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 Interested in a cheap way to send multiple signals on the am broadcast band and maybe pal or DVB-T for under $20
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 Return to top of page · Post #: 1 · Written at 2:32:37 PM on 11 May 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

I have been using the RTL SDR dongles for receiving signals, mainly satellites
I have one pressed into service for grabbing the digital signals form the Russian Meteor M2 weather satellite, but also for use at work with our RTK systems and of course amateur radio.

I have been reading about a USB to VGA converter, hack that will allow transmission up to 1.8 GHz , with lots of harmonics, so you will require filters, but you can transmit DVB-T, GPS, WFM , AM, UMTS (4G)

I just ordered two at $11.00 each, should see them next week.

Here are some links
I like this idea. https://hackaday.io/project/21145-am-band-voice-frequency-marker
i built a two valve modulator for my broadcast receivers and it works very well, but I like the looks of the project above.

A bit more info here https://www.rtl-sdr.com/?s=FL2K


 
 Return to top of page · Post #: 2 · Written at 4:25:00 PM on 11 May 2018.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1378

Another thread that didn't indicate it was unread.


 
 Return to top of page · Post #: 3 · Written at 6:58:33 PM on 11 May 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

Sorry the work computer appeared to have spat the dummy, it didn't appear to have sent, as it just sat there, I refreshed and I gather it resent.


 
 Return to top of page · Post #: 4 · Written at 3:05:32 AM on 12 May 2018.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6347

No harm done. I've placed some text in the original thread so at least it can be cleared as a 'read thread'.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 5 · Written at 8:23:46 AM on 12 May 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

Thanks Brad.


 
 Return to top of page · Post #: 6 · Written at 8:05:13 AM on 17 May 2018.
Flukeoneseventyfive's Gravatar
 Location: Laidley, QLD
 Member since 16 September 2015
 Member #: 1799
 Postcount: 109

So.
No interest.
I received the adapters on Tuesday.
easy to configure.
I connected the output to the Stromberg Carlson that I just got working, Had a badly damaged choke, that I rewound.
But back to the adapters.
I ran the file from the terminal, using Ubuntu.
and it works so well, It is transmitting a voice that announces the frequency, right across the am broadcast band, that is it is transmitting a signal every 10 kHz at the same time, with an announcement for each frequency.
I initially ran the US files and tuning the radio, every 10 kHz there was the voice announcement of the frequency, I have generated a file for 9 kHz for use in Australia.

it is great for a quick check of the alignment of the LO.

I had it connected to the radio and there was no matching, no filters and it was straight from the VGA socket.
I did not hear it from the other radios, in the room, I tried a quick check on the HF spectrum and did not see a rise in the noise floor
on any of the amateur radio bands, or out side of the MW broadcast band.
I will check with the spectrum analyser in the next few days and also check the power output level, it is a 75ohm output.
want to try the DVB-T and PAL configurations and see how they work, might be an easy way for test patterns for television.
I think I will need a few band pass filters for those tests, as there are a lot of harmonics generated, to transmit at Higher VHF and UHF frequencies.
it could be a good general test box if paired with a raspberry or orange Pi, covering MW broadcast, Shortwave and television modes, all in a small case..


 
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