Monday, August 10, 2020

Dragonfly RX-666: Some Points to Consider

Having spent quite a few hours with the RX-666 over the weekend, I feel confident enough to come up with an evaluation of the receiver and its interaction with software. The link is here.

Saturday, August 08, 2020

Dragonfly RX-666 - A New Player?

(Updated AUG-9 2020)

I have been playing with the new, China-manufactured RX-666 for quite a few hours the past couple of days. There has been quite a bit of interest in this device, especially since it claims to sample a whopping 32 MHz of bandwidth. I will do a write-up soon, but since questions are plentiful, I will outline some points of interest below.

1. The RX-666 is the brainchild of IK1XPV Oskar Steila and his project BBRF103. There is no controversy on this. The Chinese manufacturers (whoever they are) used his open-source project, which is completely legal. What surprises me (and him) is that they never let him know about it. 

2. It uses an LTC2208 ADC from Analog Devices. This is a 16-bit ADC. Some say it is the same that sits in the Excalibur G31/G33 etc. series. I can't confirm that. Oskar's original design used the LTC2217 ADC.

3. For VHF/UHF use, it uses the R820T2 tuner chip. It has capacity for 8, possibly 10 MHz, for instance for use on the FM band. The modified HDSDR exes are needed for sampling 2, 4 or 8 MHz. On the official HDSDR version, it will only sample 2 MHz. VHF/UHF will always start fully attenuated, leaving you to assume that there is no coverage.

4. Current sampling rate options are 32, 16, 8, 4, and 2 MHz. Alias-free ranges (limited by firmware filters) are 28.8, 14.4, 7.2, 3.6 and 1.8 MHz. Minimum LO setting is 1000 kHz with 2 MHz sampling. This means that with the current dll, minimum tuneable frequency is 100 kHz. No VLF reception yet. 

5. There is no LNA in the circuit, so sensitivity is a bit low. A good-quality preamplifier resolves this.

6. On an i5-6500 PC with 8 GB RAM, full sampling requires 30-55 % CPU. Recording 32 MHz to an external hard drive is more challenging, resulting in stutter. Playback of a 32-MHz file in SDR Console is ok.

Sampling 32 MHz with original BBRF103 dll and official HDSDR software

7. Software is available from the manufacturer in some sort - a version of HDSDR which does not seem to be original, an ExtIO dll and assosiated files, and Cypress drivers. Driver must likely be installed manually (I had to). No problems though.

8. The RX-666 will run from an official HDSDR installation. And more: It will run with the dlls that Oskar developed for his BBRF103 project.  I strongly recommend any RX-666 owners to use the original HDSDR software and the original BBRF103 dll files.

9. Temperature control: None except the box which is warm but not hot. Internal air temperature is around 40 Celsius after 6-7 hours with full sampling. Ambient is 23 Celsius.

10. DO NOT USE THE OPTIONAL 5VDC CONNECTOR!   You don't need it either.