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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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 ...
1 vote
1 answer
69 views

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 ...
3 votes
1 answer
41 views

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 ...
1 vote
1 answer
43 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 ...
1 vote
1 answer
78 views

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. ...
5 votes
1 answer
61 views

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....
1 vote
1 answer
143 views

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 ...
3 votes
1 answer
150 views

RF fading channel model?

What statistical or other descriptions exist regarding modeling of an HF-band RF fading channel? This is allow making (as in code my own software) lots of simulated test input signals for an SDR ...
0 votes
1 answer
363 views

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 ...
3 votes
2 answers
118 views

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 ...
1 vote
2 answers
126 views

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 ...
1 vote
0 answers
117 views

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 ...
4 votes
2 answers
178 views

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 ...
2 votes
1 answer
132 views

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 "...
3 votes
3 answers
241 views

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 ...
6 votes
1 answer
902 views

What are these continuous sine wave tones I keep hearing?

I'm messing around on WebSDR and by just scanning through I sometimes come across these continuous tones in USB. One in particular was 28.800 MHz USB. I've picked them up on nearly every WebSDR unit ...
5 votes
6 answers
5k views

EFHW works only on one band - what am I missing?

I tried to build a multiband EFHW antenna as described in articles by PA3HHO, PD7MMA, G0KYA and many others. I decided to start with a short 40/20/(15?)/10 meters version without any loading coils. ...
6 votes
1 answer
120 views

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 ...
0 votes
0 answers
35 views

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 ...
5 votes
4 answers
2k views

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 ...
3 votes
1 answer
86 views

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? ...
11 votes
3 answers
2k views

What is the origin, history behind "Ben's Best Bent Wire"?

Bens Best Bent Wire My uncle, who was a Merchant Marine in WWII used to tell me this. He was a ham, and said it would develop my fist musically. I was a small child at the time, and through his ...
1 vote
2 answers
199 views

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?
4 votes
2 answers
104 views

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 ...
6 votes
2 answers
89 views

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 ...
1 vote
1 answer
302 views

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 ...
3 votes
2 answers
322 views

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:...
1 vote
3 answers
148 views

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 ...
4 votes
7 answers
1k views

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 ...
4 votes
3 answers
228 views

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 ...
11 votes
5 answers
3k views

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 ...
2 votes
2 answers
95 views

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 ...
5 votes
2 answers
1k views

Dipole versus ungrounded end fed for HF RX

I've built a 2 meter ground plane antenna that works pretty well for RX and has a decent SWR on 2 meters with my Alinco. However, I'm experimenting with SDR quite a bit and would really like to build ...
5 votes
2 answers
339 views

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'...
2 votes
2 answers
1k views

Modelling a "fan dipole" or "fan inverted vee" using EZNEC - unexpected result

I plan to put up a "fan inverted vee" but for various reasons I will not be able to take it down, adjust wire lengths, put it up, test, etc: I will basically have to cut the wires, put it up and leave ...
1 vote
1 answer
87 views

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 ...
1 vote
1 answer
127 views

Does the price of ham equipment normally rise during winter?

Recently licensed technician here, and going straight into my general class, I'm keeping an eye on cheap (sub-$400) HF radios. I keep reading articles that suggest used radios that normally sell for ...
6 votes
3 answers
2k views

How to stop interference on shortwave radio when connecting to a computer

I have a Tecsun PL-600 and when I can receive clear signals, and they come through just fine on headphones, and through the speaker. If I'm trying to receive RTTY or fax, when I connect the radio to ...
29 votes
2 answers
83k views

Which HF bands are best during the day and which are better at night?

I am rather new to HF operation and have recently purchased my first HF rig. I have read about bands being "open" and "closed" based on various conditions including time of day. As I have been ...
6 votes
4 answers
3k views

Can an HF antenna be put inside a tree?

There are some trees around with branchy tops that seem wider than half of 10M, maybe even half of 20M, and above the nearby rooftops. Can a wire dipole or a vertical be mounted inside a tree? If so,...
4 votes
2 answers
608 views

What is the best time of day to contact Japan from the east coast?

What are the best times in early April to contact Japan on 40M and 20M from Pennsylvania?
2 votes
2 answers
102 views

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 ...
1 vote
2 answers
174 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 ...
2 votes
1 answer
199 views

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. ...
1 vote
3 answers
546 views

Long range HF polarization

Is it possible to polarize HF signal (20-30m) at long range (thousands of km)? It was commented in my over questions that polarization is not feasible at long range. However in this article is ...
2 votes
1 answer
157 views

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 ...
3 votes
1 answer
248 views

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 ...
4 votes
3 answers
700 views

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 ...
5 votes
2 answers
2k views

RF Bridge Problem - K6BEZ Antenna Analyzer

This question regards erroneous SWR measurements of K6BEZ antenna analyzer (links gone from Internet now) design from 2013 using Arduino and AD9850 DDS modules. There have been many variations of it ...
10 votes
8 answers
8k views

What is the best time of day/Band to make a contact with Hawaii from the East Coast?

I need to get Hawaii for Worked All States, and live on the East Coast (Virginia). Furthermore, I have a poor antenna, and thus only the prime times of the day seem to really be opened for me. What ...

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