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9 votes
Accepted

Are QRP transceivers only meant for CW communication?

QRP only means low power, often 1W or less. While you could technically have a 1W SSB transceiver and call it QRP, the practical range of such a radio would be limited. It is much easier to hear a ...
Phil Frost - W8II's user avatar
8 votes

Is a 5 watt UHF/VHF handheld considered QRP?

My understanding of "QRP" is simply the use of as little power as possible to make contacts over interesting distances. There isn't a specific power level that equates to "QRP" - it is more a function ...
Synchros's user avatar
  • 101
8 votes

Is a 5 watt UHF/VHF handheld considered QRP?

My personal opinion is that QRP means using significantly less power than is customary for a given mode of operation. In that sense, a 5W HT would not be QRP because pretty much everybody else with an ...
mrog's user avatar
  • 1,023
7 votes
Accepted

Using crocodile clips to make modular QRP antennas? Are there downsides?

If you look up "link dipole" or "linked dipole" you will find several designs that do just that. It works well for QRP or even for 100W. The ones I've seen have used several ...
hobbs - KC2G's user avatar
  • 12.4k
7 votes

New operator struggling to make a contact

The fact that you have made FT8 contacts means that everything is "working". You don't say where you are but say that you can hear signals all over Europe, so I am going to assume that you ...
Scott Earle's user avatar
  • 4,599
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
Accepted

How does this Pixie circuit produce a beat frequency?

Q1 forms a Colpitts crystal oscillator. It uses the reverse biased D2 as a varicap (variable capacitor) to pull the crystal frequency by 700 to 800 Hz, This frequency beats with the received frequency ...
Glenn W9IQ's user avatar
  • 18.6k
6 votes

Practical limits to maintaining coherence in an HF channel

Doppler spreading is the change in received frequency from a distance transmitter due to the rise and fall of the ionosphere along the signal path. When the effective height of the ionosphere rises, ...
pidloop's user avatar
  • 111
6 votes
Accepted

Really a Class C design?

So, my question is: Is Q2 operating in Class A or Class C? This is an OOK transmitter (on-off keying) where both oscillator and final amplifier are keyed. Keying only the final amplifier (with ...
glen_geek's user avatar
  • 941
5 votes
Accepted

Output impedance of TAPR QRPi?

The output impedance isn't especially important: in fact I believe it uses a nonlinear amplifier so the concept doesn't really apply. What does matter is the intended load impedance, which for any ...
Phil Frost - W8II's user avatar
5 votes

What is the minimum equipment necessary to get on the air with FT8?

Without getting into specific product recommendations, I believe the simplest way is as follows: Obtain a license. An amateur license is required for using amateur bands. I am not aware of any non-...
Chris K8NVH's user avatar
  • 1,042
5 votes

Are QRP transceivers only meant for CW communication?

A QRP transceiver is just a transceiver that operates on low power (usually less than 5 watts). If you look at the international Q Code, you will see that QRP simply means 'low power', and QRO means '...
Scott Earle's user avatar
  • 4,599
5 votes
Accepted

Will using a loaded coil antennas have detrimental effects on QRP operations?

Generally, making an antenna shorter makes it less efficient. This means some fraction of your transmitter's power is used to make the antenna and/or surrounding soil warmer instead of radiating where ...
Phil Frost - W8II's user avatar
5 votes

New operator struggling to make a contact

I think Scott's answer is great, and as much improvement as you can make to your antenna efficiency will be to your advantage. Based on the details you provided it's clear you have a good handle on ...
natevw - AF7TB's user avatar
4 votes

Are QRP transceivers only meant for CW communication?

CW is preferred over SSB for low power (QRP) operation because CW delivers better signal-to-noise ratio (S/N or SNR) than SSB. Because a CW signal occupies about an order of magnitude less bandwidth ...
Brian K1LI's user avatar
  • 7,858
4 votes

Does 3 W vs 5 W TX power make a huge difference in QRP CW operation?

