Search found 48 matches

by franko
Sun Feb 10, 2019 9:48 pm
Forum: SDRplay related
Topic: Behavior of AM broadcast images in longwave spectrum?
Replies: 3
Views: 708

Re: Behavior of AM broadcast images in longwave spectrum?

Thanks very much for the link to the paper. Since the broadcast images do move when the LO changes, that makes it clear that they are higher-order mixing products and not the result of intermodulation. In initial daytime experiments, I've found that by using both the RSPduo's MW notch filter and the...
by franko
Sun Feb 10, 2019 8:03 pm
Forum: SDRplay related
Topic: Behavior of AM broadcast images in longwave spectrum?
Replies: 3
Views: 708

Behavior of AM broadcast images in longwave spectrum?

I'm scratching my head a little over the behavior that I'm seeing with AM broadcast images in the longwave spectrum, and would be interested in any help or ideas. I have an RSPduo attached to a Wellbrook ALA1530LNP mag loop antenna, controlled by SDRUno 1.24 on a Windows 7 PC. Normally the longwave ...
by franko
Fri Feb 01, 2019 7:19 pm
Forum: SDR Antennas
Topic: Antenna for LW
Replies: 11
Views: 2072

Re: Antenna for LW

Great lightning map website! You mentioned WSPR in your last post. I tried it out last light, heard several hams in Arizona and New Mexico on 630 meters. There was one log entry for K9FD in grid square BL11 (the Hawaiian Islands). In addition to WSPR, it seems as though there's a certain amount of J...
by franko
Thu Jan 31, 2019 8:05 pm
Forum: SDR Antennas
Topic: Antenna for LW
Replies: 11
Views: 2072

Re: Antenna for LW

Anytime thunderstorm activity is low. late summer, autumn and winter seem to be the best here in the eastern US. The QRN from lightning activity can travel great distances at longwave frequencies. You mentioned WSPR in your last post. I tried it out last light, heard several hams in Arizona and New...
by franko
Tue Jan 29, 2019 5:24 pm
Forum: SDR Antennas
Topic: Antenna for LW
Replies: 11
Views: 2072

Re: Antenna for LW

Overwhelmingly NDB's (Non directional beacons). You can investigate for yourself with the Maritime Radio Historical Society's low band KIwi SDR at http://198.40.45.23:8072/ It is connected to a Marconit T antenna. I could only find 4 active NDB's in California in the ClassAxe database. Thanks, I'll...
by franko
Tue Jan 29, 2019 6:51 am
Forum: SDR Antennas
Topic: Antenna for LW
Replies: 11
Views: 2072

Re: Antenna for LW

Better hurry, long wave season will end soon. Can you say anything more about what you hear, and when during the year you hear it? I'm unable to hear anything on LW due to very strong local MW broadcast interference, but am in the process of obtaining a low-pass filter. Interested in what might be ...
by franko
Sun Jan 20, 2019 5:28 pm
Forum: SDR Antennas
Topic: 60v p-p rf
Replies: 11
Views: 2301

Re: 60v p-p rf

I used the scope input and the antenna is a 900 ft wire grounded far end at lake, between 5 and 20 feet high, running approximately northwest. Like any loop its directional. About 3k ohm at MF/LF. DC loop resistance s about 50 ohm, mostly from wire, .03 aluminum welding wire. I have ground stakes a...
by franko
Sat Jan 19, 2019 8:17 pm
Forum: SDR Antennas
Topic: 60v p-p rf
Replies: 11
Views: 2301

Re: 60v p-p rf

I put a scope on my long antenna and it reads 60 volts peak to peak RF from local AM stations. As a new oscilloscope owner, I'm curious about the details of how you hooked this up. I know my scope has 1-megohm inputs, so for most RF devices including my antennas it's necessary to add a 50-ohm feed-...
by franko
Mon Jan 14, 2019 8:44 pm
Forum: General
Topic: Transmit-receive switches
Replies: 1
Views: 799

Transmit-receive switches

The adjacent thread "MFJ-1708B-T/R Switch Experiences" reminded me of a question I wanted to ask, but I thought it might be clearest to post a new thread rather than tag on to that one. Currently I have two SDRplay RSPduo units running continuously, each attached to its own magnetic loop a...
by franko
Sat Jan 12, 2019 7:53 pm
Forum: SDR Antennas
Topic: Loop antenna for SDR question
Replies: 5
Views: 3101

Re: Loop antenna for SDR question

Sorry for chiming in on the late side, but I have a Wellbrook ALA1530LNP loop antenna as well as a W6LVP loop. I've done a fair amount of side-by-side comparison with each connected to a separate SDRplay RSPduo, with them running simultaneously and monitoring the same HF FT8 band. Because of a stron...

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