I have an ANAN-10 that I intend to use on 6m with an SSPA and with 144 and 432 transverters which will be used on the intended band and as drivers for microwave transverters.
There are lot of RX spurs on 28 and 50 MHz but that is the subject of a separate topic.
I will concentrate on in band TX spurs which are at an unacceptable level for my intended application. I suspect that the problem can be solved by better filtering of a yet to be determined SMPSU device.
For all these tests a clean linear supply was used. I investigated the problem as a result of communication with other ANAN-10 users one of which shared plots when running from a battery. Suffice to say that the problem is not from a external supply.
The single tone was generated using the TUNE control in PowerSDR mRX V3.4.9
Here is the first plot at a fairly wide RBW at 8W output.
I decided to investigate further at different power levels and so that I could see deeper I decreased the RBW of the spectrum analyser.
This plot is at 3W out
Now 1W output
Finally from the TX out with the PA disabled.
This is unacceptable for serious VHF use with high power and high gain antennas. Due to the low noise floor of other users at least 90dB suppression of all in band spurs is required. I am quite sure that this can be achieved and that this is just poor filtering of an SMPSU device or ground issues on the 3V3 domain. I would like Apache or the designers to investigate and maybe offer some suggestions as to what modifications may be helpful. I suppose that this is very low priority as it will not help new sales.
Anybody else who may have a suggestion feel free to contribute. I have had a pretty negative experience so far with Apache hardware. I would like to think that this has all been cured on Orion based models but who knows? Anyone with the relevant hardware please check this out.
73
Conrad PA5Y