Posts Tagged ‘up-converter’

KN0CK and KF7LZE RTLSDR for HF Back In Stock at!

March 11, 2014 Leave a comment

We’ve completed the next production run of Rev 5 direct-sampling RTLSDR with HF converters by KN0CK and they’re back in stock over at! We also have a limited number of Rev 4 converters, which use a 120MHz oscillator and mixer, back in stock as well.

Check them out at!

Rev 4 RTLSDR with HF Upconverter and Amplifier
Rev 5 Direct Sampling HF RTLSDR with Amplifier

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For Sale: The KN0CK and KF7LZE RTLSDR for HF Rev. 5!

January 28, 2014 1 comment

I’m happy to announce that Rev 5 of the KN0CK and KF7LZE RTLSDR for HF is now available for sale in its 5th iteration – now featuring Direct Sampling, while still keeping the familiar wide-band pre-amplifier! On account of the reduced parts count, we’re able to offer it at a discount over the previous version too. Yours for only $75.00 plus shipping!

Uncased Direct Sampling Receiver

Get yours at today!

Previously seen at

Coming Soon: KN0CK and KF7LZE RTLSDR Receiver Rev. 5!

January 6, 2014 2 comments

Updated: Now for Sale!

I’m proud to announce that in just a few days, in cooperation with KN0CK will be releasing Rev. 5 of the popular RTLSDR Integrated Upconverter with a brand new design and smaller form factor!

This new design will feature a lower price-point and is designed for operation in direct sampling mode for improved flexibility across the entire frequency range. It contains the familiar Mini-Circuits MAR 8 wideband amplifier, to deliver unprecedented weak signal performance when paired with a quality receiving antenna setup.

Available at NOW!

KN0CK HF Converter Rev. 4 is Released!

July 25, 2013 1 comment

The complete Rev 3 KN0CK HF Converter has sold out and been discontinued. That’s okay, though, because it’s been replaced with the KN0CK RTLSDR for HF Revision 4! This model incorporates a lot of the feedback from the community about the old stack – especially the expanded tuning range, since the new model can now upconvert from the 6m band (54 MHz) versus 30 MHz with the previous model. It’s even smaller and still manages to be easier to manufacture, too, and it retains the core Mini-Circuits pre-amplifier and 120MHz local oscillator frequency.

Receiver Closed Up

Receiver Opened Up1

It’s a pretty great performer, too.


It’s available for sale over at Easy-Kits for the same price as the Rev 3 converter.

If you’re more of a DIY type, you can also purchase one of the remaining unmounted Revision 3 Bare Board to build into its own enclosure or attach to a dongle you already own if it fits in the case. 

Coming Soon: KN0CK Rev B Integrated HF RTLSDR

May 1, 2013 7 comments

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!

This new iteration has a few major upgrades from the previous – an ESD protection diode on the input, and an optional Mini-Circuits MAR 8+ RF preamplifier which should really draw out some weak signals. Nice weather is coming up soon and once I have some free time, I’ll string up my long antenna – this should really pick out the weak shortwave signals I love hunting for.

Now Available! Limited Quantities – Sign Up at Easy-Kits to be notified when back in stock if sold out.

KN0CK HF Upconverter Fits Inside the USB Tuner’s Enclosure

February 19, 2013 10 comments

Marty KN0CK sent me some details to publish about his great looking miniature HF upconverter board for the RTLSDR, the HF Alchemy DVB-T Active HF Upconverter. It’s an incredibly miniature SMT board with an SA612 mixer and SMT oscillator, and with some very careful soldering the entire board fits inside the housing and draws its power from the tuner’s USB port. The design upconverts at 120MHz, which is well out of the FM band to reduce the possibility of interference from strong local stations. A 40 MHz low-pass filter on the input further reduces interference. Marty reports it works GREAT!

I also had the opportunity to test an identical dongle and it was very easy to use. It requires a PAL adapter, but most of these dongles need an adapter and this one wasn’t difficult to locate; the integrated form factor is excellent. It’s very sensitive, a bit more-so than my other tuner module even, and the integrated form factor is perfect. It would be very easy to purchase an active USB extension cable and locate this integrated SDR in a shielded enclosure at your antenna’s feed point for even lower losses and versatility.

Update 1/28/2014: We’re up to Rev 5!

Thanks for sending this in, Marty!

DIY SDR HF Up-Converter by WA7JHZ: Another good choice for your RTLSDR.

