Ensemble II RX

I was eager to try out WSPR hopping on all bands, not only the 7, 10, and 14MHz bands that my Softrock Ensemble RXTX covers, so I ordered a Ensemble II RX kit from Tony Parks. The kit arrived a couple of days later in two envelopes.

Building the kit took a few hours. I didn’t count, but it was probably 8 or 10. The build went relatively smoothly. I used Robby’s fantastic instructions to sequence the build and to help in identifying parts. The main snag during the build was that the Si570 synthesizer did not produce the frequencies that it was told to produce. (I discovered this with an oscilloscope, which is really useful for this kind of debugging.) The USB connection worked fine, so the microcontroller received the tuning commands from the laptop, but for some reason the Si570 did not actually tune. A visual inspection of the soldering suggested that pad 7 (SDA), the one on the right in the picture, is not soldered properly. Pads 7 and 8 are really tiny and are difficult to solder; the other 6 are larger so they are relatively easy to solder. I did my best to fix the soldering and the synthesizer started working.

Since the soldering problem was at the one of the I2C pins of the synthesizer, I assume that the microcontroller was not able to communicate with it at all. Unfortunately, it appears that the microcontroller does not inform the USB host that communication with the synthesizer fails, so on the PC side you think that everything is fine.

Other than this I didn’t have any particular problems. A couple of solder bridges on the SOIC and SOT-23 packages, but they were all easy to spot and easy to remove with a solder wick. That was about it. I connected the receiver to an antenna and started using it. I need to put it in a box, but it’s already usable.

I left the receiver connected to the wideband active loop and to a laptop running a beta version of WSPR 3.0 for 24 hours, and hopping on all the 10 amateur HF bands. I received distant stations on 3.5, 7, 10, 14, 18, 21, and 28MHz.  On 5 and 24MHz there were very few transmitting stations and I didn’t spot any of them. On 1.8MHz there were quite a few transmitters, but either propagation was not good enough for me to receive them or the noise level was too high. But the range of frequencies that I did receive indicates that both the receiver and the antenna work reasonably well over all the HF bands.

3 Responses to Ensemble II RX

  1. Pingback: A Papier Mâché Electronic Enclosure « Eclectic Technical Experiences

  2. Hi Sivan

    Just came across your article. Thank you. Can I ask how you fixed the solder bridges under the Si570?

    Kind regards and 73s


    • Sivan Toledo says:


      If I remember correctly, the problem I had with the Si570 was not a solder bridge but a pad that was not connected at all. I think I just cleaned up the area as much as I could with a solder wick and then applied solder again.

      The bridges that I mentioned were on easier-to-deal-with packages, SOIC and SOT-23, and I remove these with a solder wick. These are kind of routine for me when I solder small packages.


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