14 votes
Accepted

Why do single band 10 meter radios exist?

There are several factors that contribute to this: CB radio and 10 meters are very close to each other. CB radios operate in the range of 26.965 to 27.405 MHz; the 10 meter band occupies 28.000 to 29....
N7QB's user avatar
  • 268
13 votes

WWV, WWVH, and WWVL may be shut down. Are there any alternatives?

In No WWVB? No problem!, KB6NU points at two projects that show you how to build your own low-powered WWVB-replacement to keep your clocks in sync: μWWVB: A Tiny WWVB Station. This project uses an ...
larsks's user avatar
  • 608
13 votes

WWV, WWVH, and WWVL may be shut down. Are there any alternatives?

GPS-based frequency standards @larsks answer rightly pointed at devices that use GPS to generate the 1-second pulsing. That's the correct way to go. Curiously, these modules only address the once-...
Marcus Müller's user avatar
12 votes

World wide Radio Module

Your problem is that there's really but one globally usable unlicensed band, and that's the 2.4 GHz band. But that doesn't sound so bad. People think "high frequency = short reach", stemming from the ...
Marcus Müller's user avatar
9 votes
Accepted

Why don't monolithic HF transceiver ICs exist?

Why aren't there monolithic HF ICs. There are, in the shape of actual (broadcast) AM receiver ICs, which can most likely with minimal effort be also used to transmit. However, are there technical ...
Marcus Müller's user avatar
9 votes
Accepted

What replaces the T/R switch in modern transceiver

Receivers and transmitters are still separated today, they are just in the same box. There is still a T/R switch too, integrated in the box. In many radios, it's a relay, same as they have been for ...
Phil Frost - W8II's user avatar
9 votes

Why do single band 10 meter radios exist?

To use parts of N7QB's answer CB radio and 10 meters are very close to each other. CB radios operate in the range of 26.965 to 27.405 MHz; the 10 meter band occupies 28.000 to 29.700 MHz. Most (...
user71659's user avatar
  • 199
8 votes
Accepted

Can I use two yagi aerials back-to-back for a bi-directional system?

Two Yagi antennas on the same antenna port could work for this application. Join the feed lines from the two antennas with a power divider for proper impedance matching. Make sure that they are ...
Kevin Reid AG6YO's user avatar
  • 24.5k
8 votes

Share wide band antenna with multiple transceivers

The basic concept is to use RF bandpass filters for each frequency range. This is frequently done by hams for VHF and UHF applications. The common term for a grouping of these filters is diplexer, ...
Glenn W9IQ's user avatar
  • 18.6k
7 votes
Accepted

Share wide band antenna with multiple transceivers

A wideband antenna is not what you're looking for – you really don't care about anything between 900 and 1500 MHz, or between 1600 and 2400 MHz. Wideband antennas are inherently hard to make, and ...
Marcus Müller's user avatar
7 votes
Accepted

Where does this common spurious transmission come from? Is there a quality difference?

This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference: Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's ...
Kevin Reid AG6YO's user avatar
  • 24.5k
7 votes

Can anyone identify this military radio?

One of the fine folks from MMRCG identified this as model R-1484/PRR-15
radiorabid's user avatar
7 votes

Swapping crystal from HF to VHF in a QRP tranceiver

Too Long; Didn't Read (tl;dr) That circuit was designed for 40 m. You can't modify it just by replacing the quartz crystal to work on 2 m. What Would Need to Change? So what you've found is a circuit ...
Marcus Müller's user avatar
6 votes

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

There is no such thing as a minimum power level at which a conductor will start radiating. If it radiates at all, then the radiation will be proportional to the power applied. Therefore, the maximum ...
Kevin Reid AG6YO's user avatar
  • 24.5k
6 votes

Need batteries for backpack operation

I used LiFePO4 (read: Lithium Iron Phosphate) for my dad's FT-891. The big advantages of LiFePo4 are: Very power dense, almost as much as Li-Ion, IIRC twice as much Wh/kg than Lead-acid Extremely ...
hjf's user avatar
  • 1,199
6 votes

Why can't we use a simple wire for receiving 2.4 GHz signals?

