Tagged: upconverter

An Opensource Mini-Whip Antenna and Upconverter Design for RTL-SDRs

Thank you to Igor Yatsevich for submitting news about an open source Mini-Whip and Upconverter design that he's created and released for free on GitHub. An upconverter converts HF frequencies into VHF frequencies so that they can be received by RTL-SDRs in their quadrature mode, and a Mini-Whip is a small active antenna for receiving HF signals.

The designs include the PCB Gerber files for manufacturing, the components list and assembly and usage guides. Also both through-hole and SMD designs are provided.

The Mini-Whip design has a frequency range of 10 kHz - 30 MHz and to power it you'll need a 5 - 13V bias tee. You will need to install it up high and preferably away from the house as Mini-Whips are quite susceptible to local noise pickup. Another very important point is that Mini-Whips need to have a good ground connection. The upconverter is based on the ADE-1 mixer, and uses a 125 MHz local oscillator.

Igor's documentation on the project is excellent, and is a good read for getting more information about upconverters and Mini-Whips. He has noted that he is sending us some samples of units that he's built, so when we receive them we'll post again with test results. It looks as if he's put a lot of research into these designs so we're looking forward to seeing how well they work. 

Diagram on how to ground a miniwhip connected to a metal mast.
Diagram from Igor's documentation about how to properly ground a Mini-Whip connected to a metal mast.

Another GUI for Outernet’s Wideband Signal Generator moRFeus

Thanks to Ohan Smit for submitting news of his newly released GUI for Outernet's moRFeus wideband signal generator. Ohan's GUI works in both Linux and Windows. The Windows release can be downloaded from the GitHub Releases page. With the GUI you can change the mode between Mixer/Generator, generate noise, run a sweep, turn the bias tee on/off and generate a CW message.

A few days ago we also posted about about a moRFeus GUI by "Lama Bleu" which has similar functions. Although it only appears to run in Linux, Lama Bleu's GUI can interface directly with GQRX.

moRFeus is still currently on sale at CrowdSupply for $149 for the next 19 hours from the time of this post. The price is expected to rise after.

moRFeus GUI Generating a Sweep
moRFeus GUI Generating a Sweep

New GUI and Info on Outernet’s moRFeus Wideband Signal Generator

Back in March we posted about the release of Outernet's moRFeus device which is a low cost wideband RF signal generator. Since then we've received a few emails from two readers who've received their units and have found some interesting hacks and have developed software for it.

First we have a submission from Ohan Smit who discovered a hack that allows moRFeus to work as a wideband noise generator by setting the LO to 5 GHz and the Mixer current to 3. Together with an Airspy and the Spectrum Spy software he was able to measure the response of a bandstop FM filter. Over on the forums he also shows screenshots of Python based control software that he's developed for controlling moRFeus.

moRFeus Generating Noise
moRFeus Generating Noise

Next we have a moRFeus Linux GUI created by "Lama Bleu". It can be used to access the same functions as via the moRFeus LCD screen, but is also has a few very useful features such as a step generator which allows a generated tone to sweep across the frequency spectrum. The moRFeus GUI can also connect to GQRX and sync with the LO frequency specified in the GQRX GUI for easy control. It should also be possible to implement a CW morse code generator with some scripts.

Outernet moRFeus GUI
Outernet moRFeus GUI

Over on the forums Zoltan, one of moRFeus' designers also notes that it might even be possible to use moRFeus for WSPR modulation, although this isn't confirmed yet. It seems that moRFeus is shaping up to be a very useful tool for RF testing and experimentation.  The device is currently still available on Crowd Supply for $149US with over 136 units sold so far.

moRFeus: A Low Cost Wideband Signal Generator and Frequency Mixer

During development of the Outernet project the engineering team developed several tools to help them in their RF testing. One tool that they created has now been developed further into a commercial product that they are calling 'moRFeus'. moRFeus is a small handheld RF signal generator and frequency mixer. It can be used to generate an RF tone at any frequency between 85 MHz - 6 GHz and to upconvert or downconvert signals via the mixer with an input/output frequency range between 30 MHz - 6 GHz. This type of tool is useful for people working with RF hardware as it can be used for testing and prototyping.

morRFeus is currently selling for US$149 over on CrowdSupply, and the units are ready to ship out soon. They note that the current price is a special, and that it may be increased in the future. We think that this is a fairly good deal considering that similar products can cost much more. If you are interested in the technical details the datasheet includes figures on phase noise and conversion losses. There is also a user guide that explains how the buttons work, and what each screen on the menu is for.  The morRFeus press release reads:

Outernet launches sales for wideband frequency converter and signal generator with complete field-level configuration.

Today, Outernet announced the launch of moRFeus - a wideband (30MHz - 6GHz) frequency converter and signal generator with complete field-level configurability. The product is available on Crowd Supply for $149. The price will increase after the 30-day launch campaign.

