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Questions tagged [qrp]

Low power operation, Typically 5 watts or less

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1 answer
34 views

Configuring an antenna for (short distance) ground wave propagation on 40 m?

I'd like to use 40 m for short distance (ground wave) QRP CW. My criteria for antenna selection is simple: Works short distance (ground wave) As simple as possible As small as possible Ideally, some ...
SRobertJames's user avatar
0 votes
3 answers
187 views

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

I've done outdoor activities, POTA and WWFF, with a coax RG58 feed line with PL conectors, around 3 meters (9.8 feets), for wire EFHW antennas working HF bands (40m, 20m and 10m). Now I want to do ...
Trimax's user avatar
  • 103
1 vote
0 answers
28 views

FT-818 - no xmit in CW

I have a nearly brand new FT-818. It works fine on digital modes, phone, etc. however, when I plug in a straight key, and key the unit, it never breaks squelch. I’ve checked the Breakin setting, ...
Marvin Gabriel's user avatar
1 vote
1 answer
164 views

Swapping crystal from HF to VHF in a QRP tranceiver

I am trying to build a short-range QRP weak signal VHF 2m CW transceiver. I found a small circuit that fit my needs, but it was made for use on 40m instead of my target frequency. The circuit included ...
Jayanta Pandit's user avatar
8 votes
1 answer
241 views

Is there anything special about 4.9152 MHz intermediate frequency?

I noticed that there are several QRP transceivers that use 4.9152 MHz intermediate frequency. For instance, John Dillon, WA3RNC uses it in Penntek TR-25, TR-35 and TR-45 transceivers. Also a very ...
Aleksander Alekseev - R2AUK's user avatar
1 vote
1 answer
523 views

What is a diode for in a JFET-based audio mute circuit?

I've build the following audio mute circuit: It works fine. However in many circuits I've seen people add an extra diode on the gate of Q1: For instance, see "QRP Classics" page 120 / page ...
Aleksander Alekseev - R2AUK's user avatar
1 vote
3 answers
212 views

QRP CW on HF using FT-817ND - filter/dsp recommended?

I'm just getting into amateur radio, so just starting to gather the things I want/need. I'm only really interested in CW, and almost exclusively on HF. I'm looking into a mobile/portable setup which ...
upasaka's user avatar
  • 121
8 votes
2 answers
236 views

New operator struggling to make a contact

I got licensed a couple of weeks ago and after making 4 attempts on different days, I have made no contacts on SSB, only FT8. What I have (done): Xiegu x6100; tried 5W and 10W Par EndFedz® EFT-10/20/...
Amanda Helgström's user avatar
4 votes
1 answer
245 views

Really a Class C design?

In the March 2000 QST there was an article on the Tuna Tin QRP transmitter, which I thought I might build: The text describes Q2 as a C Class amplifier, but I just can't see how that can be true. &...
Ian_B's user avatar
  • 43
2 votes
2 answers
149 views

Can I convert an inline 1:1 CMC into a balun feed for a dipole?

I built my first 1:1 CMC transformer recently using 100 ohm CAT5e pairs in parallel. I used an FT-114-43 with 9 turns on each side and squeezed it into a small box with female coax connectors. I plan ...
wbg's user avatar
  • 301
1 vote
4 answers
946 views

Can I power a QRP station with an USB powerbank?

I recently found out there are very cheap (down to under a dollar) adapters that convert the 5 Volts from a USB port to 12 Volts. Manny small QRP stations draw very little power. For instance, the ...
EdvinW's user avatar
  • 378
1 vote
2 answers
420 views

Tuning wire with SWR LED

I have a QRP rig (Mountain Topper) and a variable capacitor QRP end fed half wave antenna with an SWR LED indicator. The LED doesn't go fully out in all configurations but there is always a local ...
Bill H.'s user avatar
  • 31
1 vote
1 answer
110 views

CW speaker and volume control

I'm building a kit for the LNR precision mountaintopper 3 band qrp radio. I'm having problems wiring a panel mounted volume knob and speaker to hear the cw output. I'm new to home brew electronics ...
Skaiser's user avatar
  • 11
3 votes
1 answer
281 views

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

I'm trying to get into backpacking QRP, which has lead me to read up on various ways to construct very portable wire antennas. I would ideally like to have a single antenna for the CW parts of the 40, ...
EdvinW's user avatar
  • 378
1 vote
1 answer
185 views

do resonant antennas need to be re-tuned in the field?

