Search found 260 matches

by snn47
Fri Oct 30, 2020 9:33 am
Forum: Antennas
Topic: When antenna isn’t in use best practice
Replies: 4
Views: 1985

Re: When antenna isn’t in use best practice

@VE3AER congrats for beeing lucky at your QTH, but this does not mean other people will be that lucky. Even if there is not a direct lightning hit into an antenna, there are also secondary effects by lightning, which are spikes induced on wired connections. These can be equally sufficient to destroy...
by snn47
Fri Oct 30, 2020 9:03 am
Forum: RTL-SDR Discussion
Topic: Can I use the SDR very close to the RF source?
Replies: 12
Views: 17748

Re: Can I use the SDR very close to the RF source?

There is a similar discussion ongooging which provides additional information
see viewtopic.php?f=1&t=6158 To near to the RF source?
by snn47
Tue Oct 27, 2020 3:01 pm
Forum: RTL-SDR Discussion
Topic: To near to the RF source?
Replies: 4
Views: 1977

Varying voltage with antenna type and location on antenna

There is no simple answer to your questions, it depends on many factors and not how close you are to the antenna. The voltage on an antenna changes with antenna type, it's voltage distributions and therefore the position. The voltage changes therefore with where you come close to or touch an antenna...
by snn47
Sun Oct 04, 2020 9:30 am
Forum: Signal Identification Help
Topic: About 40 signals around 430Mhz in France (audio sample)
Replies: 3
Views: 4103

Re: About 40 signals around 430Mhz in France (audio sample)

@username 1) its some Weird Amateur Radio stuff 2) its "just" noise To 2) Noise would not have distinctive frequencies, be not repetivie and would be diffuicult to generate with the strength you see here. To 1) Why is it weird just because it is in the 70 cm Ham-band? The 70 cm is in part shared wor...
by snn47
Sun Oct 04, 2020 8:47 am
Forum: Antennas
Topic: best v-dipole height for noaa satellites
Replies: 2
Views: 2784

variation of (Freespace) antenna pattern due to refelcting ground/objects

The effective antenna pattern is not just the pattern of the antenn (-goup or -array) in freespace, but the combination of all rays reflected on reflecting surfaces (not just ground, but also walls. Above a reflecting surface the 8 shaped freespace pattern of Dipole will therefore have lobes and not...
by snn47
Sun Jul 19, 2020 10:52 pm
Forum: Antennas
Topic: Big Loop Antenna
Replies: 4
Views: 2657

Re: Big Loop Antenna

For Aluminum and Stainless Steel you can find an overview here. https://www.albanycountyfasteners.com/blog/stainless-steel-and-aluminum/ . There are different types of Stainless Steel and Aluminum, which have different percentage of other metals in it, which may influence corrosion too. I cannot mak...
by snn47
Sat Jul 18, 2020 12:31 pm
Forum: Antennas
Topic: Big Loop Antenna
Replies: 4
Views: 2657

Re: Big Loop Antenna

How were the Aluminum Fascia pieces connected to each other? Unless the Aluminum Fascia is heavily corroded at the connections, maybe just redooing a limited numbers of connections might be a solution for you. Running both in parallel should increase capacitance unless you connect the cooper and the...
by snn47
Mon Mar 09, 2020 9:43 pm
Forum: RTL-SDR Discussion
Topic: Upconverter vs. Direct Samling?
Replies: 3
Views: 7159

Re: Upconverter vs. Direct Samling?

Hotpaw I would say it depends on how you define the direct sampling setup, you use e.g. 8, 10, 12 ... Bit AD, what type of preamp if you use one, are filters used and which type HP,LPW, BP vs. the performance specs of the upconverter and by the SDR after the upconverter, you assume 8, 10, 12 ... Bit...
by snn47
Mon Mar 09, 2020 6:18 pm
Forum: RTL-SDR Discussion
Topic: Measuring VSWR
Replies: 3
Views: 7301

VSWR is important for transmitter

I wonder because I think the antenna I bought can't cover all of the HF and VHF frequency. It depends on your definition of cover. There is no antenna I know of that will support such a large range of frequency/wavelength and is matched for all frequencies. There are active antennaes that have smal...
by snn47
Mon Mar 02, 2020 11:14 pm
Forum: Antennas
Topic: Static shock while connecting ground-wire to radio?
Replies: 14
Views: 16292

Static electricity built up over time

I guess you are experiencing static electricity built up over time. If you have a coax cable then the capacity, wich will vary with cable type and length, the static electricity will accumulate over time. Did you have a thunderstorm building up in your area when you experienced this? The static elec...