Questions tagged [hf]
The frequency range 3-30 MHz. HF radio waves often propagate by bouncing off the ionosphere, allowing communication between continents. This tag may also be used for questions about the 160 meter band (1.8 MHz), which while not HF is often referred to as such due to its similar propagation.
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Is 100m too long for hf feed wire?
I have room to erect a DX Commander, multi-band vertical, and to give it a good number of radials on a good clear site.
Problem is I would need to run about 80 - 100m of coax feed from operating ...
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What is this vertical antenna with radials pointing up
I work next to "Koninklijk Marine Kadettenkorps Afdeling Oostende" (Royal Marine Cadet Corps Ostend). They have an antenna that I've been wondering about for years now:
It is a vertical ...
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Garage Door Opener Damaged by HF RF?
Yeah, this is a crazy one.
My wife's garage door opener stopped working yesterday. I replaced the battery and it works when very close to the garage door receiver, like underneath.
Today, my son tells ...
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HF Vertical antenna with no radial and loading coil but only ATU for 80m to 10m in a boat
I am new to HF antenna designs. I want to build an antenna for my fishing boat. My question is - if I use an ATU (like the ATU-100) and a 10m aluminium pipe as an antenna and fix it with a mast, will ...
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What is the best way to ground a whip antenna in a hotel room?
We have a 102" CB whip antenna cut for 10 meters. We're staying in a hotel and trying to figure out the best way to ground this antenna. Right now we're using a pile of wires on the floor, but we'...
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What could cause an Icom IC-756 Pro II to suddenly stop transmitting?
My HF radio (Icom IC-756 Pro II) suddenly won't receive or transmit. I recorded the sound it makes when receiving and uploaded it to https://w7bkg.org/wiki/File:Radio_Issue.wav . It sounds the same on ...
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Why are VHF radios so much cheaper than HF ones?
Why do VHF-UHF radios tend to be cheaper than HF ones? There are expensive VHF radios and relatively cheap HF ones, but finding a cheap VHF radio is much easier than finding a cheap HF radio. Why? ...
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Hi SWR with End Fed HF Wire 9:1 UNUN
Good Day
I understand every antenna set up is different, so I'm looking for advice on what I could change to alter my findings.
The set up is new including the EFHFW - 20 which was bought off the ...
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6.765 - 6.795 MHz ISM band for prototype testing
Not strictly a ham radio question, but I figure this is the most knowledgable community to ask. This question pertains to Canada, specifically.
If I were wanting to build a prototype for a commercial ...
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What balance (radials or counterpoise) do I need for a vertical hamstick as a stealth antenna?
I'm just getting back into operating after a long break. I'm currently in a ground-floor apartment of an old four-plex and I'm trying to set up a stealth-like antenna for HF. I decided on the Shark ...
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How do I test if three turns are better than 4 turns?
I built a class ab amplifier kit to use with my qrp radio. 2 watts in creates 50+ out.
This was the pa 70 amplifier kit.
It is a kit with no instructions, but a whole suite of internet videos and ...
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Where can I go for ham radio reviews? [closed]
I was wondering what would be the best startup HF transceiver for the 3-30 MHz band. I have not found any which appear to match my requirements for under $200. What would some ham radio sites be with ...
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NooElec for Startup HF Communication
I am working on setting up a Ham Radio shack for long distance communication on the HF frequency. The goal is to transmit 1,200km from Alberta to Manitoba using skywave propagation. I would need to be ...
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Measuring effectiveness of vehicle bonding
Is there any objective way to measure the effectiveness of your bonding in a mobile HF setup? Or determining when you have "adequate" bonding? I have a hard time with just throwing straps on ...
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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 ...
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Centre pole construction for 20 metre half wave dipole
I am about to embark on the construction of an inverted V half wave dipole. It will possibly be multi-band but, for the moment, I want to build it for 20M. Because of the shape of my property, I would ...