It might be a good idea to start by trying to make a block diagram of what you have inside of each of those controllers... Namely, the drone controller is most likely some sort of a system on a chip, ...
AndrejaKo's user avatar
  • 2,873
6 votes
Accepted

Why can't we use a simple wire for receiving 2.4 GHz signals?

A wire will pick up a GHz signal, as well as a ton of other RF signals, all mixed together. Some sort of filtering is required to separate out your desired radio signals. An Arduino has none of ...
hotpaw2's user avatar
  • 13.3k
5 votes
Accepted

Powering transceiver and SWR/power meter from same supply?

This should not be a problem at all. It is commonly done this way. Hopefully the switching supply has been designed for ham radio use. If not, you may find some "birdies" on your receiver which are ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes
Accepted

How does a transceiver work?

The article does in illustrate things rather nicely. Let's look at the receive side first: ...
Marcus Müller's user avatar
5 votes

Advantages of IQ mixer versus direct sampling SDR architectures?

A direct-sampling SDR doesn't require a mixer, which can simplify the design. Also, provided the receiver has sufficient dynamic range and processing power, a direct-sampling receiver can monitor all ...
Phil Frost - W8II's user avatar
5 votes
Accepted

How can the waterfall still be displayed during transmission

I don't know what the specific devices you're referring to do, but a couple of things are all technically possible without great effort: the ADC that is used to calculate the waterfall in receive-...
Marcus Müller's user avatar
5 votes

What does ALC do on a transceiver?

ALC, in general, stands as an abbreviation for Automatic Level Control, which is a class of circuits designed to back-feed information about the output signal to an amplifier. The goal is to change ...
jstarek's user avatar
  • 222
5 votes

Why are VHF radios so much cheaper than HF ones?

I think the premise of the question is actually incorrect. The things that make a radio expensive are receive sensitivity, output power, frequency agility, and modulation/demodulation circuit ...
user10489's user avatar
  • 5,945
4 votes
Accepted

What is Digital Mode on newer HF Transceivers

I can't comment from experience on other Yaesu transceivers, but the "Digital" mode on the Yaesu FT-857/897 is basically a second SSB/CW mode. It exists in order to have a separate, configurable group ...
Kevin Reid AG6YO's user avatar
  • 24.5k
4 votes

Why do so many HF transceivers use a UHF connector?

The "UHF" connector, as stated, is a hold-over from World War II, and has become an industry standard. A lot of hams "know" how to put them on coax, and, since radio is, overall, forgiving, most don't ...
GerryC's user avatar
  • 41
4 votes

When was the first radio transceiver (transmitter/receiver) built, and by whom?

This is tough to nail down since even the term transceiver is subject to interpretation. It is also often the case that a given answer may only be applicable for a specific geography. But with those ...
Glenn W9IQ's user avatar
  • 18.6k
4 votes
Accepted

WWV, WWVH, and WWVL may be shut down. Are there any alternatives?

Don't forget about CHU (and here is the official site) which is the Canadian equivalent to WWV. It's at lower power and it's not as well-located geographically (it's located near Ottawa), but it's ...
Jim MacKenzie VE5EV's user avatar
4 votes

Can I use two yagi aerials back-to-back for a bi-directional system?

Merely trim the reflector element of one yagi to the length of the first director and it will become bi-directional enough to get the job done without the expense of another yagi and harness. Some ...
Jim Navotney's user avatar
4 votes

How should i go about building my first transceiver?

You might want to first assemble a kit, perhaps an inexpensive one for QRP (many mail-order QRP transceiver kits seem to exist for under $100 USD). This will allow you to experience component ...
hotpaw2's user avatar
  • 13.3k
4 votes

Can the external VFO input in a Heathkit SB-(100, 101, 102) be used to operate on frequencies outside the radio's normal range?

My answer It looks to me like you could probably go further outside the limits of the band you're switched to by using an external VFO with a wider tuning range than the inbuilt LMO (5.0 to 5.5 MHz) ...
PeterH's user avatar
  • 311

Only top scored, non community-wiki answers of a minimum length are eligible