«

»

Dec 05

The MiscDotGeek uBITX FAQ

The uBITX FAQ

The uBITX isn’t out yet, but already folks have a lot of questions about the kit. It’s my intention to answer as many of them as possible. Note: Questions about building the uBITX, what skills are needed, and suitability for beginners are all answered in the BITX40 FAQ.

How much does the uBITX cost, and where can I order one?

Pretty Maids All In A Row at the uBITX factory

Photo Credit: Ashhar Farhan

The uBITX went on sale on 12/9/2017 for $109. After the holidays it’ll be $129.You can purchase the uBITX at the official site, http://hfsignals.com.

Farhan’s goal has been to make high quality equipment available at a low price, as evidenced by the BITX40 only costing $59. The uBITX is equally affordable, while costing more than the BITX40 due to its higher parts count and more extensive labor required to build and tune the board.

How is the uBITX different from the BITX40?

The uBITX has a lot in common with the BITX40. It is the next step in the evolution of the BITX40 design and has some significant technological differences, and many added features. Let’s look at a few of the differences between the BITX40 and the uBITX:

Multi-Band

First and foremost, the uBITX is a multi band radio, and needs no modification to be active on all HF bands except 160m. That means you can use the uBITX on 80m, 60m, 40m, 30m, 20m, 17m, 15m, 12m, and 10m!

CW

Another wonderful feature is that the radio has not just SSB, but also CW! One needs only to connect a keyer.

Raduino Differences

The Raduino is used but with a different program and slightly different hardware. The SIS5351 DDS chip has three outputs. The BITX40 uses only one output for the VFO. The uBITX makes use of all three. Instead of providing only the VFO it also provides the BFO. The Raduino is also responsible for providing the CW tone when the CW keyer is used.

The Raduino plugs directly into the uBITX board, rather than with wires to the main board such as in the BITX40. The uBITX and the Raduino can be separated, as long as coax cable is used to connect the signal wires to the main board.

Power Amplifier and Output

The inexpensive IRF510 is still used. Instead of a single IRF510, there are two of them configured in a “push-pull” configuration. This is done in order to produce a cleaner output, eliminating the need for a Low Pass Filter on every band. This is why you see 4 sets of filters, but 9 bands are supported. As a result there are two heat sinks.

The PA produces 10W on lower bands, but the output decreases on higher bands. The lowest output is 5W on 28mhz (10m).

How big is the uBITX?

The board itself is 6″x5.5″, with the heat sinks for the dual IRF510’s extending past the rear of the board. The Raduino protrudes half an inch from the front of the main board.

Further uBITX reading and more information

I’ve skimmed over the current information available, but there is a multitude of information in the technical discussions and circuit descriptions in the links below.

Farhan’s uBITX page: http://www.phonestack.com/farhan/ubitx/ubitx.html

uBITX project announcement on the BITX20 group 3/2/17:
https://groups.io/g/BITX20/topic/ubitx_a_reboot_of_the_old/4438163

Problems with filtering 4/7/17:
https://groups.io/g/BITX20/topic/ubitx_stop_press/4809555

Teaser about uBITX availability 12/4/17:
https://groups.io/g/BITX20/topic/elves_are_at_it/7333141

6 comments

Skip to comment form

  1. Brian Ard

    Can i get one built ? as i cannot build it ..
    Regards , Brian K4ARD

    1. Ryan Flowers

      The board itself is built, one has to put it in an enclosure of any sort, and do some basic soldering. Check the BITX40 FAQ (linked toward the beginning of this one) for details.

  2. Brian Ard

    opps K4ARD is my call sorry

  3. K1RCE

    As always Sir, an excellent article. Thank you for the included links. 73, K1RCE

  4. Arthur Bryant

    Do you think that a QRP Labs VFO would work on a uBITX?

    1. Ryan Flowers

      Hi Arthur, No I don’t think it would be a good fit. It could be made to work, I’m certain, but I don’t think it would keep the radio fully featured as designed. The uBITX Raduino is very specific to the uBITX, but the QRP Labs VFO is just a VFO, with no BFO or CW tone output.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>