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What lengths of counterpoise is suitable to support a 58 foot "random wire" antenna?
I am a technician interested in building my first antenna. I want to explore HF bands, 160m - 6m. Quick impedance calculations indicate that a 58 ft "random wire" antenna could work for this....
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End fed long wire antenna for 40 meters length
I have a hex beam antenna that gets me onto bands from 20 meters to 6 meters very well.
I wish to have an antenna that gets me onto 40 meters at night very well also.
Recently I purchased an end fed ...
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Swan 350 calibration
So my swan 350 needs to sing properly and order it for to do so the VFO needs to be calibrated. I do not have a working frequency counter.
How do I get this stuff fixed so I can get her singing right.
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Can an 80 meter band dipole work in a basement?
I don't have an HOA, but I don't: a. have the space outside for an 80 meter dipole, nor: b. does my wife want visible antennas on the outside of the house.
So I've been in the mode of finding an ...
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Need help in the fabrication of an UHF power amplifier
I recently decided to conceive a 10W class 446MHz amplifier.
I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier :
SKY65162 to amplify the signal to ...
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Can I use my CB mobile antenna with a 10 meter radio also?
I have a mobile mounted CB antenna that has an SWR of 1.5 on channel 20. Is it possible to use it with a 10 meter radio? I do not have enough room on my car for an additional antenna, so if it is ...
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Antenna options for a small urban garden
I've narrowed down my antenna options to fit a small urban garden. It's tough, space is tight and a neighbour three doors down reports everything I do to the council so I'm routinely inspected for ...
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How do I choose between T37-2 vs T37-6 for this High-Pass Filter?
My RTL-SDR V3 is being overloaded by an AM broadcast so I'd like to build a high-pass filter to block the AM broadcast band. I thought I'd start simple and try making the one shown in Fig 3 of "...
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So how do HF nets work, anyways?
I'm familiar with VHF/UHF repeater-based nets and the general concept of how nets work (net controller that you check in with, net controller says who talks, people send it back to the controller ...
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Could my HF antenna cause problems to these other antennas on the roof? [duplicate]
I am planning to purchase a property soon in an apartment block on the top floor. I am very very keen to install a HF multiband Yagi antenna on the rooftop.
I notice some small cell towers and a ...
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Do these look like amateur radio antennas?
I am planning to move into a new apartment, and of course would like to install a HF antenna there, on the roof if possible.
Today I noticed a small Yagi antenna on the roof of the building , more ...
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What steps to take to secure for G2 geomagnetic storm?
So I see NASA has issued a geomagnetic storm watch for a possible G2-level storm on the 11th. I’m at about 53 degrees north geomagnetic latitude.
Is this something I need to care about equipment-wise? ...
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What is the minimum height required for a 60 meter NVIS antenna?
Various answers include 1/8th of the wavelength all the way down to 1/10th, but would 1/15th or even 1/20th of the wavelength be sufficient for a 60 meter (5 MHz) horizontal NVIS antenna?
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Mounting a hex beam on top of a high urban building
I am moving into a new apartment in the city soon which is on the 24th and last floor of an apartment building. I will have access to the roof of the building also.
I'm still trying to understand ...
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Common-mode choke (CMC) hurting my SWR. Live with it? Drop the choke?
I have been using a Par EndFedz Mk2 Trail Friendly 40/20/10 though using the matchbox from an EndFedz EF-QUAD (with Vibroplex’s blessing) so I could transmit at more than 25W. On all three bands I ...
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Mounting a vertical antenna on a fiberglass mast
I have a multiband SE-X80 HF vertical antenna which works ok from 20 meters to 10 meters with a tuner. It is attached to the railings of my apartment balcony at the moment. This is the antenna : https:...
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HF SSB etiquette when someone is working quick but not contesting and you're not sure they got you?
When someone is working quickly -- clearly trying to work a lot of stations -- but pretty clearly isn't contesting, what's the etiquette when they 73 you and end the contact but you're not sure they ...
