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How does adjusting the sleeve on antenna traps tune an antenna?

Take for example, the Hustler 4BTV. It has traps formed by an inductor, covered by a sleeve that's connected at the lower end, and the upper end is covered by a non-conductive cap: The tuning ...
114 views

LOS One-way radio system, 4km with at least 1000bytes/s

In order to track skydivers/BASE-jumpers with flysight I am looking for a one-way radio system to transmit the location data. System needs the following specifications: ...
33k views

End-fed wire antenna lengths

I want to use an end-fed wire antenna, but what would be the best length of wire for the 20m and 40m bands? Is there a way to work this out? This is assuming a tuner will be used.
312 views

What is this matching technique called?

I've had this suggested to match 50 ohm coax to a lower feedpoint impedance, like a vertical, especially mobile shortened verticals. What's it called? simulate this circuit – Schematic created ...
130 views

As an extreme example, take mobile HF antennas. These can have very low feedpoint impedances, maybe as low as $6\Omega$. The ideal impedance of a quarter/wave vertical is $36\Omega$, but electrically ...
734 views

Closest antenna to an isotropic? [closed]

What is the closest antenna ever made to an isotropic antenna? That is, has the same gain in every direction in free space?
4k views

Is it illegal to key up and not identify?

So, I key up on a repeater to see if it works, or to see what cool courtesy tone they are using. I don't do anything else. Is it illegal or bad ham radio etiquette to just key up for a second, key ...
896 views

Bicycle mobile antenna

I have mounted mobile verticals (mag mounts) on my bicycle, but I have learnt that a bike does not have a good RF ground because there is nothing close to a plane. Without wasting too much more ...
290 views

What rig or rigs are onboard the ISS?

This article mentions the Ham Shack aboard the ISS. From the picture it looks like a small very light rig like a Yaesu FT-817. What radio(s) do the astronauts use when they talk to Hams and School-age ...
446 views

How to increase antenna aperture?

I know that in the short wavelength region, where parabolic antennas are used, the aperture can be increased simply by making the dish larger, as is the case with the radio telescopes. But how to do ...
319 views

Energy vs power in transmitters

Higher frequencies have a higher energy, simply stated by Planck's constant. When I am transmitting 100 watts on 500 kHz, and transmitting 100 watts on 5 GHz, is there an energy difference in the wave?...
305 views

2 m meteor scatter FM voice freq?

What frequency should I use to try and make meteor scatter contacts on 2m FM tonight, with a nice meteor storm coming?
1k views

Fastest Speed allowed for CW FM repeater ID in USA

What is the fastest legal WPM I can use for my repeater's Morse code identification? I am in the USA.
2k views

Using Earth as an RF ground

I have built a simple ground plane antenna for 70cm with a connector, 4 radials, and one vertical element. The RF ground is connected to the radials, and the RF is connected to the vertical. It got ...
355 views

Why is an RF ground not as critical as the other, and can they be used backwards?

I will give the magmount antenna as an example: The vertical element to the antenna is very critical, cut to a certain wavelength, often added with some loading coils, or a little spiral to make ...
527 views

Consistency of Morse Code/CW sending speed

How important is it to maintain a consistent Morse Code WPM keying speed when transmitting CW? I occasionally hear operators slow way down when sending RST and location info, and then later ...
411 views

Is it possible to radio between America and India?

My friend and I want to see if we can Ham radio between San Jose, CA and Bangalore, India. We're beginners and are going to be using handheld radios. Are there any networks of repeaters, that could ...
326 views

How do you operate an “up 3” split dx station with a Kenwood TS570 or similar HF radio?

My Kenwood has "split" and "rit/xit". Is the "split" mode suitable for operating a split for a DX pileup situation, where a station is listening "3 up"? I'm confused about which of the larger or ...
332 views

How to choose a coaxial cable

How do you know which coaxial cable to choose for your application? For instance; I require a cable that has a 50ohm impedance, an operating frequency of 2.4GHz, length of 100mm, and needs to be ...
4k views

Baofeng uv-82 will not transmit in channel mode?

I have 2 Boafeng UV-82 radios. I programmed the frequencies using Chirp. When I try to access the repeaters in channel mode I cannot connect. When I switch to frequency mode and turn off the duplex ...
31k views

What is a Gamma match in the context of the driven element of a Yagi antenna?

How (and why) does a Gamma match work, when used on the driven element of a Yagi antenna? As shown here: (source: http://www.iw5edi.com/ham-radio/?2-element-yagi-for-10-meters-band,49) The article ...
383 views

Can two FM radios transmit two separate PL tones at the same time, and be received by two radios with matching PL tones?

Can two FM radios transmit two separate PL tones, and be received by two radios with matching PL tones? Or will the receivers hear a mix of the two, or nothing at all?
318 views

Should the capacitance or inductance be varied to achieve resonance?

