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11
votes
2answers
4k views

How to reduce RF in the shack when using vertical HF antenna (no radials)

What can be done to reduce RF in the shack (riding back along the coax) when using a vertical 10M antenna (without radials due to space constraints)? The antenna is an IMax-2000 at 32' elevation (20' ...
9
votes
2answers
2k views

What is the largest gauge (thinnest diametre) wire I may use as an antenna?

A follow-up to Good wire for wire antenna? I'm QRT at present - thanks to fooling around with just a couple of diodes and PVC capacitors instead of a well-regulated supply. The antenna I used earlier ...
4
votes
3answers
99 views

What should be in a one hour class about Radios in Boy Scouts [closed]

I have been tasked with teaching a one hour class to adults who lead Boy Scout troops about "Radios in Scouting". What should I teach them? Possible subjects include: Teaching the Radio Merit Badge ...
16
votes
4answers
22k views

What bands and modes will give me voice at 3,000 miles?

I pursued Amateur Radio primarily for local emergency communications and as part of my electronics education. My only radio right now is an inexpensive 2m/70cm HT which is good for local weather ...
6
votes
3answers
8k views

How can I construct a practical loop antenna for 2m band?

How can I construct a practical loop antenna for 2m band to use in a fox hunt? Is it even possible to construct a hand-held antenna for the 2m and 70 cm bands? I tried to calculate the dimensions ...
14
votes
4answers
2k views

How can RF exposure hurt you?

In studying for the exam, one question came up about RF Exposure. G0A 07 What effect does transmitter duty cycle have when evaluating RF exposure? My ...
7
votes
4answers
1k views

Battery sizing for power draw

Note that this question isn't about battery capacity, at least not per se. I have a 100 Watt mobile transceiver. At 12 V and assuming 50% efficiency, that means it draws a little under 20 Amps at full ...
9
votes
1answer
2k views

Digital-mode signal reports

When operating analog voice, we give a qualitative (or possibly just arbitrary) signal report, 'scoring' the signal either out of a maximum 'five by five', or a maximum '599'. How do you report the ...
9
votes
1answer
101 views

Can two diodes be parallelled in RB to get double the capacitance?

It's a fact of life that air-gang capacitors, are increasingly more difficult to come by - having been superseded by the far more compact varactor diodes. My part of the world components such as the ...
35
votes
7answers
37k views

Using a balun with a resonant dipole

I am preparing to construct a resonant, center-fed, horizontal dipole. I have seen people use baluns at the feedpoint of the antenna, and some people swear by them, but I have never gotten a ...
9
votes
1answer
831 views

What is the correct procedure to beam long-path?

I'm new to directional beam antennas, and saw that K9W Wake Island DXpedition was working 10 meters "long-path" at 1230z, or 6:30a.m. in Texas. This was late enough for the sun to be coming up, but is ...
4
votes
4answers
894 views

Is string trimmer line suitable for supporting antennas?

In searching for suitable materials for a wire antenna, I found a few mentions of using string trimmer line to hold up each end of the antenna. This would be a nice option as it is readily available ...
6
votes
1answer
2k views

Can a Yaesu FT-7900R be physically connected to both KPC-9612+ ports?

The Yaesu FT-7900R has a single data port (mini DIN 6-pin) for 1200 and 9600 bps TNCs. Page 10 of the manual states: In accordance with industry standards, the signal levels, impedances, and ...
9
votes
3answers
21k views

How would I modify a satellite dish to transmit and/or receive to a Baofeng UV-5r plus? ( A handheld transceiver) If it's possible

I have an old satellite dish just lying around and was wondering how to hook it up to my baofeng uv-5r plus.
3
votes
2answers
348 views

Do electronic ballasts for fluorescent tube lamps cause HF interference?

I am going to build a new home and I would like to use energy-saving fluorescent tube lamps in some rooms. Manufacturers are currently pushing electronic ballasts a lot in favour of switchstart series ...
6
votes
2answers
753 views

Is there a digital multimeter that is more interesting for a ham than a run-of-the-mill model? [closed]

My 22-years old Fluke 79 died on me today... Luckily, it was a quiet dead, but nonetheless it left me a bit emotional... So, I am in urgent need of a replacement digital multimeter. This made me ...
10
votes
2answers
4k views

How much RF energy do trees and branches absorb?