The device has an LCD display and button interface for complete field-level configuration - from setting the LO frequency to toggling between mixer and generator mode, and more. It’s in a precision-milled all-aluminum enclosure for durability and aesthetics.

moRFeus was built for hams and hackers, people with a traditional amateur radio background, as well as a makers and researchers that are interested in RF experimentation. It was designed for easy integration into a wide variety of RF projects.

In mixer mode, moRFeus enables dynamic frequency up- and down-conversion. In generator mode, it is one of the most, if not the most, affordable tools to generate a stable +/-2.5 ppm CW signal. Additional information on features, specifications, and performance metrics can be found in the datasheet.

The team already has 100 units in stock and another 900 are going through final assembly and quality assurance in Chicago. The first 100 units will ship one week after launch and orders beyond the initial stock will ship within 30 days of the close of the campaign, or earlier.

Outernet has been working on novel RF projects since the founding of the company in 2014. moRFeus was developed because from an internal need for a wideband field-configurable frequency converter for testing purposes. The company identified a huge gap in the market for a solution that met the needs of others with similar problems add their own. Outernet’s founder describes the development process:

“The idea was hatched about a year ago because we needed an easy, quick way to dynamically up-and down-convert the various radios we were experimenting with for a new product. By the summer of 2017, we had our first prototype and functional firmware. The design still required some slight tweaking. The current version of moRFeus is its third iteration. Oddly enough, the last phase of the project, industrial design, ended up being the most time-consuming. We worked with a local designer/machinist with decades of experience to come up with a custom-made all-aluminum enclosure.”

For more information and to purchase moRFeus, visit Crowd Supply.

Furthermore the product features, description, and also some of the applications and use cases for moRFeus are quoted below:

Features

  • RF Input Frequency: 30MHz–6GHz
  • RF Output Frequency: 30MHz–6GHz
  • LO Frequency: 85MHz–5400MHz
  • Fractional-N Synthesizer
  • LO Step Size: 1.5–3Hz1
  • 2.5 ppm precision TCXO
  • USB programmable
  • Generator/Mixer Function Toggle
  • Input IP3 +23dBm
  • Small, Portable Form Factor
  • Adjustable Mixer Bias Current
  • LCD Display With Backlight Feature
  • Button Control Interface
  • Dimensions: 88mm x 38mm x 68mm
  • Weight: 7.4 oz

Product Description

moRFeus is a 30MHz–6GHz programmable Fractional-N wideband frequency converter and generator designed for low spurious emissions and dynamic configuring of the LO frequency. moRFeus is designed for easy integration into popular RF environments using SMA connectors and is powered using an external micro-USB 5V supply. The LCD display and button interface provide a dynamic way to program the mixer LO frequency in the field with a step size of 1.5–3Hz.1 The device is USB programmable, enabling automatic operation from a PC (must be running Linux). Dynamic toggling between mixer and generator modes adds to field-level functionality. An optional bias voltage of 5V is available via RF choke to the mixer input to supply active antenna systems.

Applications

  • Wideband Radios
  • Distributed Antenna Systems
  • Diversity Receivers
  • Software Defined Radios
  • Frequency Band Shifters
  • Point-to-Point Radios
  • WiMax/LTE Infrastructure
  • Satellite Communications
  • Wideband Jammers
  • Remote Radio Heads
  • Frequency Up/Down Conversion
  • Automated Test Equipment (ATE)
  • Wireless Communication Systems
moRFeus Block Diagram
moRFeus Block Diagram

Review and Testing

The Outernet team sent us a moRFeus unit for testing a few days ago. It comes in a portable 3.5 x 2.7 x 1.5 inch (8.9 x 6.9 x 3.8 cm) conductive milled aluminum enclosure and weighs 7.4 ounces (210 grams). The construction is very solid, and should easily survive being thrown around in a carry bag, although we'd still advise caution as the LCD screen is not protected by a window.

The unit is powered via a standard micro USB port. After connecting a USB cable the unit immediately powers up shows a frequency selection screen on the LCD display. Five small buttons are used to control the interface, and we found it very easy to adjust the output frequency using these buttons.

Using the interface the unit can be switched between the "Generator" and "Mixer" modes. In the generator mode moRFeus simply generates a CW tone at the desired frequency. In the mixer mode moRFeus takes an input signal, mixes it with the generated tone and puts the result on the out port. Mixing a signal with a tone is the core concept behind devices like upconverters, downconverters and tuners. For example, by generating a mixing tone at 2 GHz with the moRFeus, we are able to view 2.4 GHz WiFi signals at 2.4 GHz - 2 GHz = 400 MHz.

In the screenshot below we set moRFeus to run in mixer mode with the LO frequency set at 2 GHz. This allows us to view an active WiFi signal at 2.475 GHz using an Airspy and the SpectrumSpy software. The Airspy can only tune up to 1.8 GHz by itself, so it can't view the WiFi band directly. Of course to use as a proper downconverter filtering is required to remove any images and interfering signals, but by being able to easily change the LO frequency you are able to move the signals around quite easily to avoid images or interference.

Unfortunately one limitation is that moRFeus' lowest input frequency is 30 MHz, so it can't be used to upconvert HF signals.