A resonant circuit is typically composed of some resistance and reactance, the latter being provided by inductors and capacitors. The resonant frequency being calculated as the inverse square of their ...
131 views

Capacitance methods (antenna extensions, whole body as antenna) for receiving better

I have seen that there are times where reception isn't very good on a radio, but as soon as the hand is approached as much as possible to the antenna (with or without direct contact to the actual ...
11k views

Spacing between elements on a Yagi antenna

Does anyone know what the spacing between elements on a beam antenna should be? I built a 146 MHz 3 element beam following instructions, and the spacing was 16" between the driven element and the ...
3k views

Remote control for Icom IC-7100

I just got my new Icom 7100, and while I'd love to operate it locally, there are just too many things near me that get interfered with from RF. As such, one solution is to remotely control it - I ...
831 views

Wouxun KG-UV6D PMR frequency “spillover”

So I recently bought a pair of Wouxun KG-UV6D. We don't have the license required to operate outside of PMR frequencies, but that's fine, as we will be using these for airsoft. The programming of 8 ...
103 views

Under what circumstance does non-toroid former lend itself to HF?

Many HF circuits posted in my copy of the ARRL manual (1972 edn - Yes, it's a vintage) appear to use a toroidal former with a coil. The same applies to HF circuits posted on the internet. From what I ...
2k views

How to combine two 50 Ω antennas such that they appear as one 50 Ω load?

I'm looking for a simple way to impedance match an array of two 50 Ω antennas so that when they are combined they appear as one 50 Ω load. Assume that both antennas are identically constructed, are ...
5k views

What is a CQ contest and what is the proper way to respond to a CQ contest call?

As I listen, I often hear stations calling "CQ contest". When I hear stations respond, they seem to do so with a specific set of information. I recognize the call sign and a signal report but there ...
2k views

How to make a loop antenna for HF?

While researching this answer, I came across information that indicates that a many good Low Frequency/ Very Low Frequency antennas are loops, with high directionality and good overall characteristics....
65k 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 ...
463 views

Can an external VFO be injected into a commercial rig?

Constraints of various kinds preclude any investment in a rig at present; so I find myself pondering the means to get back on the band piece-meal. Say I were successful in an attempt to throw ...
290 views

How to stack circular polarised antennas

I'm interested in stacking a pair of circularly polarized "crosshair" antennas. Do I construct such as both antennas are in phase with one another then match the two signals in phase via the coax line,...
2k views

What makes JT65 preferable for VHF, and JT9 for HF

Are the bands really that different in characteristics where JT65 works better for VHF, and JT9 for HF? The claim comes from the WSJT website: JT65 was designed for EME (“moonbounce”) on the VHF/...
1k views

Is there a “proper” phonetic alphabet to use with voice communications?

When I took my Technician test some 20 years or so ago, we had to memorize the phonetic alphabet, which I think is the same one used in the military. I was taught that it was international, similar to ...
184 views

What is the largest amateur satellite in orbit through 2014?

What is the largest, and what were the dimensions of the largest amateur radio designated satellite in Earth orbit as of, or up until, 2014 other than the International space station.
3k views

What does sending SK after calling CQ mean?

When I was at a local radio club today, I witnessed a bit unusual response by a station calling CQ using BPSK31, that is to say phase-shift keying, not the regular A1A telegraphy, on the 20 meter band....
510 views

How can I use the 455kHz IF signal?

As I own a PL-660, I saw a post that 455kHz IF signal can be obtained by connecting a wire to the board. I wonder, if I can tune to any signal by using this IF signal by SDR? And what are some common ...
79 views

What is the best solution to transmit data by the ionosphere over at least 7500 km? [closed]

I know that some amateur radio are using some frequencies that are reflecting on the ionosphere to transmit data over super long distances. I am wondering if it is possible, without an insane lot of ...
383 views

What are some characteristics, when sending CW, of a "bad fist"? How bad can it get, typically, and still manage to communicate the message text sent to a human operator on the receiving end? Contra-...
880 views

Spacing between words in CW using Farnsworth timing?

What is the proper way to calculate or determine the amount of time between words (the key up of the last character of one word to the key down of the first character of the next word) when using ...
7k views

Vertical Antennas: Compare Cushcraft R9, no radials to 43 foot vertical with ground radials

Small lot, must go vertical. Which antenna will preform better, with less noise, good DX. Cushcraft R9, NO ground radials. Or, 43' with ground radials.
181 views

Identifying regulations for interfering stations

I'm working on tracking down some 2m repeater interference, and I have identified that the offending signal is a spur transmission on a commercial pager service (that lands right on our repeater input ...
1k views

How do I get a coordinated frequency assigned for my repeater?

I am thinking about putting up a 70cm repeater up on my High School, where they have a very tall roof. By the time It is ready to put it up, I want to make sure a frequency is reserved for the ...
2k views

What kind of antenna has a spiral connected to a reflector like this picture?

The description on the antenna says it is used for satellite communication, but it was taken in 1984. Is this an antenna style that is still in use? What is it called? What kind of gain should be ...
3k views

Why does ice on a wire dipole affect the SWR?

We just had snow and ice overnight and my wire dipole was coated in ice. Why does the ice covering negatively affect the SWR of the antenna?
2k views

How does a “chip antenna” work?

How does a tiny surface-mount "chip antenna" for the 2.x thru 5.x GHz frequency bands work? What allows such a tiny item to radiate or receive RF with some amount of efficiency? What allows a chip ...