For the 20m - 10m and 6m bands, will having my dipoles below the tops of trees (I live in redwood forests) drastically affect the RF power out or radiation patterns of my dipoles if I can still get ...
4
votes
1answer
2k views

Installing cuSDR on Ubuntu 13.04

I've been trying to install cuSDR64 on Ubuntu so as to have a 4-receiver 4-display SDR setup. I found the Windows repository on svn here. But, it gives an error (check this question). The cuSDR home ...
17
votes
2answers
3k views

Ham radio above 275 GHz

I see on the allocation chart all modes and frequencies are allowed above 275 gigahertz. Has anybody experimented with this? Are there interesting things you can do on these extremely high frequencies?...
3
votes
3answers
1k views

What is the best battery type for replacing old NiCds in a Icom 2AT?

I broke out my 2AT after a number of years. The nicads in it are dead. What kind of replacement inserts should I be looking for? Nicads are so 1980s. What is the current 'best' technology?
1
vote
1answer
1k views

Where to find a list of echolink nodes in a specific country

I google search "Echolink Nodes in Germany" and no results show of nodes which are in Germany. I search repeater book, but it seems like it only has North American nodes. Is there a good source where ...
2
votes
2answers
381 views

Horizontal dipole for a 80 foot span?

I have the K1JEK Cobra UltraLite and it works exceptionally well. However that was when I had a larger yard. Moved to a house with a smaller lot and now can't use the JEK Cobra (max span between trees ...
9
votes
3answers
3k views

Why do so many HF transceivers use a UHF connector?

Just looking around at various rigs online for a fiend. Lots of them look really attractive TS-480, K2, K3, FT-450D, FT-950, IC-78, FT-897 to name just a few... These rigs are mostly HF, albeit some ...
8
votes
1answer
744 views

Do I need a SWR meter for a basic 2 meter antenna?

I have a 5 watt 2 meter handheld transceiver and want to build a helmet with an antenna, microphone (with VOX enabled) and earpiece for the radio. For the antenna part, I just want to do something ...
22
votes
2answers
4k views

How do Handheld antennas work without ground?

Dipoles have the 2 wires going to each leg of the antenna completing the circuit. Big AM towers use the second wire as a ground plane But how to handheld rigs transmit and recieve with just one wire ...
6
votes
8answers
6k views

VHF/UHF digital single-frequency repeater without duplexers?

Some digital voice protocols are time slotted (TDMA), i.e. the transmitter of a station is not on all the time, and multiple stations may transmit digital voice on the same frequency at the same time ...
9
votes
2answers
3k views

What causes ground losses in a HF antenna system?

This applies to mobile and fixed installations. What are ground losses, and how can they be minimized? It seems to involve proximity to the ground, but what is the mechanism that causes loss? Does ...
9
votes
1answer
151 views

Antenna modeling on non-uniform terrain

I'm interested in modeling the radiation pattern of wire antennas for hf before I invest the resources necessary to erect the antenna. I'm familiar with tools such as 4nec2, but from what I can tell ...
5
votes
1answer
4k views

What does TX/RX Exchange refer to?

I am using the Aether logging software and it has two fields I do not understand: TX Exchange and RX Exchange. I know TX and RX refer to transmit and receive, but I'm not sure what to populate in ...
5
votes
1answer
355 views

Where is the Multi-Drop XKISS / BPQKISS spec?

In packet radio, AX.25 is a fairly common layer-2 protocol. Many TNCs implement AX.25 in firmware, so the operator interfaces to the TNC with a serial port, using the TNC's firmware from a shell-like ...
8
votes
5answers
2k views

Is Morse code a requirement for ham licensing?

As I recall, it used to be in the U.S. that the ability to read and send Morse code over CW was a requirement for an amateur license (and was tested, I believe). Is that still true in the U.S.? If ...
5
votes
2answers
691 views

Power dissipation in transmission lines?

I was wondering, does the impedance of a transmission line have any effect on the power it dissipates? I'm familiar with the fact that an impedance equal to the load will provide maximum power ...
8
votes
3answers
277 views

How do club codes stay secret?

