Suggestions for the new Ensemble RX receiver
- Tony Parks and I have recently discussed possible features for an update of the Softrocks Ensemble RX receiver. I recently reviewed a prototype of the receiver and published my test results on this board. I made some suggestions in that post and after a number of conversations with Tony he has asked me to publish a summary of the recommendations that I have recommended and that he is considering. Your input would be welcomed by both of us and could well determine if Tony moves ahead with a new model and what features it would have.
The most significant difference between the currently available RXII HF and the prototype I tested was the addition of a preamp for Band 3. This raised the performance of the high bands, especially 10 meters into parity with the elite commercial receivers currently available.
My recommendation to Tony was that he find a way to make the 15 dB attenuators that are inline with Band 0 and Band 1, and the 9 dB preamp inline with Band 3, user selectable.
Tony has found a way to add an additional FST 3253 to the board to provide switching paths for the -15, 0, and +9 dB system gain selections. Since the FST allows four discrete selections, I have suggested he add a fourth possibility that would allow a high attenuation path, up to 60 dB, to be selected when the receiver is used for local transmitter monitoring and tests such as IMD for transmitters.
This all looks eminently possible. The problem is how to control it.
Here, I am suggesting that he add another 3.5 mm jack to the board to allow external control of the four gain paths. An array of 2 SPST switches, connected to a stereo cable, and plugged into this jack would allow a binary selection of each of these four gain settings, independent of the Band setting. As an alternative to a switch array, the user could have three pre-wired 3.5 mm stereo plugs, the fourth possibility would be no plug, could be used to select the four conditions.
Tony has suggested, and I concur, that the additional jack be rear facing in order not to minimize the inconvenience to existing enclosures.
Finally, Tony would provide onboard jumpers that would disable the external control and default it to the standard of the new receiver: 15 dB attenuation on Band 0 and Band 1, clean on Band 2, and 9 dB gain on Band 3. Users who do not need or want the additional flexibility and complication could operate the receiver exactly as they do today.
Tony has indicated he would very much appreciate general reaction to these suggestions and asked me to post them on this board for comment.
Thanks for listening and for contributing to this project.
- Original Message -----
Subject: Re: [softrock40] Suggestions for the new Ensemble RX receiver
> I was not suggesting using IQ in this direct sound card approach. I think there would be no need. IQ is used normally to
> distinguish between two products of the mixer. No mixer, no products. HDSDR has input provision to only display one channel.
> I think a preamp of appropriate gain, perhaps one side of the op amp currently used in the Softrocks, would be all that is
> required to complete a VVLF receiver. All tuning and detection would be handled directly by the software.
> No big inductors!!!
I have tried this, the last time I was aware of the 18KHz SAQ transmission before it actually happened:) A good catch in
It did need a LPF but I got fair results without a preamp. I'm not sure if one would make it better. I think that with a long wire
sensitivity seemed adequate.
As you say HDSDR will work on mono inputs, I have the feeling I used SpecLab, that has a SAQ.usr.
73 Alan G4ZFQ