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4
votes
1answer
1k views

Does a larger Biquad antenna give better results?

Consider a biquad antenna used for receiving, not for sending. They are typically built with each side having a length of $\lambda / 4$. If a biquad antenna was built with a side length of $\lambda / ...
-3
votes
2answers
190 views

Visible radio wave propagation [closed]

Has anyone actually seen a visible radio wave? If so please comment. I am just wondering if it has ever been recorded before. or if its something that was left out of NEETS or is maybe top secret.
1
vote
1answer
2k views

Can the TS-570 be fully controlled over RCP-2?

A fellow amateur here in VU-land reported the display on his 570 died. Apparently the 570 has a proprietary computer interface called RCP-2 ; Are all features on the rig available on the RCP-2?
2
votes
2answers
1k views

Digital modes on Field Day

My club is considering doing digital modes next year for Field Day. There are a few issues that we are discussing, including: What modes are most commonly used? How many contacts could be made? What ...
7
votes
1answer
687 views

Doppler Shift Compensation in Inter Satellite Communication

I am currently doing a project in the area of optical inter-satellite communication (GEO-LEO). I am using a optical carrier of 281 THz, and the Doppler shift corresponding to it is ±7 GHz. I ...
6
votes
1answer
5k views

Using standard headphones with the Yaesu FT-60?

I just got a Yaesu FT-60R handheld, along with the MH-37A4B earpiece. After having it around for a couple days, I think I'd like to be able to connect standard headphones to it, so as to be able to ...
4
votes
1answer
299 views

For Linear Transponder satellites, do I transmit on USB or LSB?

I'm in charge of our Field Day satellite communication, and I'm going to try and do this via SSB on one of the SSB satellites. I know they invert the signal, but is the convention to transmit on USB ...
15
votes
2answers
22k views

How do I make a RF propagation map for a repeater?

Let's say I have a repeater. Knowing all of the information about antenna height and gain in each direction, as well as power, how can I create a map similar to this map I saw of a repeater in ...
8
votes
2answers
4k views

How does a Dual Band Handheld Antenna work?

Looking to get a (highly recommended) NAGOYA NA-771 37cm "Dual band (2M/70cm) handheld antenna" for my Baofeng UV-5R. If my math is correct - this is about a half-wavelength antenna for 70cm, but ...
1
vote
2answers
567 views

VOIP link to repeater- simplex or duplex?

I have obtained permission by the Rocky Mountain Radio League to link my AllStar linking system node to their repeater via RF or on the input frequency. Since they have such a long tail, they will ...
5
votes
1answer
634 views

How to center-feed a single wire dipole?

I have heard that it is possible to feed single wire like a dipole from the center-point without actually making two separate wires. How would I do this, what impedance would I expect to see, and ...
9
votes
2answers
219 views

Why are PL tones strange numbers?

PL tones have very specific odd numbers with a decimal place like 103.5 or 107.2 or 88.5. The only PL tone that does not have this decimal is the 100.0 hertz tone. Why don't they just use integers ...
3
votes
3answers
1k views

How do I determine which HT antenna is better based on their very similar catalogue descriptions?

I'm considering getting an after-market antenna for my new 2 m/70 cm HT and am trying to decide which of the two antennas I should get. My primary reason for considering an alternative antenna is ...
8
votes
3answers
2k views

What sort of radiation efficiency can one expect from a folded dipole?

It is pretty well established that folded dipoles have much greater acceptable-SWR bandwidth than ordinary dipoles. Radiation efficiency is simply the quotient of radiated power to the antenna ...
3
votes
1answer
1k views

recommended capacity bottom-hat clearance above metal roof

In a few days I'm expecting to mount a Cushcraft R7000 multi-band (HF) vertical antenna on top of a metal mast that will be attached to the outside wall of a large metal shed. The aim is to have the ...
9
votes
2answers
2k views

Why is the risk of damage to a transmitter due to a mismatched antenna at lower frequencies greater?

A quick follow-up to this answer ... If the impedance mismatch is large, you risk damaging your radio, particularly on the lower frequencies ... I'm sorry to be so dense, but uh why is the risk ...
2
votes
1answer
462 views

Will these wires affect antenna performance negitavely?

We moved into a new house, and I noticed these wires sticking up for some sort of tent thing for shade. •I tested the wires to the 3rd prong in the outlet, and it showed a DC dead short to ground. •...
14
votes
3answers
16k views

What's the pinout for “Kenwood” 2.5mm TRS/3.5 mm TRS connector?

I've seen many Chinese HTs (Baofeng, Puxing, Wouxun, QuanSheng etc.) using the so-called "Kenwood connector", which has a 2.5 mm TRS connector and a 3.5 mm TRS connector. It looks something like this: ...
1
vote
1answer
444 views

What is the best resonator in Yagi antennas?

As we saw many design for this Yagi feed point. Q1 . Which one would be the best resonator / driven? Gamma match, T-match, delta match, folded dipole, quad, loop? Q2. And what is the reason if ...
6
votes
2answers
277 views

Does the waveform of the VFO necessarily have to be sinusoidal?

Looking around for a VFO online, I see most kits/manufacturers make it a point to mention the waveform. Sinusoidal is a fundamental shape, whereas others (sawtooth, square) are a composite. I recall ...
6
votes
3answers
305 views

What exactly is field day, and do I need equipment?

I have been a ham not quite long enough to experience field day. I have been excited for the weekend ever since I heard about it. I looked at the ARRL site for field days in my location, and found a ...
4
votes
2answers
2k views

What radios compare favorably with the FT-817ND? [closed]

I've been asked to specify an amateur radio for a project which is very general purpose in nature, including HF, VHF, and UHF bands. Cost and user friendliness is a concern, so I wanted to avoid ...
6
votes
4answers
668 views

Weather-proofing antenna connections

Here's a problem: you buy a fancy new vertical for a fair bit of coin, but there's no coax connector on the thing. There are just screw terminals. You need to attach coax to it, but in such a way ...
3
votes
1answer
1k views

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 ...
5
votes
2answers
115 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: ...
7
votes
7answers
40k 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.
2
votes
1answer
316 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 ...
3
votes
1answer
134 views

How does inductive base loading cause low feedpoint impedance in verticals?

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 ...
3
votes
1answer
784 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?
9
votes
5answers
5k 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 ...
4
votes
1answer
932 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 ...
6
votes
2answers
302 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 ...
6
votes
2answers
503 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 ...
5
votes
3answers
323 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?...
4
votes
1answer
315 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?
10
votes
1answer
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.
7
votes
5answers
3k 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 ...
8
votes
2answers
392 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 ...
4
votes
3answers
613 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 ...
3
votes
2answers
419 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 ...
1
vote
1answer
337 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 ...
4
votes
1answer
343 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 ...
2
votes
3answers
5k 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 ...
11
votes
7answers
36k 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 ...
3
votes
2answers
418 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?
4
votes
4answers
357 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 ...
2
votes
2answers
137 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 ...
3
votes
2answers
12k 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 ...
1
vote
1answer
4k 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 ...
4
votes
2answers
858 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 ...

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