Linked Questions

23
votes
5answers
10k views

How can I protect equipment against a lightning strike?

A lot of aerials (almost by design) would be rather good attractors of lightning. What steps do I need to take in the field to keep my gear safe against a lightning strike? I'm presuming the obvious ...
3
votes
2answers
119 views

Interpreting (noise) signals from a small untuned shielded loop

This a follow up from this question: QRN: How to chase down a solid S9 noise floor on 40m only Focusing on how to interpret the signals received with an electrically small, untuned "shielded loop&...
2
votes
4answers
3k views

Voltage vs. Current Balun for Dipole

I'm a new radio amateur setting up a half-wave 10-meter inverted vee antenna fed by 50 ohm coax. I understand that the inverted vee lowers the normal 72 ohm dipole closer to 50 ohms, so I only need to ...
1
vote
2answers
193 views

Loop Antenna Construction

I have a loop antenna. When I connect the probe from my oscilloscope, does the probe also act as an antenna? If so, how should I fix that? I read about feeding technique, but I still do not ...
14
votes
4answers
13k views

Where are the baluns for VHF and higher? How can one be made?

In another question, commenters recommended that I look into adding a 1:1 balun to a dual-band dipole to eliminate the feedline as a radiator. As I understand it, a 1:1 balun also functions as a choke,...
3
votes
2answers
48 views

Should the earth rod be incorporated in the total length of an RF grounding system?

I have installed a grounding system just outside my radio shack and was careful to avoid a quarter wavelength or multiples thereof (for single band use), or anything in total length that is close to ...
1
vote
2answers
172 views

Troubleshooting 5BTV antenna

I have a Hustler 5BTV antenna i resurrected after a previous monopole succumbed to birds. It is giving me a world of trouble trying to get it tuned for resonance. For those not familiar with the ...
12
votes
2answers
4k views

Is there an optimum Antenna Feedline Length for mobile installations?

I bought a ham radio antenna mounting kit for my car that includes ~16' of coax. One end has a trunk lip NMO antenna mount, the other end has a re-solderable PL-259. I asked the sales person if it is ...
2
votes
4answers
7k views

How do you construct a 1:1 balun?

I have been researching how to construct a 1:1 current balun. I have a few questions and am looking for feedback on what I plan to do. First, I want to use the balun from 10m to 160m at 100w. I plan ...
3
votes
5answers
1k views

Do chokes at the antenna feedpoint stop the coax from receiving signals as well, or just transmitting?

It seems common knowledge that a choke at the antenna feedpoint stops the outside of the coax shield from radiating when transmitting into the antenna. But what about stopping the outside of the coax ...
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' ...
6
votes
2answers
3k views

How to measure a balun for effectiveness?

It seems there are almost as many "balun" designs as there are web pages about "baluns". There's lots of accusations pointed in all directions ("design Z isn't a balun OR a choke", "design Y is ...
0
votes
2answers
202 views

2 meter coax cable balun dimensions for use with a ground plane?

I have a commercially manufactured ground plane antenna for 2 meters. It will be fed with about 150 feet of RG 8/U . I've seen pictures of a coil of the feed line going to a 2 meter ground plane; this ...
3
votes
1answer
118 views

Do these magnetic field measurements of end-fed and center-fed half-wave dipoles corroborate measurements made by antenna experimenters?

Using a sensor and procedure discussed in my article, I made the following plot comparing the magnetic field strength along a 30m-band half-wave dipole fed at center and one end. Key points include: ...
4
votes
2answers
235 views

Dipole increased CM current using choke balun

My 20 meter inverted vee dipole is fed with 56 feet of 50-ohm coax. The SWR measures 1.2 at the center of the band. According to http://arrl.org/grounding a balanced antenna doesn't need a ground, so ...

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