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 ...
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  • 519
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-...
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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 ...
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8 votes
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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 ...
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8 votes
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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 ...
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  • 22.9k
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, ...
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  • 18.1k
8 votes
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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 ...
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7 votes

Receiving through a linear amplifier

Every linear amplifier designed to work with a transceiver has a bypass circuit which switches the antenna between the amplifier and transceiver. When transmitting, the transceiver connector is ...
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  • 136
7 votes
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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 ...
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7 votes
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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 ...
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  • 22.9k
7 votes

Can anyone identify this military radio?

One of the fine folks from MMRCG identified this as model R-1484/PRR-15
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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 ...
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  • 22.9k
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 ...
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  • 1,159
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, ...
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  • 2,715
6 votes
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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 ...
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  • 12.4k
5 votes
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Why are commercial SDRs so limited in operating frequency?

Largely it has to do with filtering and bandwidth. An ADC requires an anti-aliasing filter to remove all input frequency components that are more than half the sample rate. Otherwise, these higher ...
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5 votes

Boefeng UV-5RE scanning capability

1) listen to FM radio, while scanning 2 meters and 70cm bands at background (as in hiking)? nope (and only 1 band scanning at a time) 2) set scan hi and low limit, via keypad and/or pc software, ...
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  • 76
5 votes

Difference between Boefeng UV-5RE Plus and UV-5

See This Chart at BaofengTech.com. Really the UV-5RE is just a cosmetic variant of the UV-5R. As to your firmware version you should check out this page at Baofengtech.com. Sadly it is not very ...
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  • 1,246
5 votes

What is the minimum signal strength I need to receive?

At 8W, the power from the radio is 9.03dB. With the cable losses of the receiving station being 1.5dB (1.41W), and the antenna receiving 1.733e-8W, it appears the received signal will never make ...
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5 votes

Frequencies as 5 digits and 6 or 7 digits

It depends mainly on the culture using the frequency, the frequency value itself and how important is each part of the frequency. In the lower frequency ranges, it's not uncommon to give the ...
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  • 2,715
5 votes
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How does a transceiver work?

The article does in illustrate things rather nicely. Let's look at the receive side first: ...
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4 votes

Difference between Boefeng UV-5RE Plus and UV-5

The main differences with these units is FIRMWARE! The firmware can be checked by powering off the unit and holding the "3" key down as you power it on. This number however does not always reflect ...
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4 votes
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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 ...
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  • 18.1k
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 ...
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4 votes
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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 ...
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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 ...
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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 ...
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  • 12.4k
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) ...
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  • 311
4 votes

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

More critical than power is length. As a rule of thumb, over distances less than 1/10th the wavelength, metal strips, ordinary wire, or anything you might use to conduct electricity is probably fine. ...
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4 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 ...
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