Calibration work was mainly focused on decremeters, instruments designed for ...
0
votes
1answer
43 views

Both OOK and FSK used in the same transmission

My gas burning heating unit takes its temperature readings from a 433 MHz thermostat, which is emitting precisely the same data packets in a packet train at some ~100 ms interval like this: 2 x OOK ...
3
votes
2answers
127 views

If I cancel my amateur license, will my address be removed from the FCC database?

When my university encouraged me to apply for an amateur radio license, they never mentioned the fact that my address would be listed on the public FCC database, for anyone who Googles my name to ...
0
votes
2answers
53 views

measures for quantifying non-linearity of a HF linear power amplifier

I am DIYing a class-AB HF Linear Power amplifier. How to quantify the non-linearity of this amplifier. What are the common measures of non-linearity as applicable to RF power amplifiers? How to ...
1
vote
3answers
100 views

can I still hear a frequency if I can only tune in 5 kHz off?

I'm trying to listen in to the telemetry frequency for Wallops Island which is 411.325 MHz. When I punch this into my radio (Baofeng UV-5R), the closest I can get is 411.320 MHz. Will I still be ...
2
votes
1answer
47 views

Is there a way to get FreeDV output level to follow the input audio amplitude?

I'm using a commonly available imbedded firmware implementation of FreeDV with an SSB HF transceiver. It seems that FreeDV encodes the input audio signal in both the frequency and time domains, ...
3
votes
1answer
60 views

What is unique about a Low Noise Amplifier (LNA)?

What is so special about a low noise amplifier? If I were to design an amplifier, I would always design an amplifier with low noise anyway. Why is it emphasised as being “Low Noise”? What are the ...
0
votes
2answers
49 views

What kind of filter should be used at the output of HF linear amplifier?

I am looking for a output filter to use with a HF linear amplifier called miniPA70 which is available through several online auction sites. The circuit is available here : http://iu3idf.blogspot.com/...
3
votes
1answer
91 views

What is “up” and “down”, and is it consistent with “top band”?

If I understand things right if you go "down" to "lower bands" you eventually get to "top band", which is 160 meter band. Since this doesn't make any sense to me, is there something I'm missing? You ...
0
votes
2answers
51 views

Can a carrier operated relay be used for T/R switching in a HF linear amplifier?

I am building the T/R switching circuit for an HF linear amplifier covering 80m band to 20m band. The current circuit takes a potential-free contact from the exciter and use this contact to turn on/...
4
votes
1answer
115 views

Last Morse call for Thomas?

What does this mean: CQ de KYHP QTC? K My father-in-law was a radio operator in the merchant marines during WWII — this was his last writing.
1
vote
1answer
90 views

Ham radio listener is split up on old hardware

I'm trying to get a ham radio listener working with RTLSDR on an old Pentium 4. Unfortunately it is playing for a few seconds, then not playing for a split second, very split up. Is there a way I can ...
2
votes
1answer
55 views

QSSTV on Linux Mint

Linux Mint MATE 64 (system is up to date) I installed qsstv first it runs normally but no CAT .. then I installed hamlib and put in the same string for the USB Device like in FlDigi which runs now ...

15 30 50 per page