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Hi everybody,

I just repaired my Softrock Ensemble II and made tests on sensitivity across bands. It is like new! I noticed one nice thing. Indeed it can be tuned beyond 30Mhz. It has similar sensitivity, albeit a bit less, on 32Mhz and even beyond that. It is interesting to who wants to use the receiver as an IF in ancient V-U receivers, providing them a new life, or simply for the sake of tinkering.Does anybody know the upper limit that can be reached maybe replacing the bandpass filter number 3 with a high-pass filter?
73,?

Franco iz2oos

Does anybody know the upper limit that can be reached maybe replacing the bandpass filter number 3 with a high-pass filter?

Franco,

The Si570 is rated up to 160MHz. It will possibly go a little higher so /4 about 40MHz, maybe even 50MHz.
Sensitivity will be relatively low, in quiet locations a preamp is required even on 10m.

73 Alan G4ZFQ

Hi Franco,

Great that you found the problem and fixed it! Yes, it is nice to be able to fix and modify these boards.

As Alan says, it is a question of how high the oscillator will go, which you can discover by increasing the requested LO frequency until it stops going higher. Mine quits at about 40 MHz. Unless you are in an isolated location, changing the BPF to a HPF will lead to spurious signals from higher frequency signals like taxi, police, airplanes, especially around 3X the desired frequency as the detector has a 3X response mode. On the other hand, you could probably use the 3X mode by replacing the bandpass filter with one at 3X the frequency, up to the limit of about 120 MHz. The sensitivity is significantly lower in the 3X mode however so a preamp would be needed for anything except strong signals.

73,
Roger