It makes a difference of: $$ 10 \times \log_{10}\left(3 \over 5\right) = 2.2 \:\mathrm{dB} $$ How big is 2.2 dB? See How big is a decibel? It's also relevant to note: if the 12V battery is lead acid, ...
Phil Frost - W8II's user avatar
4 votes
Accepted

no contacts with Rockmite

I see what your problem is. That's a 1.4 meter long, based-loaded, telescoping, end-fed vertical antenna. It has significant losses on 40 meters. Furthermore, all end-fed antennas require a good RF ...
Mike Waters's user avatar
  • 7,986
4 votes

Is a 5 watt UHF/VHF handheld considered QRP?

Although it's highly opinionated, it may be defined as operating at 5% or less than standard 'barefoot' operating power on your band, by convention. So, for most HF, 100W is the standard power, 5W is ...
pappad's user avatar
  • 71
4 votes
Accepted

Is there anything special about 4.9152 MHz intermediate frequency?

There are not so many frequencies you can find quartzes for in large quantities and cheap and with specific parameters. If you have a lot of a value that comes in handy when you want to build a ladder ...
ha3flt's user avatar
  • 111
3 votes

Practical limits to maintaining coherence in an HF channel

If a transmitter is moving toward or away from you, the received frequency will get shifted up or down, depending on direction and rate of movement. Even if the transmitter and receiver are not ...
hotpaw2's user avatar
  • 13.4k
3 votes
Accepted

Is it possible to transmit telemetry data (GPS) via QRP?

When you ask if a QRP transmitter could be used to solve your problem, I presume that you mean a low-powered transmitter on HF, meaning roughly 3 – 30 MHz. That would solve the problem of ...
rclocher3's user avatar
  • 9,242
3 votes
Accepted

How do homebuilders find an audience to distribute kits to?

As the saying goes, if you build a better mousetrap, then the world will beat a path to your door; but in the modern era, you do need to get the word out first somehow. A website with complete ...
rclocher3's user avatar
  • 9,242
3 votes
Accepted

Does 3 W vs 5 W TX power make a huge difference in QRP CW operation?

If you haven't done much QRP operating, QRP is a funny thing. Sometimes propagation is great, and you wonder why anyone would bother with 100 W or more. I'll never forget my first DX QSO, from ...
rclocher3's user avatar
  • 9,242
3 votes

Can I power a QRP station with an USB powerbank?

I haven't experimented myself, but the USB-to-12VDC adapters surely use a boost converter, and those make RF noise. I have no idea what frequencies they make noise on (tens or hundreds of kilohertz?),...
rclocher3's user avatar
  • 9,242
3 votes
Accepted

QRP operation SOTA, what coax cable feed-line for HF?

Plenty of SOTA activators use RG-174. Being on top of a mountain more than compensates for losses in transmit power. Being in a low RF noise location more than compensates for any receive losses. One ...
Walter Underwood K6WRU's user avatar
2 votes

Tune a very short 3-5m random wire for 40m (around 7.030 MHz) for listening or occasional QRP CW sending

Clandestine can be very effective. A thin wire hanging out of your window is hard to see, especially if you only have it outside while operating. Commercially built tuners aren't expensive either. ...
Duston's user avatar
  • 939
2 votes

Are QRP transceivers only meant for CW communication?

There's at least one video on YouTube concerning a Pixie (normally a 40m QRP CW-only transceiver, with rather questionable control of harmonics) converted to use the output audio amplifier IC as a ...
Zeiss Ikon's user avatar
  • 4,097
2 votes

How do homebuilders find an audience to distribute kits to?

It happens slowly and organically. Yes, most of these folks have probably mentioned on bulletin boards, forums, or mailing lists that they have a new project they're working on. They aren't running ...
Harry Sanborn's user avatar
2 votes

Is it possible to transmit telemetry data (GPS) via QRP?

If you are just transmitting GPS coordinates and at a slow rate and need a bandwidth of about 50kbps or less then have a look at LoRa technology. It is low power, low data rate and spread spectrum but ...
AndyW's user avatar
  • 173
2 votes

Is a 5 watt UHF/VHF handheld considered QRP?

If you read contest rules, the QRP section is for those using 5W or less (sometimes 10W or less) no matter what type of transmitter you use. So you can enter the FM QRP section of a VHF or UHF contest ...
mljm's user avatar
  • 21

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