February 2, 2013 2 comments

Reader David Forsman, WA7JHZ, read the round-up of RTLSDR upconverter choices and sent me a photo and build schematic of one he designed which was featured in the January 2013 issue of QST, the ARRL‘s monthly magazine.

This circuit up-converts frequencies between 2.3 MHz and 43 MHz by 125 MHz (127.3 MHz to 168.0 MHz) for driving the Realtek RTL2832 quadrature decoder DVB-T device with Elonics E4000 tuner chip with USB 2.0 output. It also incorporates an input bandpass filter (BPF), diode limiter, RF attenuator, and amplifier.

The filter’s response curve:

David reported he’s built two of these up-converters with good sensitivity on 20 and 15 meters. I think I have all the parts except the crystal and coils to build this on hand, so this might be a good excuse to sting my antenna up again and try it out.  Thanks David for sending this in!

[Full size schematic]

Round-Up of RTLSDR Upconverter Choices

September 14, 2012 25 comments

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Updated 2/22/2014!

If you’d like your RTLSDR to be able to access very long wavelength bands, you’re going to need an upconverter. There are quite a few choices for an HF converter / up-converter are now available which use a mixer and crystal oscillator to shift incoming signals into the tuner’s frequency range. These range from pre-built boards, partially built kits, and plans depending on your skill level and interest. An assembled board or a partially assembled kit will set you back about $50-100; if you’re savvy you can probably make it for $10-20 in parts – if you don’t mind winding your own coils. Your mileage may vary.

If you have a plan, kit, or finished product you’d like to share – or if you know of one I’ve missed – send me an e-mail or leave a comment here!

1. There’s a new Ham It Up v1.2 HF upconverter for software defined radio produced by Opendous which has a large amount of documentation including layouts, and can be purchased mostly-assembled for only about $50. v1.2 makes some small improvements, including a 125MHz crystal instead of a 100MHz crystal to ensure there’s no interference from the U.S. FM Broadcast Band. It also features an input switch and an optional hardware noise source is an interesting, if possibly seldom used, feature. Ham Radio Science has a rather extensive review of the original revision and were pretty happy with it.

2. CT1FFU v5  HF converter is a brand new iteration of the long-standing design which was originally one of the first released. This model features an improved smaller PCB size, improved filtering and am improved ring mixer, and phantom power to eliminate a power cable when attached to certain compatible RTLSDR receivers. The LO is still 65.520MHz or 106.250MHz which might interfere with an FM Broadcast band in some countries, such as the U.S., but there is some filtering incorporated to eliminate that. The price is reduced to 55 Euro shipped worldwide with tracking.

3. Marty KN0CK has developed an incredible upconverter which fits inside the tuner dongle’s enclosure using all 0402 SMD parts. It’s a complete stack, including the RTLSDR tuner and hand-assembled integral filter and pre-amplifier using the Mini-Circuits MAR-8+ amplifier. Very powerful, great at picking out weak signals, and requires no external hardware or cabling everywhere – just hook up an antenna and go. Available for $75 US plus shipping (U.S. and International shipping available), this is a addition to your ham shack. Buy it over at Easy-Kits.

4. I’ve been using CT1FFU’s v3.1 dongleGerman retailer Wimo sells completed kits, which have been in stock even when CT1FFU’s own kits have sold out. A no frills HF up-converter, mine came assembled except for the SMA connectors. It’s one of the early generation upconverters but still offers solid performance. V3.1 uses a 106.250MHz IF.

Wimo also sells the FunCube dongle, if you don’t already have an SDR.

5. JA7TDO has produced the Soft66RTL, including an RTL2383u+R820T and an HF converter with a 50MHz local oscillator frequency in what looks to be a nice, 3D-printed case capable of receiving up to 30MHz, or 50MHz and above bypassing the converter.


6. JaniLab has started selling a derivative of the CT1FFU v2.0 on eBay for a bit lower of a price than some of the others. The older revisions work well, although with some more leakage than subsequent designs, and don’t have quite as fancy filtering or switching features.

Janilab actually offers several. There’s both this one with the DBM mixer, above, and another CT1FFU v2.1 derivative with an SPL mixer.

7. Janilab also sells another DBM mixer-based converter, with an antenna switch to bypass the conversion.

8. And if that wasn’t enough, they even rolled their own board and put an RTLSDR and an converter on the same PCB, with an integral antenna switch. This is incredible. Not cheap, though.