To use auto patch, IRLP or other special repeaters, you need the club code from the local club I am part of, which is a DTMF code. But I was thinking, DTMF can't be very hard to decode, and if ...
9
votes
4answers
15k views

2m or 70cm FM mobile radio for digital mode operation

Are there any 2m and/or 440cm FM mobile radios that have audio inputs for supporting digital modes, like PSK31 or SSTV? I have a Rigblaster that I use with my HF radio so I could get a mike cable and ...
8
votes
3answers
2k views

Will anodizing or powder coating or wetcoating (painting) antenna elements affect performance?

I want to put up a small tower and beam on my roof, but I don’t want the aluminum to “stick out” and want it to be unnoticeable as possible. I would think black anodizing would be the best solution ...
0
votes
2answers
326 views

Can we build an open source firmware for the X1M qrp transceiver [closed]

There is a chinese transceiver the X1M, look at x1m.wikia.com and on google. That is basically an SDR but no one has worked to build open firmware for it yet. i think we have a great chance to build ...
8
votes
4answers
2k views

Has a vehicle magnetic antenna mount ever caused a road accident?

Some people believe that mag mount magnets lose their effectiveness over time, eventually causing a dangerous situation as the antenna could rip loose from the vehicle and become a projectile or ...
0
votes
2answers
1k views

Baofeng UV-82 Dual-Band (2m/70cm) HT Channel Clear Error

After clearing channels (menu option #28) to free them up for use, I have found that they become completely unusable for future frequencies. Switching back from VFO to channel mode and trying to go to ...
6
votes
2answers
244 views

75 watts and a mag mount antenna

I am planning to get a Yaesu FT2900R 2 meter rig for my 2001 Honda Accord. With my 5w FT60, I wasn't able to reach repeaters that were any more than 10 miles distant (I live among mountains.) How ...
12
votes
4answers
1k views

What is generally considered “too much” power for JT-65 on HF?

Recently, I have begun experimenting with JT-65A, mostly on 20 meters. I usually run about 5 watts with that mode, since I know that JT-65 is a weak-signal mode. Is that still too much power? What is ...
11
votes
6answers
2k views

Does iron ore in the ground affect my signal?

Mineral content in the ground varies from one place to another. I've visited places where the ground & waters were an orange-red shade from the high iron content; not good for trees either. This ...
11
votes
2answers
337 views

What would propagation look like on Mars?

If we could get a few HF stations on Mars, what would the propagation look like? Thought shamelessly copied from this blog.
6
votes
1answer
606 views

FM radio in car gets interference from APRS beacon

The FM broadcast radio, factory installed in my car and usually tuned to 88.6 MHz, gets some interference from the 5W APRS transmitter on 144.800 MHz. It sounds like if the sensitivity of the ...
1
vote
2answers
1k views

Kenwood TS-590S VGS-1: Voice keyer does not transmit unless VOX is enabled

I have a Kenwood TS-590S with a VGS-1 voice guide/storage module, which I use in multi/multi contesting operations for voice keying (calling CQ). There's one drawback - it seems to only transmit ...
13
votes
2answers
1k views

Direction finding: How to find a stuck FM transmitter on 70cm?

There's a blank carrier on a 433 MHz FM voice frequency here. How should we go on about finding the transmitter's location? Practical procedure? Could be somewhere downtown.
8
votes
4answers
10k views

How to improve VHF/UHF Baofeng UV-82 HT reception in vehicle

I have a Baofeng UV-82 dual-band (2m/70cm) HT with an SMA male connector for the stock "rubber-ducky" antenna. I would like to use it in my vehicle. I would like a high-quality magnetic mount dual-...
6
votes
1answer
750 views

Kenwood D710: loud fan noise when used in the shack

The fan in the Kenwood D710 mobile radio is turning on on every transmission, including the periodic APRS beacons. This happens even when there is no actual need for spinning it, and is very annoying ...
5
votes
1answer
1k views

How to calculate power loss between radio and antenna

I have a 5W HT that only kicks out about 1W by the time it hits my antenna (which I understand is the norm). How do I go about calculating power loss in various equipment?
3
votes
2answers
453 views

Understanding “ground” in ham radio

What is a good explanation of the different "ground" types that hams deal with? Specifically: grounding an antenna mast/tower (outside, lightning prevention) grounding transceiver/equipment (inside ...
6
votes
2answers
2k views

What are CQ/ITU zones used for?

There are already questions about the definition of CQ zones and ITU zones, but there is no information about what these zones are used for (and Google brings up various maps but no explanation). (Is ...

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