i am considering a "no tune" efhw antenna: https://qrpguys.com/qrpguys-end-fed-wire-antenna i also saw one with a tuner: https://qrpguys.com/end-fed-half-wave-sota-antenna-tuner do resonant ...
SRoberts's user avatar
2 votes
1 answer
330 views

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

I was looking for a 40 m antenna for QRP CW operation at 3 W. I looked at the Wolf river coil which is a nice portable antenna. From speaking with other hams they mentioned loaded coils are poor for ...
rsn's user avatar
  • 257
2 votes
5 answers
395 views

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

I've bought the QCX+ 40 m band radio. I will be powering this off a 12 V battery. I read on the manual the RF power at 12 V is just 3 W whereas on 15 V it is 5 W. Should I buy a boost converter for ...
rsn's user avatar
  • 257
4 votes
1 answer
115 views

no contacts with Rockmite

I finished building my Rockmite ][. It's running off of 3x 18650s, or 12v. I connected it to a MFJ-1840T and held the antenna horizontally in the air (also tried vertically) with my hand. I tried ...
mh00h's user avatar
  • 143
3 votes
1 answer
127 views

Output impedance of TAPR QRPi?

I'm a newly licensed amateur and have decided to start out by trying WSPR on a Raspberry Pi equipped with TAPR's 20m QRPi. The QRPi write-ups I've read always talk about long wire antennas but I'd ...
Bezewy's user avatar
  • 153
11 votes
6 answers
400 views

Practical limits to maintaining coherence in an HF channel

Lately I've been thinking about weak signal communication on HF. Very weak, like weaker than even WSPR could achieve. It would be nice if one could simply take any existing modulation and slow it ...
Phil Frost - W8II's user avatar
2 votes
2 answers
329 views

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

I have a GPS tracking device which was designed for inventory management, currently I'm using a GSM module to transmit the telemetry data (latitude and longitude only) to the base station. The problem ...
Sumithran's user avatar
  • 583
7 votes
5 answers
1k views

Is a 5 watt UHF/VHF handheld considered QRP?

QRP doesn't have a strict definition, though 5W or less seems to be a common threshold. So would "QRP operation" usually be considered to include UHF/VHF handhelds?
Phil Frost - W8II's user avatar
6 votes
5 answers
2k views

Are QRP transceivers only meant for CW communication?

I was just thinking about making a QRP transceiver, but are they only used for CW (Morse code) communication? If it is so, can I modify a QRP for two way audio communication?
Sumithran's user avatar
  • 583
3 votes
4 answers
169 views

How do homebuilders find an audience to distribute kits to?

Many (QRP) homebuilders offer their projects as kits. A popular series nowadays is the BITX. There are often mailing lists connected to those projects; I am a member of several. I'm wondering how ...
user avatar
4 votes
2 answers
2k views

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

To the extent that FT8 is a way to bring people into the hobby or re-ignite passion among those who haven't been on the air in a while, what's the easiest way to get someone on the air with this new ...
bcattle's user avatar
  • 255
4 votes
6 answers
2k views

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

I would like to use a small trx first for listening CW on 7030 kHz and then for transmitting, locally, among friends. My conditions are "prohibitive" as for antennas: a block of flats, 4th floor in ...
Jacek Kotowski's user avatar
1 vote
2 answers
3k views

Impedance effect of using 75 ohm coax between transmitter and an EFHW antenna

I have been given several hundred feet of very high quality 75 ohm coax. I need a run of about 36' from my QRP transmitter (FT-817 with elecraft T1 tuner) to an EFHW antenna (about 75' long). Running ...
Ron's user avatar
  • 21
2 votes
1 answer
209 views

How does this Pixie circuit produce a beat frequency?

I have two Chinese Pixie kits that I've assembled. I think they are pretty interesting, from a QRP / tinkering stand-point. Looking at the schematic below, where is the beat frequency coming from? ...
Will B - AF7EC's user avatar
0 votes
1 answer
297 views

Testing my HB-1B QRP CW Transceiver on 40m

I'm a new ham and have only used 2m/70cm so far. I have recently completed a QRP CW setup: a YouKits HB-1B transceiver and a simple wire dipole. I haven't made any contacts yet, and I'm wodering if ...
KE0FFT's user avatar
  • 1
1 vote
1 answer
578 views

Which band for portable, backpacking operation

I am going to build a QRP morse code transceiver. Due to money, I am only going to build one, for one band. I plan on taking the QRP transceiver backpacking where I will wire the antenna in a tree. ...
Skyler 440's user avatar
  • 7,620