9. If you’re looking for a more rugged commercial solution, High Sierra Microwave has an upconverter (FCD-1-55-UC) with a 133MHz LO frequency and BNC terminals with an integral amplifier. I’m a fan of converters whose LO frequency shifts the entire HF range above the FM broadcast band in general and the shielded enclosure will definitely cut down on noise. Looks like it’s suitable for mounting outside at your antenna’s feed point, and it also looks like you’re going to pay for those features. I’d love to evaluate one of these if I could get my hands on one.

10. W9RAN developed a RANverter kit which was featured in the January 2013 issue of QST magazine, using a 125MHz local oscillator. It’s gotten a lot of great buzz on the Internet and offers good performance and even a little bit of conversion gain through the mixer. Unfortunately, he appears to no longer be offering it for sale. I did manage to get a set of boards and will be offering the W9RAN precision converter through eventually.

11. If you’re comfortable speaking  Dutch, or just with Google Translate, you can buy the Kit RF Converter for RTL SDR Sticks DC – 65 MHz. Unlike most other models, this one HF up-converter takes a BNC 50 Ohm antenna input and has an SMA 50 Ohm output with a 100 MHz oscillator frequency and built-in protection. This one also looks like a great starter kit with through-hole components and large coils and looks easy to build. You can also purchase the completed assembled kit in an enclosure, which also includes a power cable and SMA-MCX adapter cable. Looks interesting.

12. Kalle over at DGK Electronics has a great looking compact 100MHz HF converter designed to fit inside of a pre-made RF shielding box. It uses the ADE-1 mixer and an ASEM oscillator. It has some of the most complex filters and great filtering on the incoming power line, it probably performs very well. He describes the filters on his page, and there’s also a full schematic available. There’s a photo of a pile of boards, and he says there’s still some available, one might be left! DGK Electronics

13. David Forsman, WA7JHZ, sent me a photo and plans of his 125MHz HF up-converter with a diode limiter, attenuator, and amplifier all in one from plans featured in Jan ’13 QST magazine. Click through there to the article for a schematic and explanation for more details and a full schematic. Thanks, David!

14. Matt Dawson GW0VNR has a very interesting HF converter using more discrete parts than some of the other ones I’ve seen. It uses hand-wound transformers, an actual discrete diode mixer, and a Saronix oscillator running at 106.25 MHz. It uses a total of 23 parts and looks like it would be pretty easy to build. He doesn’t have any photos of the completed board, but does have a full schematic, overlay, transfer mask and Gerber files for the PCB. I’m pretty sure I have all the parts to build this one in my box as well. It looks interesting and simple. Check it out.

15. Radio amateur Paulino Sato has posted schematics and specifications for using the TA7358AP FM Front-End as an HF up-converter you can build yourself, using small coils wound on your own forms. It’s a bit of a commitment, but only has about 40 parts. The instructions are in PDF format. Download from me directly or the original is available on DropBox. The PDF contains PCB masks and silk screen layouts and a full schematic.

16. Over in the UK at the George Smart Wiki, we see homebrew plans by M1GEO using hand-wound coils with an SBL-1 mixer and 100MHz crystal oscillator. It has around 20 parts to assemble. These coils look like they could be hand wound on a dowel coil form, and the crystal and mixer are very large parts, so you could probably build this on perfboard without any trouble.

17. Bryce Salmi KB1LQC built a very rugged-looking clone of George Smart’s above with some modfiications dead bug style.

18. Romanian amateur Alexandru YO2LDK built a simple HF upconverter circuit using an NE602. This has an amplifier, limiter, regulated supply and 100MHz frequency like several of the ones pictured, but the circuit itself looks quite different. The amplifier stage is ahead of the limiter, which looks like this one is offering a constant gain versus the adjustable gain some of the others have offered. It looks like this one has more tunable components, which means a little more work to dial it in. I didn’t see any photos of the completed product.

19. Nick G0CWA built an interesting switchable upconverter design, complete with instructions and board layout PDFs.

20. Japanese amateur JA2GQP build a rather minimalist upconverter with only a 19 components offering a +50MHz frequency shift. He’s included a schematic and PCB mask for you to build your own very easily!

21. Cycle 24 Kits has a Multiband Converter available which uses a very small assortment of components and five switchable band-pass filters for 40/20/17/15/13 or 80/49/40/20/15/10 meters. Looks like a simple, no-frills kit that should be very easy to assemble!

cycle24kits converter

22. German amateur radio club Ortsverband Husum M04 has an SDR-Konverter with a very nice looking enclosure designed around the familiar NE602 mixer. The page is in German, but it looks like a quality product!


