Search found 223 matches

by snn47
Wed Nov 04, 2020 7:54 pm
Forum: Antennas
Topic: Mini Whip Mod For VLF
Replies: 2
Views: 880

Re: Mini Whip Mod For VLF

Hello Bruce, I am wondering about the benefit of using an isolated BNC connector, because Coax cable and connector are asymetrical systems. Even if the output connector to the receiver is not grounded, the outer shield of the antenna input of any receiver would be grounded, except for battery powere...
by snn47
Wed Nov 04, 2020 7:49 pm
Forum: Troubleshooting Help
Topic: Can a ground loop damage an RTL SDR?
Replies: 1
Views: 581

Re: Can a ground loop damage an RTL SDR?

I try to answer the questions as I understand them. Yes all weird things can happen, or you had lightning strikes somewhere close by and secondary effects effected your AC which can kill some devices, while others survive A power supplies AC-In should be isolated from the AC-out. Some PS AC connecto...
by snn47
Fri Oct 30, 2020 9:44 am
Forum: Other SDR Devices
Topic: Modify RTL-SDR Wideband LNA for HackRF TX
Replies: 3
Views: 788

Re: Modify RTL-SDR Wideband LNA for HackRF TX

There are many prebuilt and modules for amplifier available. The price increased with frequency, bandwidth, amplification and power out. There are not only only harmonics to consider, but also Out Of Band (OOB) emissions, which can produce interference. The severity of OOB emissions depends among ot...
by snn47
Fri Oct 30, 2020 9:33 am
Forum: Antennas
Topic: When antenna isn’t in use best practice
Replies: 4
Views: 807

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: 15303

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: 943

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: 948

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: 1859

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: 1569

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: 1569

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...