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HF converter for SDR radios

Posted by Kalle Hyvönen Posted on Dec - 10 - 2012

I wanted to listen to HF bands using my RTLSDR USB dongle. Since the RTLSDR dongle can only receive from around 64MHz upwards I needed an up-converter which converts the HF band (0-50MHz) to a higher frequency I can receive with my dongle. The converter will work up to about 70MHz.

Many of the available converters seemed quite pricey and not too well designed (no filtering on the local oscillator etc.) so I decided to make my own.

The converter is fairly simple, it consists of an elliptic low-pass filter on the input, a local oscillator with a band-passfilter, a mixer and a Butterworth band-pass filter on the output. The converter takes in a signal in the 0-50MHz range and mixes it with the 100MHz local oscillator, yielding a 100-150MHz signal you can receive with an RTLSDR dongle.

After quite a bit of reading filter design books and simulating this is what I ended up with:

HF converter schematic

HF converter schematic

If you’re wondering why the signal is going in to the “IF out” pin of the mixer; it’s not a mistake. This is a small trick you can use to extend the frequency response lower when you are up-converting.

The mixer I used is an ADE-1 from Mini-circuits and the local oscillator is an ASEM series oscillator from Abracon (100MHz +-50ppm model).

I ordered the PCBs from iTead:

Finished HF converter

Finished HF converter

Few HF converters with an RTLSDR dongle connected to one

Few HF converters with an RTLSDR dongle connected to one

Here is a 0-50MHz (-30dBm) sweep on the input and spectrum analyzer connected to the output:

0-50MHz conversion sweep, input -30dBm

0-50MHz conversion sweep, input -30dBm

Here is a 10-150MHz sweep of the elliptic Cauer low-pass filter on the input:

50-150MHz sweep of the input Cauer low-pass filter

50-150MHz sweep of the input Cauer low-pass filter

This equates to around 9dB conversion loss (typical for a ring diode mixer) with around few dB ripple on the passband so I’m pretty happy with it! There is about -51dBm of LO leak on the output which is also quite low.

I did some testing by unwinding a few meters of wire from a roll and used that as an antenna and this worked really well. Lots of signals to listen to!

The converter is designed so that it should fit to one of these (just need to cut the box a bit shorter):

Box for the HF converter

Box for the HF converter

I have a few of the converters left if someone is interested in one! You can contact me at kalle.hyvonen ^AT^ dgkelectronics.com

edit: Added a picture of a 10-150MHz sweep on the input low-pass filter

Categories: Electronics projects, HF converter, SDR radio

44 Responses so far.

  1. Sri Bintoro says:
    24/04/2013 at 09:49

    Hello, i am from Indonesia.

    Do you have some for sale and what’s the price for it including post & package to Indonesia?

    Sri Bintoro

    Reply
  2. Txema Araluze EA2AFR says:
    23/04/2013 at 20:23

    Dr Kalle
    Please let me know if still not availability of your UP_converter. I’m waiting for some time because even there in the market are msome other units I like very much yours.
    So if there is the oportunity to get 3 units, please, let me know.

    Thank you very much in advance. Greetings from Basque Country.

    Txema – EA2AFR

    Reply
  3. Johanes Hermanto says:
    13/04/2013 at 00:07

    Hi,
    Do you still have the upconverters? Could you email me the detail how to get one, please? Thanks.

    Johanes

    Reply
  4. darethehair says:
    09/04/2013 at 16:33

    Info on your HF upconverter for Canada? Thanks!

    Reply
  5. Ricky Marsh says:
    22/03/2013 at 02:19

    I do still have the filters for sale, if so how much delivered to the UK.

    Thanks

    Ricky

    Reply
  6. Txema Araluze - EA2AFR says:
    16/03/2013 at 11:05

    Dr Kalle
    Looking around for some infos concerning to an up_converter for my RTLSDR dongle I found you.
    First of all I must say I’m a newcomer (or better said a perfect NULL on that) and I’m doing my vey first steps. searching for a not very expensive device I’ve found the info referred at your converters. Now the question is that:

    Still having this converters (at least one of them) ?.
    If that’s OK, please, let me know how much money is it and what to do for sending you the money (Bank account, PyPal, etc.).

    I thank you very much in advance and, please, excuse me but I can’t do better with my “Spanglish” HI HI.

    Greetings from Spain

    Reply
  7. Giannis Grammenos says:
    12/03/2013 at 10:26

    Hi,
    Do you have any of the kits available
    Can you give me price and shipping for Greece
    Thank you

    Reply
  8. Lothar says:
    08/03/2013 at 10:13

    >Hello,
    do you have still some for sale and whats the price for it including post & package to Germany?

    Regards 55/73

    Reply
  9. Dominic says:
    05/03/2013 at 16:04

    Do you still have any left?

