SDR dongle HF mod on ebay

[wb4jfi at knology.net]

There are articles for free about how to inject signals directly into the dongle A/D converter on the various RTL modules.  I think the A/D samples at around 25MHz, so if you do that, you can get some HF, about 0-12MHz.  THat may be what is going on here, since they say that all you need to use one toroid.

Of course, it’s still an eight-bit A/D, so your dynamic range will REALLY suck.  It won’t be anywhere near the $1,200 SDR radio that they claim.  If you don’t mind constantly changing an input attenuator, it might be usable.  Since you are bypassing the RF chip on the dongle, you no longer have access to the RF AGC or manual RF gain control built into that chip.

I’m not sure how they get 0-30MHz coverage, other than maybe undersampling, but maybe my understanding is off.  Of course, several other of their claims are far-fetched, so maybe that one is as well.

I have thought about hacking up one of my dongles like the above, just to see how bad it is...

Try it, you might like it... or not.
73, Terry, WB4JFI


From: Alex Fraser 
Sent: Saturday, December 28, 2013 4:32 PM
To: Tacos 
Subject: SDR dongle HF mod on ebay

I saw this sale of a CD containing plans on how to modify a USB receiver dongle to receive HF without an external converter.  Any one played with this?  Any comments?
http://www.ebay.com/itm/HF-SWL-SDR-RECEIVER-DIY-/291043350290?pt=US_Ham_Radio_Transceivers&hash=item43c3891712

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