Viewing a 2.4 GHz WiFi signal on an Airspy by using moRFeus as a downconverter.
Viewing a 2.4 GHz WiFi signal on an Airspy by using moRFeus as a downconverter with LO set to 2 GHz.

moRFeus also works well as a standard RF signal generator, and we were able to get a clean CW tone on any frequency between 85 MHz - 6 GHz.

moRFeus as a RF signal generator
moRFeus as a RF signal generator

moRFeus also shows up a a device on the PC, and the team write that it is possible to control it programatically via Linux, however documentation for this does not exist yet although it is scheduled to be released later. We would love to see a sweep feature which should be possible with PC control.

In conclusion if you are looking for a low cost signal generator or mixer to use in your experimental RF projects, then moRFeus certainly does seem like a good deal. A tool like this is very handy to have in your RF kit.

Adam Tests his UP-64 Upconverter with an RTL-SDR

Over on YouTube Adam 9A4QV has uploaded a video of him testing out his 'UP-64' upconverter together with an RTL-SDR. An upconverter moves low frequencies 'up' into a higher frequency. This is useful for HF reception, as normal reception on an RTL-SDR starts at about 24 MHz (without using direct sampling mode).

Adam previously manufactured and sold his UP-100 upconverter, which was an upconverter of his own design that utilized a 100 MHz oscillator. These days it has been accepted that using an upconversion frequency that avoids the broadcast FM band is generally better as it avoids the interference that can come from very strong FM signals. The 64 MHz oscillator on the UP-64 avoids the broadcast FM band for the most part unlike the older UP-100.

RTL-SDR + UP-64 test on 14MHz

Modded SUP-2400 Downconverters now Available at RXTXDX.com for $25

Last week we posted about KD0CQ’s interest check on his ready to go modded SUP-2400 downconverter. Interest was strong so the unit is now available for sale on a store he’s just set up at RXTXDX.com. The ready to go unit costs $25 USD including a 9V battery plug and F->SMA or MCX adapter.

Last year KD0CQ discovered that the SUP-2400 is a cheap $5 – $10 DirecTV (US satellite TV) module which can be hand modded into a downconverter for the RTL-SDR. A downconverter allows you to listen to frequencies above the maximum frequency range of the RTL-SDR by converting frequencies down into a range receivable by the RTL-SDR (or of course any other SDR). The modified SUP-2400 allows to you listen up to just over 4 GHz.

The SUP-2400 modification is moderately involved and requires soldering and desoldering SMD pieces, so this product is great for anyone who just wants a cheap and low cost downconverter which is ready to go. And at $25 USD it’s still very good value. Shipping within the USA is $7.75, and internationally it is about $13.50.

The modified SUP-2400 Downconverter
The modified SUP-2400 Downconverter

A Homebrew One Transistor Upconverter for the RTL-SDR

Recently Qrp Gaijin wrote in to us and wanted to share his experiences on building a one transistor diode-ring mixer upconverter for his RTL-SDR. An upconverter for the RTL-SDR translates low HF frequencies ‘up’ into ones that are receivable by the RTL-SDR. This is a different method to the direct sampling mode used in the V3 dongles to achieve HF reception.

Qrp Gaijin’s post goes into some detail about his circuit and shows the schematic as well. He also shows the results with an active loop antenna, RTL-SDR and the upconverter in some videos. In the email to us he also notes that his upconverter is still a work in progress as the LO is quite noisy and he suspects that it may be too weak to drive the 1N4148 based diode ring mixer. There is also no filtering on the circuit yet, so there is some broadcast FM breakthrough.

Another project he worked on was attempting the direct sampling mod on a standard RTL-SDR. However, Qrp Gaijin’s method is slightly different to most attempts as instead of soldering the wires into the Q-branch holes he simply uses hot glue to hold them mechanically in place. This may be an idea to consider for those who want to attempt the mod on a standard RTL-SDR, but don’t have any soldering tools or experience.

Homebrew RTL-SDR upconverter: physical construction

Potentially Receiving up to 10 GHz with an RTL-SDR and Multiple SUP-24000 Downconverters

Back in 2016 KD0CQ discovered that a $5 DirectTV device with model name SUP-2400 could be used as a downconverter with an RTL-SDR for receiving frequencies of up to 4.5 GHz. A downconverter is a device that converts high frequencies such as 4.5 GHz down into a frequency actually receivable by the RTL-SDR. The SUP-2400 is able to be modified into a useful downconverter by opening it up and manually removing some mixing harmonic filters.

In his latest post KD0CQ shows how you could combine four modified SUP-2400 downconverters to create a quarduple conversion mixer which allows you to receive up to 10 GHz. The post goes into the mixing math and practicalities of this idea. KD0CQ writes that some amplification will most likely be required to push the signal through, and in the past he’s managed to receive up to 7.5 GHz.

The SUP-2400 Directv upconverter that can be converted into a downconverter.
The SUP-2400 DirecTV device that can be converted into a downconverter.