    72

    Dom
    M1KTA

    Reply
  10. Pravin K says:
    28/02/2013 at 14:14

    Hi,
    Do you have any of the kits available for sale?
    Please send pricing if available.

    Reply
  11. Round-Up of RTLSDR Upconverter Choices | KF7LZE's Blog says:
    26/02/2013 at 05:46

    [...] Kalle over at DGK Electronics has a great looking compact 100MHz HF converter / upconverter designed to fit inside of a pre-made [...]

    Reply
  12. Jaime says:
    21/02/2013 at 16:31

    From Portugal and I’ interesed in one of this sdr converter,do you sell to portugal if so, how much ,include postal.

    Many thanks

    CT1ESU Jaime

    Reply
  13. Dana says:
    21/02/2013 at 02:26

    I’m interested in this converter if available?

    Reply
  14. Carlito says:
    16/02/2013 at 03:37

    I am interested too. Please give me details.

    Reply
  15. Andrea says:
    12/02/2013 at 00:59

    Hi,
    I’m interested in your hf converter. Can you give me price and shipping for Italy? Thank you.
    Bye.

    Reply
  16. CERA says:
    11/02/2013 at 13:30

    Hello,
    We have an idea of the price with shipping cost for France?

    Greetings

    Reply
    • CERA says:
      11/02/2013 at 14:46

      I’m finally interested for an order of one or two converters.
      I would like to know what manner I can pay you.
      Credit card, check, or other.
      For information I live in France in Paris.

      Reply
  17. Steve Smith says:
    08/02/2013 at 09:12

    I am interested in one of the converters as well, thanks and 73.

    Reply
  18. Gm0lze says:
    05/02/2013 at 09:21

    Are there any converters still available.Thank you.

    Reply
  19. Gm0lze says:
    05/02/2013 at 09:06

    Really nice design.Do you have any available ..

    GB3IG.

    Reply
  20. Jon says:
    03/02/2013 at 16:06

    Hi,
    If these are available to buy please can you email detail.
    Did you test the low end response?
    Many thanks
    Jon

    Reply
  21. Dave Richards AA7EE says:
    17/01/2013 at 22:35

    Kalle –

    I sent you an e-mail. Am interested in this HF converter. I especially like the fact that you used a diode ring mixer instead of the NE602 device that is used for the mixer in most of the other similar designs I have seen.

    Dave
    AA7EE
    Oakland, CA.
    USA

    Reply
  22. millot daniel says:
    04/01/2013 at 00:26

    Oh, i forgot to ask you how to order your hf converter for sdr
    Thank you
    Daniel F6FTC

    Reply
  23. millot daniel says:
    04/01/2013 at 00:17

    Happy new year from france
    I’m interested by your hf converter for sdr,can you please give me its price and shipping for france (burgundy)

    Reply
  24. andoras says:
    02/01/2013 at 18:52

    hello and happy new year from France ! what’s the price in euro of this hf converter please ?
    thank you.

    Reply
  25. David KB6QMX says:
    01/01/2013 at 09:38

    I am interested in a HF converter for my RTL2832 dongle. After reading the latest edition of QST I am interested in setting up SDR for the first time and trying it out. Will your converter do what the article says without me having to make the converter for the amateur bands? Will it cover 160-6 meters with a Newsky TV28T USB DVB–T & RTL-SDR Receiver? If it will work then I am interested in purchasing one from you. Happy New Year and thanks for your reply.

    Reply
    • Kalle Hyvönen says:
      01/01/2013 at 18:13

      Hey David! My converter should work just fine with any SDR-radio (or any radio for that matter). It will cover about 0.5-70MHz (most likely even lower than 0.5MHz, I will measure this soon) so it will work just fine on the the 6-160 meters range.

      Reply
  26. Luis Felipe says:
    30/12/2012 at 21:52

    Hi, I’m interested in one of your Hf converters, I wonder if you still have, and what is your price to send it to Spain.
    Season Greetings and thanks in advance.
    Luis.

    Reply
  27. Lyndel, N7LT says:
    26/12/2012 at 06:08

    Hello, I’m also interested in one of your smart looking converters, do you still have them?

    Tnx es 73
    Lyndel, N7LT

    Reply
  28. David Gilpin says:
    25/12/2012 at 06:57

    Please advise how may order and how much. Very interested. Thanks. David

    Reply
  29. Benjamin says:
    24/12/2012 at 01:47

    Hi,

    Do you have any of these left? Shipping to the UK.

    Happy New Year!

    Reply
  30. Gerry Jannetta says:
    14/12/2012 at 14:37

    Hi, I am interested in one of your Hf converters.
    How much to purchase one please.

    Regards Gerry (G4 NYC)

    Reply

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