Glenn W9IQ
  • Member for 4 years, 9 months
  • Last seen more than a month ago
Repeater for 1/4 square mile campus
1 votes

This question is largely a continuation of your previous question so I will only address the unique aspects here. A repeater will generally only serve one pair of frequencies so it is limited to one ...

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Repeating UHF Handheld via UHF vehicle transceiver
1 votes

First, let's start on the legal side of the equation. If you are in the US, you are required to have a license for your business radios as well as for your planned repeater. You do not get to pick the ...

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Can timing information be used to compress data for LoRa transmission?
3 votes

I think you are taking the wrong approach. Take some time to look at the overhead of a LoRa packet. It contains addressing, checksums, handshaking, etc. It is a large enough overhead that sending one ...

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Wiring questions: grounding, attic antennas, BNC connectors
5 votes

If you are in a jurisdiction that requires compliance with the US NEC (National Electric Code), you will probably find that there is no requirement for grounding the cable or having a lightning ...

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In HLDC framing/Bell202 encoding, are the flag bytes NZRI encoded?
Accepted answer
1 votes

The challenge with the HDLC/Bell 202 "standard" is that it is poorly defined and so it results in varietal implementations. One is often left to test a questionable element against a variety of ...

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Stacking DB8 "bedsprings"
2 votes

The degree of additional gain from phasing two of the arrays will largely come down to the phasing harness and the balun. Since you are focusing on a single UHF frequency, I recommend an open line ...

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Using approximate signal strength at a distance to estimate reception strength of a radio station
Accepted answer
3 votes

We have some clues from a historical perspective. In the January 1917 edition of The Radio Experimentor, author H. Winfield Secor noted that approximately 50 kW (kilo-watts) of transmitter power was ...

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Running mag loop feedline INSIDE the loop tube
1 votes

It is a tough call. Clearly the inside of the tube carries no RF current. This would suggest that routing the coax in the tube would be a safe approach. But my concern is that where the coax exits ...

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78.5MHz AM receiver self-oscillation
2 votes

When designing circuits for the VHF region, careful design and construction practices must be utilized in order to obtain stable and repeatable gain. Here are a few thoughts that may improve the ...

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FCC callsign with incorrect group letter
Accepted answer
8 votes

When the FCC issues your first call sign to you, they do not look backwards through their list of assigned call to see if there are any unused calls that they can reassign. Instead, they use a ...

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Using a common-mode choke on symmetrical antenna system
0 votes

Any imbalance in the source, the transmission line or the load can give rise to common mode currents. I make this point because we often see only the antenna (the load) as the culprit when in fact the ...

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Deep-cycle marine battery life question
Accepted answer
4 votes

When you parallel batteries, the combined reliability generally becomes less than the least reliable battery. In reliability engineering, this follows the equation: $$R_S=R_1*R_2*R_3 \tag 1$$ where $...

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Capacitive hats on wire dipoles?
5 votes

A capacitance hat used on a shortened antenna ($\le$ 1/8 λ for verticals and $\le$ 1/4 λ for dipoles) converts a largely triangular current distribution with the maximum current at the feedpoint, to a ...

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What are the effects of different feed-line incidence angles?
3 votes

When the coaxial cable is in the near field of a center fed, 1/2 wavelength dipole and it does not run perpendicular to the antenna, it is subjected to imbalanced near field currents. The coupling ...

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Wire dipole antenna proving ground / test bench
4 votes

Under ideal conditions you should strive to keep all conductive materials that are not part of the antenna system out of the near field of the antenna. This generally means non-conductive supports. ...

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Effective area of a dipole
5 votes

The preferred term is effective aperture. Effective aperture is defined as: $$A_e=\frac{\lambda^2}{4\pi}G \tag 1$$ where $\lambda$ is the wavelength of operation and G is the linear gain of the ...

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The right antenna size
3 votes

There are already a couple of nice answers to your question. I thought I would add a little more context - no need to vote for this as it is tangential to the question. A 1/2 wavelength (1/2 $\lambda$...

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Are there formulae to calculate capacitance and inductance of an antenna?
7 votes

A couple of minor comments on terminology. It isn't so much the "internal" impedance of the antenna but it is typically the "feed point" impedance that is of concern. This is the impedance seen where ...

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Efficiency of short dipole receiving antenna
8 votes

The efficiency of any antenna has a direct impact on the gain of the antenna. The gain of the antenna equally effects transmit and receive - a characteristic known as reciprocity. The highest gain ...

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Learning RF electronics
Accepted answer
4 votes

I am always happy to hear of someone that is trying to better their understanding and education. Congratulations and welcome. I agree that it is nice to have someone to personally talk with but let's ...

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Help with ZaStone D900
1 votes

The radio you received is a UHF DMR HT. If you have a DMR repeater in your area, you will be able to do some testing of the radio. You can locate a repeater by visiting RepeaterBook. The first step ...

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What kind of power plug does the ICOM IC-7300 need?
4 votes

A new IC-7300 comes with the power harness that plugs into the radio. The other end is connectorless so you can adapt it to your power supply using lugs, PowerPoles, stripped ends, etc.

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Twisting copper wire for a less-flexible DIY antenna
Accepted answer
4 votes

Your thought processes are on track - the primary electrical impact is on the RF resistance of the wire. Twisting the wires effectively creates a larger wire diameter with more surface area. The ...

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When was the first radio transceiver (transmitter/receiver) built, and by whom?
4 votes

This is tough to nail down since even the term transceiver is subject to interpretation. It is also often the case that a given answer may only be applicable for a specific geography. But with those ...

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Lightbulb as an SWR detector?
4 votes

Mainstream hams first started to appreciate SWR in the 1940's. In that era some of the first SWR meters started to come on the market. But their accuracy and frequency range was quite limited. Toward ...

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Is a copper J-Pole antenna better than a Slim Jim for transmitting?
5 votes

The slim jim antenna has no more or less gain than a J pole antenna - despite many Internet claims to the contrary. Any perceived difference in gain is likely due to CMC (common mode current) since ...

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Radio Range vs. Frequency
6 votes

This is an interesting question and while we may not be able to get to an exact answer, we can certainly explore the issues to consider. First we start by calculating a primitive link budget. The ...

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vertical 40m antenna takeoff angle
3 votes

If you model this antenna, it does predict a 22° takeoff with the radials 8 feet off the ground. Doubling the height would change the take off to perhaps 21°. You may wish to consider a good current ...

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True near field distance for a short monopole antenna?
Accepted answer
1 votes

The general formula for reactive field does not incorporate height, but rather maximum dimension of the antenna: $$R\approx 0.62\sqrt{\frac{D^3}{\lambda}} \tag 1$$ where D is the maximum dimension ...

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Non-life-threatening emergency in the US?
6 votes

Because the situation does not rise to the level of "imminent threat to life or property" you would not be permitted to "use any means neccessary" to carry out your communications. As a result, you ...

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