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What's the realistic SSB reception range for 25W on 20m and 40m?
Because of my living situation I am using a Par EndFedz Mk II Trail Friendly antenna with my IC-7300, since it can do 40m and 20m and is only 41 feet long. However, it can only handle 25W.
Now, for ...
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Why do operators mention the band when calling CQ on phone?
I'm a new-ish ham, licenced for about one year now.
Within that year I've heard a lot of CQ calls from other hams on phone (both HF and VHF), and it seems that a large portion of hams routinely ...
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Does a NVIS antenna have to be exactly below the maximum NVIS frequency to have NVIS characteristics?
For example if the maximum NVIS frequency is 5 MHz in a given region, would a NVIS antenna have to be resonant at less than 5 MHz to have NVIS propagation characteristics or can it be slightly above ...
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RF ground confusion
I'm a bit confused by RF grounding. Let's take a HF 1/4 wave vertical antenna for example.
When current flows through the centre of the coax to the antenna, my understanding is that the current then ...
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How to check second-hand ICOM IC-718?
I’m buying a used IC-718 from a local ham. I can verify its function before I decide to buy. I’ve read the manual and know the functions and capabilities.
What should I check / look for, apart from ...
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Recommendations for Antennas installation with Steep slopes
I have a property that I am trying to figure out the right antenna setup for.
Transmission Goals
North of this property is 900 miles to communicate 80M or 40M.
Also want to communicate to another ...
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Understanding low MUF in VOACAP
I've started playing with VOACAP to better plan and predict conditions on 27 MHz (CB). To my utter astonishment, VOACAP says that I won't be able to communicate on that frequency, regardless of ...
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Choosing a Relay for HF Applications
As part of my 20m transceiver build I'm looking for a relay to by-pass an RF amplifier in the front-end board. So, to be clear, that's after the 20m broad bandpass filter and before the RF mixer (it'...
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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 ...
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Hang wire antenna on TV antenna?
I have a TV antenna on the top of my house that I don't use. It is the highest point around so I would like to hang a wire antenna (for HF) on it. Is an inactive antenna going to cause any ...
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Receiving shortwave frequencies from different countries (e.g. North Korea)
This question may be a little strange, but how can I receive radio waves from a country like North Korea (when I live in Poland)? I am interested in this topic, but I don't have that much knowledge. ...
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QRN: How to chase down a solid S9 noise floor on 40m only
I am new to this, having just set up my station. I have "very bad" QRN on 40m: S9. Here is the setup:
High density suburb with flats and houses
Yaesu FT450D with fan dipole at 6m-9m above ...
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Troubleshoot ICOM IC-745 intermittently shows no power on transmit
I have an old IC-745 I bought used last year. Recently it seems to be malfunctioning intermittently. It is receiving well on all bands as far as I can tell. Sometimes when transmitting, there is no RF ...
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Is testing SWR *practically* less important for 2m/70cm than HF bands?
Totally new amateur operator and I've noticed that a lot of material e.g. Your Tube videos, blogs, forums when discussing metering VSWR mainkly seem to be talking about HF bands. I also see fewer VSWR ...
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Lowest noise MMIC for HF? (160-20M)
I recently learned that these fancy modern ultra-low noise MMIC, while having <1dB noise figure around 1Ghz could be quite bad at low frequencies due to 1/f noise.
What is lowest noise MMIC then ...
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Why is QRN so bad on the low HF and MF bands?
If one tunes an HF/MF radio at night, the lower the frequency (or the longer the wavelength) of the band, the more QRN (static and atmospheric noise) there is. 80m is noisier than 40m, and 160m is ...
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If receive performance doesn't depend on SWR, then how can I tune my manual HF antenna tuner by band noise?
The popular question "What is the relationship between SWR and receive performance?" asks if a receiver with a well-matched antenna (low SWR) beats a receiver with a poorly-matched antenna, ...
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