Search results for: kn0ck

Testing the RTL-SDR on Windows 10 reader Marty Wittrock has written in to let us know that he has been successful in getting his HF modified “KN0CK” RTL-SDRs (and by extension standard RTL-SDRs) to work with Zadig and HDSDR on a PC running the Windows 10 technical preview on a VMWare image.

We decided to also test RTL-SDR compatibility with other common software on our own Windows 10 system. We tested SDR#, SDR-Radio, CubicSDR and Unitrunker and found them all to work fine with no problems either. Finally, we also tested the Airpsy and SDRPlay on Windows 10 and found no problems with those devices either.

HDSDR Running on Windows 10
HDSDR Running on Windows 10

An interesting RTL-SDR direct sampling modification

Over on the Reddit RTL-SDR discussion board user pksato has posted an image of his direct sampling modified RTL-SDR dongle. His mod includes a simple common base amplifier with 9dB gain, an impedance transformer with calculated output impedance of 50 Ohms and a 5V power filter.

The direct sampling mod allows you to modify your RTL-SDR to receive HF frequencies, without the need for an upconverter. It requires a hardware mod that can be as simple as soldering a wire to one of the RTL2832U pins, but for improved results you will need filters, impedance transformers and amplifiers. There is more information about direct sampling here.

More information and images about pskato’s mod can be found on the Reddit thread.

We also note that amateur radio hobbyist KN0CK (aka Marty Wittrock) sells direct sampling modified dongles that are modified in a similar way to pskato’s mod (circuit placed on top of the RTL-SDR PCB). His products can be found at

Direct Sampling Modified RTL-SDR.
Direct Sampling Modified RTL-SDR.
Direct sampling mod with amplifier circuit schematic by pskato.
Direct sampling mod with amplifier circuit schematic by pskato.

Roundup of Software Defined Radios

New software defined radio (SDRs) products are popping up every few months these days so we thought we'd compile a big list of available SDRs as there are a few people who were bitten by the RTL-SDR bug and are now looking to upgrade.

For each SDR we compare the cost, frequency range, ADC resolution, maximum instantaneous bandwidth, whether or not it can TX and if it has any pre selectors built in. Here is a quick guide to what some of these metrics mean.

Frequency Range: The range of frequencies the SDR can tune to.
ADC Resolution: Higher is better. More resolution means more dynamic range, less signal imaging, a lower noise floor, more sensitivity when strong signals are present and better ability to discern weak signals. Some SDR's give their resolution in ENOB which stands for effective number of bits.
Instantaneous Bandwidth: The size of the real time RF chunk available.
RX/TX: Can the radio receive and/or transmit.
Preselectors: Analogue filters on the front end to help reduce out of band interference and imaging.

* - Denotes top choice for high value

General Use Software Defined Radios

We define general use SDRs as ones with a wide frequency range and with no focus on any specific frequency band.

R820T RTL2832U a.k.a RTL-SDR*


Cost: $10 - 22 USD
Frequency Range: approx. 24 MHz - 1766 MHz (below 24 MHz available on V3 dongles)
ADC Resolution: 8 Bits
Max Bandwidth: 3.2 MHz / 2.4 or 2.8 MHz max stable.
TX/RX: RX Only
Preselectors: Uses tracking RF filters on the R820T2 chip.
Release Date: August 2016

The RTL-SDR is still the best 'bang for your buck' software defined radio out there. While it was never designed to be used as a general purpose SDR in the first place, its performance is still surprisingly good. If you're on a budget or are just starting out with SDR or radio this is the one to get. (Link)

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Integrated RTL-SDR HF Upconverter

Over at KF7LZE’s Blog a post about an upcoming integrated HF upconverter using tiny surface mount components has been posted. It is made by Marty KN0CK and will be for sale on KF7LZE’s site soon.

Marty KN0CK developed a very interesting v1.0 HF converter based on surface mount technology that fits inside the casing of an RTLSDR tuner dongle. He’s recently sent me schematics for the revision, which should offer even better performance.

Cropped HF Upconverter Respin 7

Check out the rest of the post here.