23. From the comments, I’ve learned about the SV1AFN Design Lab’s DC-55MHz upconverter for an RTL-SDR receiver. It features selectable bypass, selectable LNA featuring about 20 dB of gain from parallel Mini-Circuits Gali-74+ amplifiers, and a design with excellent filtration on the input and local oscillators to reduce harmonics and interference, it should be a very good performing upconverter-amplifier. It’s a kit with SMD parts pre-soldered; you wind a few transformers and connectors or you can purchase it assembled.


With these choices, there are plenty of options for getting HF signals into the VHF ranges for use with the RTLSDR. It’s not difficult to modify these plans for even higher fidelity and accuracy, such as by increasing filtering on the power lines, building a shielded enclosure, improved antenna systems, and more.

I’ve been using my v3.1 Converter from Wimo for a few months, and have been very happy with its performance so far – there’s little noise and leakage, and I use it to pull in shortwave broadcasts from all over the world including the BBC, China, Cuba, Japan, Russia and more from my home in Seattle with only an 80″ long wire and a string of adapters – I highly recommend that model, or any of the models in this family, for great performance. I’m looking forward to trying out some of these other ones.

If you have a design you’d like to see featured here, let me know!

Edit 12/1/2013: Added JA2GQP’s minimalist SDR upconverter.

Edit 10/29/2012: NooElec offers “Ham It Up v1.0″ upconverter which looks to be based on a different design, and seems very high quality. Check it out! 

Edit 2/2/2013: Better info about the Opendous Upconverter, KB1LQC’s DIY Upconverter, and WA7JHZ’s upconverter.

Edit 2/3/2013:Added 9A4QV HF Upconverter SDR UP-100, G0CWA 2012 upconverter, YO2LDK upconverter.

Edit 2/13/2013: Added Vandijken Elektronica upconverter and W9RAN RANVerter 2.0.

Edit 2/19/2013: Added KN0CK SMD HF Upconverter

Edit 2/25/2013: Added Matt GW0VNR’s Upconverter and the DGK Electronics HF Converter.

Edit 4/13/2013: Added JaniLab converters, High Sierra Microwave converter.

Edit 4/25/2013: Informed 9A4QV Out of Stock – Thanks Adam!

Edit 5/14/2013: Ham It Up v1.0 > v1.2, Now Ships with 125MHz Crystal

Edit 8/13/2013: CT1FFU v5 replaces CT1FFU v3.1, and some copy-editing!

Edit 9/2/2013: Updated to reflect availability of some items.

Edit 10/21/2013: Added Soft66RTL

Edit 1/28/2014: Added KN0CK Rev 5; more updates coming soon!

Edit 2/22/2014: Added Cycle 24 Kits and DARC-Husum SDR-Upkonverter and SV1AFN

Shortwave Radio Reception with the RTL-SDR Dongle

August 6, 2012 2 comments

I bought and did a quick setup on my RTLSDR dongle using SDR# a few weeks ago, where I used it to listen to FM radio stations around my area and a few public safety frequencies. That’s all well and good, but I’m much more interested in shortwave listening – when the weather is good, I can pick up a fair number of stations on my Hallicrafters receiver and there’s even more out there that I can’t tune in with that old equipment.

The RTLSDR tunes from around 64MHz up through around 1800MHz, but shortwave frequencies are much lower – only up to around 30MHz. Using an RF mixer, it’s possible to shift the signal into the RTL’s tuning range. Portuguese designer CT1FFU developed a mixing upconverter which adds 106.25MHz to the incoming signals, shifting them up into the correct receiving range and filtering out signals about 50MHz to prevent interference. His version comes as a kit which requires surface-mount soldering, but German retailer Wimo offers mostly-assembled versions of the kit which only need the antenna terminals and power connector soldered.

Finding those adapters was a bit challenging – I have a helical antenna which terminates in that alligator clip, feeding into a coax break-out, with an SMA-Coax converter. On the other end is an SMA gender-changer and an SMA to MCX adapter. Ultimately I ordered them from eBay and they work as intended. The USB port provides the +5V power supply for the converter’s operation but otherwise isn’t connected.

Reception is acceptable. With the aid of the SDR software, I can see where signals are more readily, but issues with my antenna setup and local interference are keeping it from performing as well as the Hallicrafters. I can identify human voices on more stations, but it seems there are fewer I can actually listen to with this equipment. I’ll probably try building a tuned loop antenna similar to this one, and see what I can do with better noise rejection and directionality. I might also add a low noise amplifier after whichever better antenna I end up using.

If anyone has a favorite, easy-to-build loop antenna for 10-160M I’d love to hear about it.


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